I understand I may be posting about this subject too much, but each thing is a topic on its own that is very lengthy, to the point where it may justify its own topic.
I posted this on the peakoil.com forums a while back.
http://www.peakoil.com/fortopic9721.html
A few here at the pavilion have PMed me for info on how to build an electric car and where to look for parts many months ago. Just in case people have questions again, this topic will therefore be made. I want to provide the most useful info I can to the best of my ability. Without further ado, here it is.
***NOTE: This was written when gas was about $2/gallon. The comparison between electric and gas uses $2/gallon. At $3.50 today, the electric car offers even more savings.
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So, you want to build an electric car, or are at least interested in building an electric car? I apologize for the grossly long topic, but this post only touches the surface of this subject and is by no means in-depth, but I chose to include information that I felt would be relevent to someone new to the subject with minimal skills when it comes to working on cars.
This topic is divided into six sub topics:
I) How will you use your EV and what sort of EV will you choose to make.
II) How to go about researching the parts you need and how to build the car, and how to figure out what to expect of the car’s performance in range and acceleration.
III) Internet and literature on electric vehicles
IV) Where to buy parts
V) Specs and cost analysis of three conversion examples(Compact, sports car, and pickup)
VI) Maximizing vehicle efficiency
VII) Other areas of interest(electric car myths and politics, electric car racing)
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I) First thing is first, you need to ask yourself the following questions:
1) How much am I willing to spend? Expect to spend at least $5,000 for a basic highway capable conversion, probably $6-8k for a typical conversion, or higher at $10k on up or so if you want a go fast EV or a long range cruiser. Does not include cost of the chassis you choose to use. You might think that is expensive, but many of the parts you will use are hand-made. It’s all about production volume.
2) What kind of car do I want? Midsize, compact, pickup, sports car, wagon, SUV? What are my utility needs? Will I be satisfied with the car and want to keep it? Choose a car you like and a car that will suit your needs. A sports car may not have a lot of battery room, but a pickup will have a ****load of it. Likewise, that pickup may not be anywhere near as energy efficient as that sports car.
3) How much range do I need? How much range do I want? Lead acid is the only 'affordable' battery right now, due to reasons of politics on some chemistries and low production volume relative to automotive application on others. Lead acid can easily do 40-60 miles per charge for a typical run of the mill conversion, 100 or more in an efficient vehicle or a pickup truck loaded with almost half its weight in batteries. If you're willing to hand build a battery pack for $30,000 or more, you could do Lithium Ion and have 300 miles range, but since electric cars aren't produced along with automotive sized lithium batteries, you'll be on your own or excessively wealthy if you want a hand-built lithium battery pack from thousands of laptop batteries. With lead acid batteries, cold weather affects range. If it's freezing outside, your lead acid battery will only deliver about half the range you'd normally get, unless you have a heating system to keep it warm, which will then allow you full capacity.
4) How much work am I willing to do? A conversion will take anywhere from 100 hours work for a basic conversion to 500 hours or more to a dedicated race car or efficiency perfected long range cruiser. This doesn't count research.
5) WHY do you want the car? Here's a list of reasons why one might use an EV:
a) Want a means of transportation that doesn't support despotic regimes in the middle east
b) Want a cheap way to have a fast car
c) Want a car that doesn't cost much to run
d) Want to reduce environmental impact of a 1st world lifestyle
e) Want a means to get energy for a car from renewable fuels(Solar, wind, ect.)
f) Want a car that will last for life(Barring accidents, tornados, ect.)
g) Want a car that will always start in the morning, even on a cold winter day
h) Want to avoid rising gas prices
i) Want to boycott auto monopolies
j) Want to embarrass V8s with torque out of this world
k) If your power goes out you can keep your lights, TV, refrigerator, ect. going with your car.
l) It offers a means to power your transportation with wind or solar energy.
This list is by no means all-inclusive. Some reasons work well for some, other reasons for others. What do you want out of the car? Why would you want to drive an electric car?
6) What ancillaries do you want? Heating, air conditioning, high output stereo system? All these things add cost. You can choose to run them off a 12v battery and have to recharge that individual battery with your battery pack, or choose to use a DC to DC converter so that you don’t have to worry about an extra battery.
7) What kind of maintenance are you willing to do? Electric cars need virtually none, but flooded batteries will need to be watered about every 2,000 miles with distilled water and cleaned as often to prevent corrosion, while sealed lead acid batteries will not. Are you willing to water a set of batteries to save even more money, or would you rather have a hands off approach? Use tap water on flooded batteries and the metals in the tap water will ruin them.
8) What are your performance goals? Flooded lead acid batteries don't have the power to let you go fast, while sealed lead acid batteries do. Sealed lead acid batteries are more expensive than floodeds.
Other options if you don’t want to covert a car is to buy a used conversion. However, labor went into that conversion which you will have to usually pay for and used conversions are usually built on old chassis so you will likely not find such an endeavor worth it.
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II) Second, is research. You'll be doing a lot of that before you begin building.
1) Find the chassis types that will fit your needs. Parameters you need to look for:
a) Dry weight- How much the car weighs with all fluids, spare tires, and people removed. This will affect your rolling resistance. Lower weight means lower rolling resistance and thus more efficiency and greater range per pound of battery.
b) Drag Coefficient- How much resistance your car's shape poses to outside air. Lower coefficient of drag means less drag force is induced on the vehicle at speed, meaning greater efficiency and more range.
c) Frontal Area- Cross sectional area of the vehicle. Smaller is better. To estimate it, take width times height times .8. Smaller frontal area means less drag and thus more range per pound of battery.
d) Cost- How much does the chassis cost?
e) Condition- What shape is the chassis in? How much will it cost to repair it to a point where you will be happy with it?
f) Reliability- Does the car have reliable brakes, wipers, ect., and if it doesn't would you be happy with it as is or willing to fix it to be more reliable?
g) Battery room- How much overall space do you have to place batteries?
h) Rarity/commonality- Will you even be able to find the car, or parts for it should something break?
i) Gear ratios and transmission- This will affect how fast you will be able to go. Will the ratio allow me to have the top speed I want with the max motor RPM of the electric motor I wish to use? Can the transmission handle the torque I will deal to it with the motor and controller combination, or will I need to bolt in a transmission that is stronger?
j) Gross Vehicle Weight Rating(GVWR)- This is the weight your vehicle can withstand before it becomes unsafe because of elongated braking distances and changed handling characteristics. You'll need a high GVWR in contrast to dry weight because you'll be stuffing in a lot of battery weight. You can exceed GVWR, and install leaf springs to keep your suspension from sagging, but you won't want to go more than 200 pounds over, including weight of driver and passengers.
2) Batteries. Flooded lead acid or sealed lead acid? Lithium ion or nickel cadmium instead? This will be based on your needs for range, performance, and cost. Flooded lead acid batteries provide better low speed range per pound than sealed lead acid batteries, and sealed more high speed range per pound than flooded. As a general rule, if you're going to use all your car's range in less than an hour, sealed will give you better range per pound, and if you'll use all the range in more than an hour flooded will give you more range per pound. Flooded lead acid batteries are poor on power and will not allow you to accelerate like a normal car. Sealed have more power than you'll ever need and can allow you to out accelerate Ferraris with the right motor and controller combination. Want to perform like normal and not either of the extremes? You'll want sealed. Just want to go highway speeds and don't care about speed? Flooded would suit you fine. Per mile, sealed lead acid batteries are the most expensive battery, flooded lead acid are the cheapest lead acid, and other batteries true costs aren't realized because they are not produced in the volume of lead acid, but often exotic chemistries like nickel cadmium are more expensive up front but cheaper per mile because of their long lifespan. Lead acid batteries further suffer from Peukert's effect, which means that they won't get their 20 hour rated capacity out of them at higher rates than taking 20 hours to discharge the battery.
The equation for Peukert's effect is as follows:
(I^n)*T = C
C is a constant called Peukert's capacity. It is akin to the total number of amp hours a battery can deliver at a current draw of 1 ampere. However, the unit itself is not expressed in amp hours due to the exponent.
I is the average current draw of the battery in amperes.
n is Peukert's exponent, how much the effect applies to the lead acid battery in question. Sealed generally have an exponent around 1.05 to 1.15. Flooded are generally around 1.2 to 1.4.
T is the time in hours the battery will deliver the current I.
Batteries don't come with Peukert's exponent and Peukert's capacity labelled on them. You have to solve them. Batteries are rated at the 20 hour rate in amp hours and at the 25 amp rate in reserve capacity, reserve capacity being the total number of minute the battery can deliver 25 amps. Using logarithms allows one to solve for the Peukert's numbers.
For power, you want low internal resistance. Power in kW = volts * amps
Your voltage drop from the current you draw will be R * I, R being the internal resistance of your entire battery pack, I being the current drawn from the pack. Use that to find out how much horsepower you can get on the battery side of the equation. A 240V string of 20 Exide Orbitals can give over 400 maximum battery horsepower, while a 72V string of Trojan golf cart batteries, only 30 or so maximum battery horsepower. Sealed batteries like Optima D750s can output over 1200 battery amps before they sag to 2/3 of their nominal voltage, while floodeds will generally only output 400 amps before their voltage sags to 2/3 of nominal voltage. Your needs for top speed and acceleration will determine your battery. As a general rule of thumb, the higher voltage your battery pack, the higher your top speed will be, and the higher amps your batteries can put out, the faster your acceleration will be. This is by no means a law of science, but it is a good indicator of how a conversion might perform. Many on-road 72V conversions of compact cars and small pickup trucks might top out at 50 mph, while a 156V conversion of the same vehicle might hit 90 mph. A more aerodynamic car will go faster on less power than the car it is compared with.
Here's a chart giving the cycle life, cost, and Peukert's numbers for a wide array of electric vehicle batteries:
http://www.geocities.com/CapeCanaver...9/battery.html
The lower the discharges you put on the battery, the more miles and cycles the battery will generally last. You don't want to discharge lead acid batteries below 80% because that will result in shortened life. Lead acid batteries have a shelf life of 6-7 years, usually miles will be the limitation that causes replacement, but shelf life will be if you size the pack accordingly so you're not discharging it too much.
3) Motor(s). Do you just want to be able to go highway speeds and don't care how long it takes to accelerate there, or do you want to go fast and want neck-snapping acceleration and high top speed? How much are you willing to spend? How much range you want? This will affect your motor choice. There are two main types used in electric cars: series DC motors and permanent magnet AC motors.
Series DC motors can make lots of torque for high performance and are very cheap. Torque varies as an exponent of the armature current, exponent varies as current draw increases. At zero amps the exponent is two and as it rises it heads to one. It can be modelled by the equation:
T = k*i^n
T is the torque produced, k is the constant representing the motor's size, field properties, coils, ect., and i is the current going through the motor, and n is the exponent.
With the right controller, DC motors can be VERY powerful, although they can also suit a budget conversion just fine.
Their drawbacks is that they are less efficient than AC motors by like 5%, cannot make use of regenerative braking, and need brush changes about every 15,000 miles. The brush change is no big deal: it takes 15 minutes and about $10. They also lack in high RPM horsepower thus giving you a more limited top speed than an AC motor. Unless you're racing, this is no worry. A DC motor still has absolutely no problem allowing an electric car to hit 90 mph. Proper gearing and high enough motor voltage can also allow high top end(Such as my conversion, which could end up hitting over 140 mph after I finish it).
Most often, the DC motors people use are 8'' or greater in diameter. Any smaller and power becomes an issue for highway speeds.
AC motors can be thousands of dollars more expensive than an AC motor due to their complex inverters. But, they will be efficient enough to give you about 5% more range, or up to 30% more if you do a lot of city driving because they allow regenerative braking. AC motors are limited in power by their inverter and horsepower does not come cheap. A 110 horsepower setup from Metric Mind Engineering would set you back about $2-4k more than a comparable DC setup. However, they provide a lot more higher rpm horsepower than a DC motor and can allow for great top speeds.
4) Controllers. This only applies to DC motors as any AC motors worth using come with their pricey inverters. Do you want to go fast or do you just want to be able to go the speed limit? What kind of batteries are you using, flooded or sealed? Want to either go fast like a Porsche or at least accelerate as fast as a normal car like a Ford Taurus? Get yourself a Cafe Electric Zilla, which is about $800 more than the slow option. The Zilla comes in many varieties, their basic one allowing a maximum battery pack voltage of 156V and allowing a maximum of 1,000 amps to be output to the motor and 1,000 amps to be drawn from the batteries. The user can set the limits. The slow option is the Curtis controller. It allows output of either 400, 500, or 550 amps to the motor depending on which controller, which isn't much. It also has two main varieties for highway capable electric vehicles, 120 max volts or 144 max volts. Use the Curtis if you don't care about speed. The other option is to use DCP Controllers which are no longer made and hard to find parts for, but they often turn up for cheap. DCP makes a 156V 600 amp controller, a 156V 1200 amp controller, and a 300V 1,000 amp controller. If you want to accelerate like a normal car, you'll either want a very light car < 2,500 pounds and at least 600 amps and 156V, or if you want a larger car to accelerate like normal, count on no less than 800 amps, or looking at a Zilla controller or a higher end DCP system. There are also comparable controllers made a Auburn as well that you might want to look into.
5) Chargers. What kind of battery are you using? Flooded? Almost any kind of charger will do, as floodeds can take abuse. Sealed? You'll want a Manzanita Micro PFC charger that allows you to input the proper charging algorithms to prevent battery damage. If you're using a Metric ind system, a Brusa charger is also not a bad option that allows you to set the proper charging algorithm. Non-lead chemistry? Either a custom-built PFC fitted to your needs if a DC conversion(You'll have to contact Rich Rudman personally and tell him of the batteries you will use the charger for), or a Brusa if metric mind AC system. PFC chargers and Brusa chargers are expensive, while if you use flooded lead acid batteries, you can use a cheap charger.
6) Calculations. Calculate how your vehicle will perform range and performance wise if you want to know those things before hand. For acceleration and top speed, it would be helpful to develop a spreadsheet to calculate that. Same for range. What is very convenient is that Uve Rick has already built a reasonably accurate range calculator. You can input your battery type, motor choice, ect., and calculator your car's range and top speed in each gear parameters.
http://www.geocities.com/hempev/EVCalculator.html
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III) You need to know where to look if you are considering doing a conversion.
If ANY of you are seriously considering a conversion, these resources are valuable:
Internet:
EV Discussion List: http://www.evdl.org/help/, This is the most valuable thing you could use if converting. This is where people from around the world discuss electric vehicle technology and its implications, and answer questions about converting cars to electric and help people through the process. They don't like discussing politics, as plenty of people of all views are there, and they prefer to keep it on topic about EVs. Converting a car? Join the list and don’t be afraid to dive in and ask questions. It will help you a ****load.
Check www.austinev.org, and take a look at people's conversions to get an idea of what's possible for a hobbyist to build. That link has over 300 cars that you can look at, plus motorcycles, scooters, and even electric lawnmowers. Owners list their specs such as top speed, range, and conversion cost, along with the parts they use. Don't be intimidated, high school kids have built EVs on their own. It's not that difficult, just time consuming, requires lots of planning, and takes money.
Go to www.nedra.com to see electric cars kicking ass on the racetracks.
http://www.eaaev.org/ gives you a lot of general purpose information on electric vehicles.
Books:
"Build your Own Electric Vehicle" by Bob Brant: Details all of the calculations you would use in designing your conversion, and gives you tips on selecting the chassis and components to meet your needs. The technology covered in the book is a little outdated, BUT it is still extrmely relevent for use. Don't pass it up.
"Convert It" by Mike Brown. Covers the process of converting a car in-depth, step by step. You'll want this if you're building an EV. Covers what is needed to keep your car roadworthy and safe.
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IV) Here are some places you can buy parts for EVs from(This is by no means all-inclusive, but a good list):
http://www.grassrootsev.com- Controllers, motors, other parts, and Steve Clunn sells already assembled conversions.
http://www.evparts.com/firstpage.php- Everything you need for an EV except car-suitable batteries.
http://www.electroauto.com- Sells bolt in kits for vehicles like the VW Rabbit, along with individual parts. Also sells Solectria AC drives.
http://www.metricmind.com- Sells AC Drives and Brusa chargers. Expensive but very good parts.
http://www.ev-america.com/- Another parts store.
http://www.canev.com/- A parts store for Canadians.
http://www.cloudelectric.com/- Another parts store.
http://www.evsource.com/- Sells Zilla controllers made by Café Electric.
http://www.kta-ev.com/- Sells parts and bolt-in kits.
http://www.go-ev.com- Great source of 8’’, 9’’, and 11’’ DC motors. Nothing comes close to their quality and they are cheaper than the inferior motors made by Advanced DC.
http://www.manzanitamicro.com/- Your source for the Power Factor Corrected charger, which is much more efficient than a Lester or a Russco, having 92% average efficiency instead of the 75% efficiency or so of a budget charger. Some PFC chargers also allow fast charging with the right outlet.
http://www.trojan-battery.com/- Trojan golf cart flooded lead acid batteries can be ordered direct from their site. They are an excellent option for inexpensive highway capable conversions.
http://www.usbattery.com/- Like Trojan, this is another widely used flooded lead acid battery for conversions.
http://www.exideworld.com/products/a...bital_XCD.html- Exide Orbital batteries. These are what you want for an EV that is anywhere from normal performance to a full-fledged suicide machine with too much horsepower for its own good.
http://www.austinev.org/evtradinpost/- This is the EV Trading post. If you don’t feel like building your own electric car and would rather buy a conversion someone else built, this is an excellent place to look. This is also an easy means to pickup used parts for cheap and safe a lot of cash on the conversion.
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V) I'm going to give you examples of a few conversions and how they would perform with a parts tally and cost analysis of the electric car versus a gasoline-powered Honda Civic.
Compact Car example:
First, I'll cover a cheap conversion of, say, a Geo Metro hatchback, using a WarP 8 series DC motor, 120V pack of Trojan T-875 12V batteries, Curtis 1231 C-7701 controller, and Rusco 30-120C Charger. Something basic in terms of utility, but with the things a normal car would have, like a gauge to tell you how much 'fuel' you might have, a heating element for winter, ect. Top speed at about 70 MPH, accelerates from 0-60 in about 20 seconds, 32-34 mile range at 50 MPH to 80% depth of discharge, 45-48 mile range at 40 MPH to 80% DoD, and could charge in 8-10 hours from a 110V outlet from 20% to 100%.
Here will be a tally for the parts such a conversion might use, with price and weight:
-WarP 8'' series DC motor x1 $1,225
-Trojan T-875 12V batteries x15 $960
-Curtis 1221 C-7401 controller(400 amp) x1 $995
-Russco 18-120C Charger(1800 watts) x1 $690
-CC Power Electronics 200W DC-DC converter(Headlights, wipers, radio, ect.) x2 $700
-Steel for battery racks $100
-Battery Cable $100
-EV200AAANA contactors x1 $75
-L25S-500 Littlefuse Safety Fuse(250 V, 500 amp) x3 $120
-Curtis Potbox(To control acceleration) x1 $75
-E-Meter x1 $235
-Solid-State Ceramic Heater Core x1 $75
-Adaptor Plate x1 $1000(approxamate, depending on who machines it. If you machine it yourself, it's simply a matter of the block of aluminum and your own labor)
-Miscallaneous components(Heat shrink tubing, ect.) $800
Total: $7,150 in parts, assuming converter does own labor except for machining adaptor plate to transmission and no restoration or repair of car. Does not include cost of the Geo Metro itself.
Lets compare cost of operation.
The flooded battery pack would last you about 30,000 miles or so if you discharge it about halfway for most of your trips, or up to 5 years or so, whichever comes first. $960 for 30,000 miles life is a battery pack cost of $.032 per mile. At $.08 per kWh of electricity achieving 200 wh/mile efficiency with a 75% charger efficiency and 70% battery efficiency, with $.005 per mile maintenance, total cost to operate comes out to $.06748 per mile, which combined is the same as the gasoline cost alone for a gasoline powered Honda Civic getting 30 miles per gallon with gas at $2 a gallon. Plus the Civic also needs oil changes, tune ups, servicing, emissions tests, and other engine maintenance, while the electric car has no such issues other than tires/brakes and stuff like that. The electric car? Replace the batteries when they wear out, and change the motor brushes every 20,000-150,000 miles(Depending on how you abuse them in racing), which is a $15 dollar 20 minute operation you can do yourself in your own garage. The electric motor will last over 500,000 miles. The maintenance on that Civic is about $.05 per mile, so that conversion will pay itself off in 9 years in savings.
Total cost of electric Metro per mile is $.06748
Total cost of gasoline Civic per mile is $.11666
Overall, this is a very basic conversion that has the amenities you'd expect from a normal car except air conditioning. It will perform about like a 60s VW Bug, and do highway speeds with ease, and have a realistic 30 mile range to 80% discharge of your battery pack. This is without extensively modifying the body of the car to improve aerodynamics, weight, cut drag, ect. Doing those things could be a cheap way to double the range.
Sports Car example:
Second, is my conversion, a high performance sports car. This is will be a high performance machine capable of 140 mph and 0-60 mph in 6 seconds, about like a Porsche Boxter or Audi TT. Range is going to be about 80-100 miles per charge. Charge time would be limited by outlet. 7 hours from 20% to 100% from a 110V outlet, 90 minutes from a 220V outlet like what you’d find at some camp grounds.
-WarP 9'' series DC motor x1 $1,395
-Optima D750 YT battery x25 $2,500
-Godzilla Controller(72-300V DC, 1,000 amp max) x1 $2,495
-PFC 20 Charger x1 $1,500
-Todd DC-DC converter x1 $400
-Steel for battery racks $50
-Battery Cable $50
-EV200AAANA contactors x1 $75
-Feraz Shawmut A50QS400-4 fuse x2 $109
-Curtis Potbox(To control acceleration) x1 $75
-E-Meter x1 $235
-Solid-State Ceramic Heater Core x1 $75
-Adaptor Plate x1 $1000(I will be machining myself, so don't count cost)
-Miscallaneous components(Heat shrink tubing, tools, ect.) $500
-Leaf springs from Renegade Hybrids $300 (increase GVWR)
-Rudman Battery Regulators x25(Unassembled) $250
-x1 1969 Triumph GT6 Sports Car and some restoration = $1,200
-restoration and components costs, what will be spent later: $1,500 (half for restoration, half for fiberglass parts)
Total = $12,709. My own labor is free, so not tallied. Includes cost of car.
Again with the cost analysis:
$2500 for 60,000 miles life is a battery pack cost of $.0417 per mile. At $.08 per kWh achieivng 150 wh/mile efficiency with a 92% charger efficiency and 70% battery efficiency, with $.005 per mile maintenance, total cost to operate comes out to $.0653 per mile, which combined is slightly less than the gasoline cost for a gasoline powered Honda Civic getting 30 miles per gallon with gas at $2 a gallon. The electric motor will last over 500,000 miles.
So, with my 100 miles range, assuming I drive 30 miles each day(my daily commute in both directions, 15 miles each way), would yield a 30% discharge, or a battery pack life of 60,000 miles before the battery pack has about 80% of its original rated capacity. A smaller battery pack of the same chemistry would mean for that same trip a deeper discharge is had, the cost per mile goes up. Too deep a discharge could kill your battery pack(although you can use computer software to prevent the operator of the vehicle from being able to do this). At shallow discharges like 20-40%, shelf life becomes the limiting factor, instead of cycle life, and Optimas have a shelf life of 6-7 years.
Total cost of electric Triumph per mile is $.0653
Total cost of gasoline Civic per mile is $.11666 (Gas and $.05/mile maintenance)
Pickup Truck example:
Third, lets model a decent range pickup truck like a Chevy S10 built for 40-50 miles highway range to 80% discharge with flooded lead acid batteries. It will be able to hit 85 mph, 0-60 about 15 seconds with more powerful controller and 0-30 mph faster than a gas S10 so about a normal performing vehicle. The power will be limited by the batteries. However, it’s pulling torque will be extraordinary, easily capable of pulling stumps out of the ground and for towing. The batteries would be setup in a single string of 156V. The charge time would be approximately 8 hours from a 110V outlet, 3 hours from a 220V outlet.
-WarP 9'' series DC motor x1 $1,395
-Trojan T-105 6V flooded lead acid battery x26 $1,430
-Godzilla Controller(72-156V DC, 1,000 amp max) x1 $1,950
-Russco SC 50-240 Charger(5000 watts) x1 $1090
-CC Power Electronics 200W DC-DC converter(Headlights, wipers, radio, ect.) x2 $700
-Steel for battery racks $100
-Battery Cable $100
-EV200AAANA contactors x1 $75
-L25S-500 Littlefuse Safety Fuse(250 V, 500 amp) x3 $120
-Curtis Potbox(To control acceleration) x1 $75
-E-Meter x1 $235
-Solid-State Ceramic Heater Core x1 $75
-Adaptor Plate x1 $1000
-Miscellaneous components(Heat shrink tubing, ect.) $800
Total cost: $9,245, again, all your own labor not tallied in price, except for labor for adaptor plate, and no inclusion of the cost of the truck itself.
Again, time for the cost analysis:
The flooded battery pack would last you about 36,500 miles or so with 730 cycles to 80% discharge if, or up to 5 years or so, whichever comes first. $1430 for 36,500 miles life is a battery pack cost of $.0391 per mile. At $.08 per kWh of electricity achieving 300 wh/mile efficiency with a 75% charger efficiency and 70% battery efficiency, with $.005 per mile maintenance, total cost to operate comes out to $.08981 per mile.
Total cost of electric S10 per mile is $.08981
Total cost of gasoline Civic per mile is $.11666
This truck going 50 miles a day would be going over 18,000 miles per year. Cut the depth of discharge of the batteries significantly with a shorter commute, and you cut the cost a lot!
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VI) An energy efficient vehicle is going to go farther for each pound of battery than a not so energy efficient vehicle.
You may want to take a look at increasing the efficiency of your vehicle if you choose to convert, as that can double or even triple your range without adding any batteries. You increase efficiency by reducing drag. Specifically, aerodynamic drag, rolling drag, wheel bearing drag, steering/brake drag, and transmission drag.
Aerodynamic drag:
aerodynamic drag force = 1/2 x rho x area x coefficient drag x velocity x velocity
Aerodynamic drag force is expressed in pounds, rho is the air density in slugs per cubic foot, area is the car's cross-sectional area in square feet, coefficient drag is the car's coefficient drag, velocity is the car's velocity expressed in feet per second.
The biggest gain in efficiency can be made by cutting aerodynamic drag. The rear body of a car contributes to about 30-35% of aerodynamic drag. Wheel wells 19-22%. Underbody, 13-16%. Front body, 10-14%. Projections and indentations, 6-10%. Engine compartment, 5-8%.
There isn't much you can do to change the front and rear body of the car. A front air dam could keep air from going into the underside of the car helping to reduce drag. The rear wheel wells can easily be covered. A full bellypan can be installed. The passenger side mirror can be removed, and a more aerodynamic mirror can replace the drivers' side mirror. Or the mirrors could be bypassed altogether and replaced with cameras, that display the rear view via LCD displays inside the car. The engine compartment can be mostly sealed, except with a small vent from the bottom of the car to allow hot air to be sucked out. Side skirts can also be added along with the car lowered so as to induce some semblance of laminar flow on part of the car. All seams can be taped up to cut skin friction. Smooth wheel covers will slightly cut the creation of turbulence, but not much. These modifications can be done without needing to redesign the car.
Also, a more steeply raked windshield will help drastically, but couldn't be implemented without drastically changing the body of the car itself. The optimized rear would taper back like a rain drop. These changes in style the industry itself could implement as well.
The following article illustrates perfectly the importance of reducing aerodynamic drag.
http://www.evworld.com/view.cfm?sect...le&storyid=870
The 1994 Toyota T100 pickup in that article, through improving the aerodynamics alone and nothing else, saw his highway fuel economy increase from 25 miles per gallon to 32 miles per gallon. Coefficient of drag was cut from .44 to .25.
Rolling Drag:
Rolling drag is almost as significant as aerodynamic drag when it comes to power consumption. It is proportional to vehicle weight.
Rolling resistance = cR x vehicle weight x sin(gradient) + cR x vehicle weight
Rolling resistance is the rolling drag in pounds. cR is the coefficient of rolling resistance of the tires, while the vehicle weight is expressed in pounds. Gradient is expressed in degrees, but for practical purposes, keep it zero for flat ground.
Typical radial tires have a cR value of about .009. A low rolling resistance tire like what is placed on a Honda Insight will have a cR value of about .006. An offroad tire of which you might find on a truck or SUV would be about .012. Choosing a low rolling resistance tire helps reduce the rolling force drastically.
So too, does reducing vehicle weight through use of composite body materials and through stripping the interior. Stripping the interior could allow one to remove over 400 pounds from a car, believe it or not! The cars we have today increased in weight because of the manufacturer's loading the interiors with useless trim of which they use as an excuse to inflate the price of the vehicle. This is despite the fact that cars today use lighter body materials than cars of the past! Fiberglass aftermarket parts are readily available to place on your car, but beware. Some may increase your weight if they aren't properly constructed, while others could drastically reduce it. Fiberglass body panels could reduce a Focus another 400 pounds in weight. Carbon fibre isn't available for an affordable price because the defense industry has a monopoly on it, but it certainly could be made to be affordable and placed in our cars today. Carbon fiber could reduce car weights by over 600 pounds for a Focus sized car. Wheels are also something that could be changed to reduce weight.
Reduced weight reduces energy consumption most especially during acceleration.
Wheel Bearing Drag:
Wheel bearing drag = bearing load x fR x bearing bore x wheel rpm
Wheel bearing drag is expressed in pounds, fR is the friction factor which is about .0016-.0021, bearing bore is the bore in inches(About 1.2 inches, but you can measure youself, varies by car), bearing load is the weight on the wheel bearing(total weight of car divided by 4), and rpm is the wheel rpm, which you can find based on your velocity, tire size, and gear ratio.
Cutting wheel bearing drag is as simple as replacing your wheel bearings with lower friction bearings or with a smaller bore.
Other gains can be made by using lighter wheels, which will cut down on the bearing load and cut down on inertia losses.
Steering/Brake Drag:
Adjust your alignment to zero degrees camber to cut steering drag. Machine your brake pistons to be perfectly round to cut brake drag.
Transmission Drag:
A typical transmission, drive shaft, and drive axel are about 85-90% efficient, combined as a full system. Running a synthetic transmission oil like Redline MTL(just an example) could improve this by 1-2%. Thus your fuel economy improves an extra 1-2%.
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VII) There are areas of interest associated with the EV.
If you’re interested in electric vehicle racing or electric vehicles built for performance, check the following topic:
http://www.peakoil.com/fortopic8987.html
If you are interested in the politics and environmental implications surrounding the electric vehicle, along with common electric vehicle myths, check the following topic:
http://www.peakoil.com/fortopic8972.html
Any questions? I’ll gladly answer.
I posted this on the peakoil.com forums a while back.
http://www.peakoil.com/fortopic9721.html
A few here at the pavilion have PMed me for info on how to build an electric car and where to look for parts many months ago. Just in case people have questions again, this topic will therefore be made. I want to provide the most useful info I can to the best of my ability. Without further ado, here it is.
***NOTE: This was written when gas was about $2/gallon. The comparison between electric and gas uses $2/gallon. At $3.50 today, the electric car offers even more savings.
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So, you want to build an electric car, or are at least interested in building an electric car? I apologize for the grossly long topic, but this post only touches the surface of this subject and is by no means in-depth, but I chose to include information that I felt would be relevent to someone new to the subject with minimal skills when it comes to working on cars.
This topic is divided into six sub topics:
I) How will you use your EV and what sort of EV will you choose to make.
II) How to go about researching the parts you need and how to build the car, and how to figure out what to expect of the car’s performance in range and acceleration.
III) Internet and literature on electric vehicles
IV) Where to buy parts
V) Specs and cost analysis of three conversion examples(Compact, sports car, and pickup)
VI) Maximizing vehicle efficiency
VII) Other areas of interest(electric car myths and politics, electric car racing)
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I) First thing is first, you need to ask yourself the following questions:
1) How much am I willing to spend? Expect to spend at least $5,000 for a basic highway capable conversion, probably $6-8k for a typical conversion, or higher at $10k on up or so if you want a go fast EV or a long range cruiser. Does not include cost of the chassis you choose to use. You might think that is expensive, but many of the parts you will use are hand-made. It’s all about production volume.
2) What kind of car do I want? Midsize, compact, pickup, sports car, wagon, SUV? What are my utility needs? Will I be satisfied with the car and want to keep it? Choose a car you like and a car that will suit your needs. A sports car may not have a lot of battery room, but a pickup will have a ****load of it. Likewise, that pickup may not be anywhere near as energy efficient as that sports car.
3) How much range do I need? How much range do I want? Lead acid is the only 'affordable' battery right now, due to reasons of politics on some chemistries and low production volume relative to automotive application on others. Lead acid can easily do 40-60 miles per charge for a typical run of the mill conversion, 100 or more in an efficient vehicle or a pickup truck loaded with almost half its weight in batteries. If you're willing to hand build a battery pack for $30,000 or more, you could do Lithium Ion and have 300 miles range, but since electric cars aren't produced along with automotive sized lithium batteries, you'll be on your own or excessively wealthy if you want a hand-built lithium battery pack from thousands of laptop batteries. With lead acid batteries, cold weather affects range. If it's freezing outside, your lead acid battery will only deliver about half the range you'd normally get, unless you have a heating system to keep it warm, which will then allow you full capacity.
4) How much work am I willing to do? A conversion will take anywhere from 100 hours work for a basic conversion to 500 hours or more to a dedicated race car or efficiency perfected long range cruiser. This doesn't count research.
5) WHY do you want the car? Here's a list of reasons why one might use an EV:
a) Want a means of transportation that doesn't support despotic regimes in the middle east
b) Want a cheap way to have a fast car
c) Want a car that doesn't cost much to run
d) Want to reduce environmental impact of a 1st world lifestyle
e) Want a means to get energy for a car from renewable fuels(Solar, wind, ect.)
f) Want a car that will last for life(Barring accidents, tornados, ect.)
g) Want a car that will always start in the morning, even on a cold winter day
h) Want to avoid rising gas prices
i) Want to boycott auto monopolies
j) Want to embarrass V8s with torque out of this world
k) If your power goes out you can keep your lights, TV, refrigerator, ect. going with your car.
l) It offers a means to power your transportation with wind or solar energy.
This list is by no means all-inclusive. Some reasons work well for some, other reasons for others. What do you want out of the car? Why would you want to drive an electric car?
6) What ancillaries do you want? Heating, air conditioning, high output stereo system? All these things add cost. You can choose to run them off a 12v battery and have to recharge that individual battery with your battery pack, or choose to use a DC to DC converter so that you don’t have to worry about an extra battery.
7) What kind of maintenance are you willing to do? Electric cars need virtually none, but flooded batteries will need to be watered about every 2,000 miles with distilled water and cleaned as often to prevent corrosion, while sealed lead acid batteries will not. Are you willing to water a set of batteries to save even more money, or would you rather have a hands off approach? Use tap water on flooded batteries and the metals in the tap water will ruin them.
8) What are your performance goals? Flooded lead acid batteries don't have the power to let you go fast, while sealed lead acid batteries do. Sealed lead acid batteries are more expensive than floodeds.
Other options if you don’t want to covert a car is to buy a used conversion. However, labor went into that conversion which you will have to usually pay for and used conversions are usually built on old chassis so you will likely not find such an endeavor worth it.
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II) Second, is research. You'll be doing a lot of that before you begin building.
1) Find the chassis types that will fit your needs. Parameters you need to look for:
a) Dry weight- How much the car weighs with all fluids, spare tires, and people removed. This will affect your rolling resistance. Lower weight means lower rolling resistance and thus more efficiency and greater range per pound of battery.
b) Drag Coefficient- How much resistance your car's shape poses to outside air. Lower coefficient of drag means less drag force is induced on the vehicle at speed, meaning greater efficiency and more range.
c) Frontal Area- Cross sectional area of the vehicle. Smaller is better. To estimate it, take width times height times .8. Smaller frontal area means less drag and thus more range per pound of battery.
d) Cost- How much does the chassis cost?
e) Condition- What shape is the chassis in? How much will it cost to repair it to a point where you will be happy with it?
f) Reliability- Does the car have reliable brakes, wipers, ect., and if it doesn't would you be happy with it as is or willing to fix it to be more reliable?
g) Battery room- How much overall space do you have to place batteries?
h) Rarity/commonality- Will you even be able to find the car, or parts for it should something break?
i) Gear ratios and transmission- This will affect how fast you will be able to go. Will the ratio allow me to have the top speed I want with the max motor RPM of the electric motor I wish to use? Can the transmission handle the torque I will deal to it with the motor and controller combination, or will I need to bolt in a transmission that is stronger?
j) Gross Vehicle Weight Rating(GVWR)- This is the weight your vehicle can withstand before it becomes unsafe because of elongated braking distances and changed handling characteristics. You'll need a high GVWR in contrast to dry weight because you'll be stuffing in a lot of battery weight. You can exceed GVWR, and install leaf springs to keep your suspension from sagging, but you won't want to go more than 200 pounds over, including weight of driver and passengers.
2) Batteries. Flooded lead acid or sealed lead acid? Lithium ion or nickel cadmium instead? This will be based on your needs for range, performance, and cost. Flooded lead acid batteries provide better low speed range per pound than sealed lead acid batteries, and sealed more high speed range per pound than flooded. As a general rule, if you're going to use all your car's range in less than an hour, sealed will give you better range per pound, and if you'll use all the range in more than an hour flooded will give you more range per pound. Flooded lead acid batteries are poor on power and will not allow you to accelerate like a normal car. Sealed have more power than you'll ever need and can allow you to out accelerate Ferraris with the right motor and controller combination. Want to perform like normal and not either of the extremes? You'll want sealed. Just want to go highway speeds and don't care about speed? Flooded would suit you fine. Per mile, sealed lead acid batteries are the most expensive battery, flooded lead acid are the cheapest lead acid, and other batteries true costs aren't realized because they are not produced in the volume of lead acid, but often exotic chemistries like nickel cadmium are more expensive up front but cheaper per mile because of their long lifespan. Lead acid batteries further suffer from Peukert's effect, which means that they won't get their 20 hour rated capacity out of them at higher rates than taking 20 hours to discharge the battery.
The equation for Peukert's effect is as follows:
(I^n)*T = C
C is a constant called Peukert's capacity. It is akin to the total number of amp hours a battery can deliver at a current draw of 1 ampere. However, the unit itself is not expressed in amp hours due to the exponent.
I is the average current draw of the battery in amperes.
n is Peukert's exponent, how much the effect applies to the lead acid battery in question. Sealed generally have an exponent around 1.05 to 1.15. Flooded are generally around 1.2 to 1.4.
T is the time in hours the battery will deliver the current I.
Batteries don't come with Peukert's exponent and Peukert's capacity labelled on them. You have to solve them. Batteries are rated at the 20 hour rate in amp hours and at the 25 amp rate in reserve capacity, reserve capacity being the total number of minute the battery can deliver 25 amps. Using logarithms allows one to solve for the Peukert's numbers.
For power, you want low internal resistance. Power in kW = volts * amps
Your voltage drop from the current you draw will be R * I, R being the internal resistance of your entire battery pack, I being the current drawn from the pack. Use that to find out how much horsepower you can get on the battery side of the equation. A 240V string of 20 Exide Orbitals can give over 400 maximum battery horsepower, while a 72V string of Trojan golf cart batteries, only 30 or so maximum battery horsepower. Sealed batteries like Optima D750s can output over 1200 battery amps before they sag to 2/3 of their nominal voltage, while floodeds will generally only output 400 amps before their voltage sags to 2/3 of nominal voltage. Your needs for top speed and acceleration will determine your battery. As a general rule of thumb, the higher voltage your battery pack, the higher your top speed will be, and the higher amps your batteries can put out, the faster your acceleration will be. This is by no means a law of science, but it is a good indicator of how a conversion might perform. Many on-road 72V conversions of compact cars and small pickup trucks might top out at 50 mph, while a 156V conversion of the same vehicle might hit 90 mph. A more aerodynamic car will go faster on less power than the car it is compared with.
Here's a chart giving the cycle life, cost, and Peukert's numbers for a wide array of electric vehicle batteries:
http://www.geocities.com/CapeCanaver...9/battery.html
The lower the discharges you put on the battery, the more miles and cycles the battery will generally last. You don't want to discharge lead acid batteries below 80% because that will result in shortened life. Lead acid batteries have a shelf life of 6-7 years, usually miles will be the limitation that causes replacement, but shelf life will be if you size the pack accordingly so you're not discharging it too much.
3) Motor(s). Do you just want to be able to go highway speeds and don't care how long it takes to accelerate there, or do you want to go fast and want neck-snapping acceleration and high top speed? How much are you willing to spend? How much range you want? This will affect your motor choice. There are two main types used in electric cars: series DC motors and permanent magnet AC motors.
Series DC motors can make lots of torque for high performance and are very cheap. Torque varies as an exponent of the armature current, exponent varies as current draw increases. At zero amps the exponent is two and as it rises it heads to one. It can be modelled by the equation:
T = k*i^n
T is the torque produced, k is the constant representing the motor's size, field properties, coils, ect., and i is the current going through the motor, and n is the exponent.
With the right controller, DC motors can be VERY powerful, although they can also suit a budget conversion just fine.
Their drawbacks is that they are less efficient than AC motors by like 5%, cannot make use of regenerative braking, and need brush changes about every 15,000 miles. The brush change is no big deal: it takes 15 minutes and about $10. They also lack in high RPM horsepower thus giving you a more limited top speed than an AC motor. Unless you're racing, this is no worry. A DC motor still has absolutely no problem allowing an electric car to hit 90 mph. Proper gearing and high enough motor voltage can also allow high top end(Such as my conversion, which could end up hitting over 140 mph after I finish it).
Most often, the DC motors people use are 8'' or greater in diameter. Any smaller and power becomes an issue for highway speeds.
AC motors can be thousands of dollars more expensive than an AC motor due to their complex inverters. But, they will be efficient enough to give you about 5% more range, or up to 30% more if you do a lot of city driving because they allow regenerative braking. AC motors are limited in power by their inverter and horsepower does not come cheap. A 110 horsepower setup from Metric Mind Engineering would set you back about $2-4k more than a comparable DC setup. However, they provide a lot more higher rpm horsepower than a DC motor and can allow for great top speeds.
4) Controllers. This only applies to DC motors as any AC motors worth using come with their pricey inverters. Do you want to go fast or do you just want to be able to go the speed limit? What kind of batteries are you using, flooded or sealed? Want to either go fast like a Porsche or at least accelerate as fast as a normal car like a Ford Taurus? Get yourself a Cafe Electric Zilla, which is about $800 more than the slow option. The Zilla comes in many varieties, their basic one allowing a maximum battery pack voltage of 156V and allowing a maximum of 1,000 amps to be output to the motor and 1,000 amps to be drawn from the batteries. The user can set the limits. The slow option is the Curtis controller. It allows output of either 400, 500, or 550 amps to the motor depending on which controller, which isn't much. It also has two main varieties for highway capable electric vehicles, 120 max volts or 144 max volts. Use the Curtis if you don't care about speed. The other option is to use DCP Controllers which are no longer made and hard to find parts for, but they often turn up for cheap. DCP makes a 156V 600 amp controller, a 156V 1200 amp controller, and a 300V 1,000 amp controller. If you want to accelerate like a normal car, you'll either want a very light car < 2,500 pounds and at least 600 amps and 156V, or if you want a larger car to accelerate like normal, count on no less than 800 amps, or looking at a Zilla controller or a higher end DCP system. There are also comparable controllers made a Auburn as well that you might want to look into.
5) Chargers. What kind of battery are you using? Flooded? Almost any kind of charger will do, as floodeds can take abuse. Sealed? You'll want a Manzanita Micro PFC charger that allows you to input the proper charging algorithms to prevent battery damage. If you're using a Metric ind system, a Brusa charger is also not a bad option that allows you to set the proper charging algorithm. Non-lead chemistry? Either a custom-built PFC fitted to your needs if a DC conversion(You'll have to contact Rich Rudman personally and tell him of the batteries you will use the charger for), or a Brusa if metric mind AC system. PFC chargers and Brusa chargers are expensive, while if you use flooded lead acid batteries, you can use a cheap charger.
6) Calculations. Calculate how your vehicle will perform range and performance wise if you want to know those things before hand. For acceleration and top speed, it would be helpful to develop a spreadsheet to calculate that. Same for range. What is very convenient is that Uve Rick has already built a reasonably accurate range calculator. You can input your battery type, motor choice, ect., and calculator your car's range and top speed in each gear parameters.
http://www.geocities.com/hempev/EVCalculator.html
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III) You need to know where to look if you are considering doing a conversion.
If ANY of you are seriously considering a conversion, these resources are valuable:
Internet:
EV Discussion List: http://www.evdl.org/help/, This is the most valuable thing you could use if converting. This is where people from around the world discuss electric vehicle technology and its implications, and answer questions about converting cars to electric and help people through the process. They don't like discussing politics, as plenty of people of all views are there, and they prefer to keep it on topic about EVs. Converting a car? Join the list and don’t be afraid to dive in and ask questions. It will help you a ****load.
Check www.austinev.org, and take a look at people's conversions to get an idea of what's possible for a hobbyist to build. That link has over 300 cars that you can look at, plus motorcycles, scooters, and even electric lawnmowers. Owners list their specs such as top speed, range, and conversion cost, along with the parts they use. Don't be intimidated, high school kids have built EVs on their own. It's not that difficult, just time consuming, requires lots of planning, and takes money.
Go to www.nedra.com to see electric cars kicking ass on the racetracks.
http://www.eaaev.org/ gives you a lot of general purpose information on electric vehicles.
Books:
"Build your Own Electric Vehicle" by Bob Brant: Details all of the calculations you would use in designing your conversion, and gives you tips on selecting the chassis and components to meet your needs. The technology covered in the book is a little outdated, BUT it is still extrmely relevent for use. Don't pass it up.
"Convert It" by Mike Brown. Covers the process of converting a car in-depth, step by step. You'll want this if you're building an EV. Covers what is needed to keep your car roadworthy and safe.
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IV) Here are some places you can buy parts for EVs from(This is by no means all-inclusive, but a good list):
http://www.grassrootsev.com- Controllers, motors, other parts, and Steve Clunn sells already assembled conversions.
http://www.evparts.com/firstpage.php- Everything you need for an EV except car-suitable batteries.
http://www.electroauto.com- Sells bolt in kits for vehicles like the VW Rabbit, along with individual parts. Also sells Solectria AC drives.
http://www.metricmind.com- Sells AC Drives and Brusa chargers. Expensive but very good parts.
http://www.ev-america.com/- Another parts store.
http://www.canev.com/- A parts store for Canadians.
http://www.cloudelectric.com/- Another parts store.
http://www.evsource.com/- Sells Zilla controllers made by Café Electric.
http://www.kta-ev.com/- Sells parts and bolt-in kits.
http://www.go-ev.com- Great source of 8’’, 9’’, and 11’’ DC motors. Nothing comes close to their quality and they are cheaper than the inferior motors made by Advanced DC.
http://www.manzanitamicro.com/- Your source for the Power Factor Corrected charger, which is much more efficient than a Lester or a Russco, having 92% average efficiency instead of the 75% efficiency or so of a budget charger. Some PFC chargers also allow fast charging with the right outlet.
http://www.trojan-battery.com/- Trojan golf cart flooded lead acid batteries can be ordered direct from their site. They are an excellent option for inexpensive highway capable conversions.
http://www.usbattery.com/- Like Trojan, this is another widely used flooded lead acid battery for conversions.
http://www.exideworld.com/products/a...bital_XCD.html- Exide Orbital batteries. These are what you want for an EV that is anywhere from normal performance to a full-fledged suicide machine with too much horsepower for its own good.
http://www.austinev.org/evtradinpost/- This is the EV Trading post. If you don’t feel like building your own electric car and would rather buy a conversion someone else built, this is an excellent place to look. This is also an easy means to pickup used parts for cheap and safe a lot of cash on the conversion.
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V) I'm going to give you examples of a few conversions and how they would perform with a parts tally and cost analysis of the electric car versus a gasoline-powered Honda Civic.
Compact Car example:
First, I'll cover a cheap conversion of, say, a Geo Metro hatchback, using a WarP 8 series DC motor, 120V pack of Trojan T-875 12V batteries, Curtis 1231 C-7701 controller, and Rusco 30-120C Charger. Something basic in terms of utility, but with the things a normal car would have, like a gauge to tell you how much 'fuel' you might have, a heating element for winter, ect. Top speed at about 70 MPH, accelerates from 0-60 in about 20 seconds, 32-34 mile range at 50 MPH to 80% depth of discharge, 45-48 mile range at 40 MPH to 80% DoD, and could charge in 8-10 hours from a 110V outlet from 20% to 100%.
Here will be a tally for the parts such a conversion might use, with price and weight:
-WarP 8'' series DC motor x1 $1,225
-Trojan T-875 12V batteries x15 $960
-Curtis 1221 C-7401 controller(400 amp) x1 $995
-Russco 18-120C Charger(1800 watts) x1 $690
-CC Power Electronics 200W DC-DC converter(Headlights, wipers, radio, ect.) x2 $700
-Steel for battery racks $100
-Battery Cable $100
-EV200AAANA contactors x1 $75
-L25S-500 Littlefuse Safety Fuse(250 V, 500 amp) x3 $120
-Curtis Potbox(To control acceleration) x1 $75
-E-Meter x1 $235
-Solid-State Ceramic Heater Core x1 $75
-Adaptor Plate x1 $1000(approxamate, depending on who machines it. If you machine it yourself, it's simply a matter of the block of aluminum and your own labor)
-Miscallaneous components(Heat shrink tubing, ect.) $800
Total: $7,150 in parts, assuming converter does own labor except for machining adaptor plate to transmission and no restoration or repair of car. Does not include cost of the Geo Metro itself.
Lets compare cost of operation.
The flooded battery pack would last you about 30,000 miles or so if you discharge it about halfway for most of your trips, or up to 5 years or so, whichever comes first. $960 for 30,000 miles life is a battery pack cost of $.032 per mile. At $.08 per kWh of electricity achieving 200 wh/mile efficiency with a 75% charger efficiency and 70% battery efficiency, with $.005 per mile maintenance, total cost to operate comes out to $.06748 per mile, which combined is the same as the gasoline cost alone for a gasoline powered Honda Civic getting 30 miles per gallon with gas at $2 a gallon. Plus the Civic also needs oil changes, tune ups, servicing, emissions tests, and other engine maintenance, while the electric car has no such issues other than tires/brakes and stuff like that. The electric car? Replace the batteries when they wear out, and change the motor brushes every 20,000-150,000 miles(Depending on how you abuse them in racing), which is a $15 dollar 20 minute operation you can do yourself in your own garage. The electric motor will last over 500,000 miles. The maintenance on that Civic is about $.05 per mile, so that conversion will pay itself off in 9 years in savings.
Total cost of electric Metro per mile is $.06748
Total cost of gasoline Civic per mile is $.11666
Overall, this is a very basic conversion that has the amenities you'd expect from a normal car except air conditioning. It will perform about like a 60s VW Bug, and do highway speeds with ease, and have a realistic 30 mile range to 80% discharge of your battery pack. This is without extensively modifying the body of the car to improve aerodynamics, weight, cut drag, ect. Doing those things could be a cheap way to double the range.
Sports Car example:
Second, is my conversion, a high performance sports car. This is will be a high performance machine capable of 140 mph and 0-60 mph in 6 seconds, about like a Porsche Boxter or Audi TT. Range is going to be about 80-100 miles per charge. Charge time would be limited by outlet. 7 hours from 20% to 100% from a 110V outlet, 90 minutes from a 220V outlet like what you’d find at some camp grounds.
-WarP 9'' series DC motor x1 $1,395
-Optima D750 YT battery x25 $2,500
-Godzilla Controller(72-300V DC, 1,000 amp max) x1 $2,495
-PFC 20 Charger x1 $1,500
-Todd DC-DC converter x1 $400
-Steel for battery racks $50
-Battery Cable $50
-EV200AAANA contactors x1 $75
-Feraz Shawmut A50QS400-4 fuse x2 $109
-Curtis Potbox(To control acceleration) x1 $75
-E-Meter x1 $235
-Solid-State Ceramic Heater Core x1 $75
-Adaptor Plate x1 $1000(I will be machining myself, so don't count cost)
-Miscallaneous components(Heat shrink tubing, tools, ect.) $500
-Leaf springs from Renegade Hybrids $300 (increase GVWR)
-Rudman Battery Regulators x25(Unassembled) $250
-x1 1969 Triumph GT6 Sports Car and some restoration = $1,200
-restoration and components costs, what will be spent later: $1,500 (half for restoration, half for fiberglass parts)
Total = $12,709. My own labor is free, so not tallied. Includes cost of car.
Again with the cost analysis:
$2500 for 60,000 miles life is a battery pack cost of $.0417 per mile. At $.08 per kWh achieivng 150 wh/mile efficiency with a 92% charger efficiency and 70% battery efficiency, with $.005 per mile maintenance, total cost to operate comes out to $.0653 per mile, which combined is slightly less than the gasoline cost for a gasoline powered Honda Civic getting 30 miles per gallon with gas at $2 a gallon. The electric motor will last over 500,000 miles.
So, with my 100 miles range, assuming I drive 30 miles each day(my daily commute in both directions, 15 miles each way), would yield a 30% discharge, or a battery pack life of 60,000 miles before the battery pack has about 80% of its original rated capacity. A smaller battery pack of the same chemistry would mean for that same trip a deeper discharge is had, the cost per mile goes up. Too deep a discharge could kill your battery pack(although you can use computer software to prevent the operator of the vehicle from being able to do this). At shallow discharges like 20-40%, shelf life becomes the limiting factor, instead of cycle life, and Optimas have a shelf life of 6-7 years.
Total cost of electric Triumph per mile is $.0653
Total cost of gasoline Civic per mile is $.11666 (Gas and $.05/mile maintenance)
Pickup Truck example:
Third, lets model a decent range pickup truck like a Chevy S10 built for 40-50 miles highway range to 80% discharge with flooded lead acid batteries. It will be able to hit 85 mph, 0-60 about 15 seconds with more powerful controller and 0-30 mph faster than a gas S10 so about a normal performing vehicle. The power will be limited by the batteries. However, it’s pulling torque will be extraordinary, easily capable of pulling stumps out of the ground and for towing. The batteries would be setup in a single string of 156V. The charge time would be approximately 8 hours from a 110V outlet, 3 hours from a 220V outlet.
-WarP 9'' series DC motor x1 $1,395
-Trojan T-105 6V flooded lead acid battery x26 $1,430
-Godzilla Controller(72-156V DC, 1,000 amp max) x1 $1,950
-Russco SC 50-240 Charger(5000 watts) x1 $1090
-CC Power Electronics 200W DC-DC converter(Headlights, wipers, radio, ect.) x2 $700
-Steel for battery racks $100
-Battery Cable $100
-EV200AAANA contactors x1 $75
-L25S-500 Littlefuse Safety Fuse(250 V, 500 amp) x3 $120
-Curtis Potbox(To control acceleration) x1 $75
-E-Meter x1 $235
-Solid-State Ceramic Heater Core x1 $75
-Adaptor Plate x1 $1000
-Miscellaneous components(Heat shrink tubing, ect.) $800
Total cost: $9,245, again, all your own labor not tallied in price, except for labor for adaptor plate, and no inclusion of the cost of the truck itself.
Again, time for the cost analysis:
The flooded battery pack would last you about 36,500 miles or so with 730 cycles to 80% discharge if, or up to 5 years or so, whichever comes first. $1430 for 36,500 miles life is a battery pack cost of $.0391 per mile. At $.08 per kWh of electricity achieving 300 wh/mile efficiency with a 75% charger efficiency and 70% battery efficiency, with $.005 per mile maintenance, total cost to operate comes out to $.08981 per mile.
Total cost of electric S10 per mile is $.08981
Total cost of gasoline Civic per mile is $.11666
This truck going 50 miles a day would be going over 18,000 miles per year. Cut the depth of discharge of the batteries significantly with a shorter commute, and you cut the cost a lot!
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VI) An energy efficient vehicle is going to go farther for each pound of battery than a not so energy efficient vehicle.
You may want to take a look at increasing the efficiency of your vehicle if you choose to convert, as that can double or even triple your range without adding any batteries. You increase efficiency by reducing drag. Specifically, aerodynamic drag, rolling drag, wheel bearing drag, steering/brake drag, and transmission drag.
Aerodynamic drag:
aerodynamic drag force = 1/2 x rho x area x coefficient drag x velocity x velocity
Aerodynamic drag force is expressed in pounds, rho is the air density in slugs per cubic foot, area is the car's cross-sectional area in square feet, coefficient drag is the car's coefficient drag, velocity is the car's velocity expressed in feet per second.
The biggest gain in efficiency can be made by cutting aerodynamic drag. The rear body of a car contributes to about 30-35% of aerodynamic drag. Wheel wells 19-22%. Underbody, 13-16%. Front body, 10-14%. Projections and indentations, 6-10%. Engine compartment, 5-8%.
There isn't much you can do to change the front and rear body of the car. A front air dam could keep air from going into the underside of the car helping to reduce drag. The rear wheel wells can easily be covered. A full bellypan can be installed. The passenger side mirror can be removed, and a more aerodynamic mirror can replace the drivers' side mirror. Or the mirrors could be bypassed altogether and replaced with cameras, that display the rear view via LCD displays inside the car. The engine compartment can be mostly sealed, except with a small vent from the bottom of the car to allow hot air to be sucked out. Side skirts can also be added along with the car lowered so as to induce some semblance of laminar flow on part of the car. All seams can be taped up to cut skin friction. Smooth wheel covers will slightly cut the creation of turbulence, but not much. These modifications can be done without needing to redesign the car.
Also, a more steeply raked windshield will help drastically, but couldn't be implemented without drastically changing the body of the car itself. The optimized rear would taper back like a rain drop. These changes in style the industry itself could implement as well.
The following article illustrates perfectly the importance of reducing aerodynamic drag.
http://www.evworld.com/view.cfm?sect...le&storyid=870
The 1994 Toyota T100 pickup in that article, through improving the aerodynamics alone and nothing else, saw his highway fuel economy increase from 25 miles per gallon to 32 miles per gallon. Coefficient of drag was cut from .44 to .25.
Rolling Drag:
Rolling drag is almost as significant as aerodynamic drag when it comes to power consumption. It is proportional to vehicle weight.
Rolling resistance = cR x vehicle weight x sin(gradient) + cR x vehicle weight
Rolling resistance is the rolling drag in pounds. cR is the coefficient of rolling resistance of the tires, while the vehicle weight is expressed in pounds. Gradient is expressed in degrees, but for practical purposes, keep it zero for flat ground.
Typical radial tires have a cR value of about .009. A low rolling resistance tire like what is placed on a Honda Insight will have a cR value of about .006. An offroad tire of which you might find on a truck or SUV would be about .012. Choosing a low rolling resistance tire helps reduce the rolling force drastically.
So too, does reducing vehicle weight through use of composite body materials and through stripping the interior. Stripping the interior could allow one to remove over 400 pounds from a car, believe it or not! The cars we have today increased in weight because of the manufacturer's loading the interiors with useless trim of which they use as an excuse to inflate the price of the vehicle. This is despite the fact that cars today use lighter body materials than cars of the past! Fiberglass aftermarket parts are readily available to place on your car, but beware. Some may increase your weight if they aren't properly constructed, while others could drastically reduce it. Fiberglass body panels could reduce a Focus another 400 pounds in weight. Carbon fibre isn't available for an affordable price because the defense industry has a monopoly on it, but it certainly could be made to be affordable and placed in our cars today. Carbon fiber could reduce car weights by over 600 pounds for a Focus sized car. Wheels are also something that could be changed to reduce weight.
Reduced weight reduces energy consumption most especially during acceleration.
Wheel Bearing Drag:
Wheel bearing drag = bearing load x fR x bearing bore x wheel rpm
Wheel bearing drag is expressed in pounds, fR is the friction factor which is about .0016-.0021, bearing bore is the bore in inches(About 1.2 inches, but you can measure youself, varies by car), bearing load is the weight on the wheel bearing(total weight of car divided by 4), and rpm is the wheel rpm, which you can find based on your velocity, tire size, and gear ratio.
Cutting wheel bearing drag is as simple as replacing your wheel bearings with lower friction bearings or with a smaller bore.
Other gains can be made by using lighter wheels, which will cut down on the bearing load and cut down on inertia losses.
Steering/Brake Drag:
Adjust your alignment to zero degrees camber to cut steering drag. Machine your brake pistons to be perfectly round to cut brake drag.
Transmission Drag:
A typical transmission, drive shaft, and drive axel are about 85-90% efficient, combined as a full system. Running a synthetic transmission oil like Redline MTL(just an example) could improve this by 1-2%. Thus your fuel economy improves an extra 1-2%.
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VII) There are areas of interest associated with the EV.
If you’re interested in electric vehicle racing or electric vehicles built for performance, check the following topic:
http://www.peakoil.com/fortopic8987.html
If you are interested in the politics and environmental implications surrounding the electric vehicle, along with common electric vehicle myths, check the following topic:
http://www.peakoil.com/fortopic8972.html
Any questions? I’ll gladly answer.
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