Build your own Electric Car!

The "Electro-Metro" Project.

Can't afford a Nissan Leaf? No Problem!

Build a cheap electric car yourself by removing the the car engine, replacing it with a forklift motor, and adding batteries.

I have plenty of videos about this project at:
http://www.youtube.com/user/BenjaminNelson
and 300MPG.org

The primary "build blog" for this project is at:
http://ecomodder.com/forum/showthread.php/ben-nelsons-electro-metro-build-thread-848.html
but watch out! That is a good read for when you have WAY too much time on your hands.

For a good intro to basic electric car construction, stick with this Instructable.

For more in-depth construction information, check out the DVD available at 300MPG.org

Step 1 Get a car.

The first thing you need to do is get a car. They are not all equal.

I was looking for something lightweight, with no power anything.

Heavier cars need more energy to push down the road, thus limiting your range on batteries.

Things like power steering and power brakes run off the engine, which is going to be removed anyways, rendering them useless. Power windows and locks add weight and complexity to the vehicle.

I ended up finding a Geo Metro for sale, for $500. The engine ran fine, and the body wasn't too bad, but I couldn't drive it home because the clutch was messed up. Oh well, this conversion isn't going to use a clutch anyways!

Make sure the car doesn't have anything major wrong with it (other than maybe a blown engine!) You want to do a Conversion, not a Restoration!

Comments

[fireproofshark]

brilliant project, i have an old beetle and was looking into trying to adapt a similar power brake system into it do you have any pics of the finished brake system setup and what sort of vacuum pressure was required?

[unstabelone]

hi my son and i are going to build an electric car. can we use a car with rear wheel drive ? like a 88 mustang. and does your car have power brakes or power stering ?

[bennelson]

Yes! You can use rear-wheel drive! In fact, it actually gives you a little more room in front for the motor.

An 80's Mustang would be great!

My car had manual steering, but power brakes. I added an electric vacuum pump to run the power brakes. Works fantastic.

[msihcs]

First let me say I am extremely impressed that you would take the initiative to actually do this type of project I have dreamed of it but never actually took the leap.

My background is mechanical engineering (operating steam plants in the Navy) I do have a question though. My relatively average knowledge of electronics would lead me to think that as long as the motors are identical and the current to them is regulated properly that you could use 4 smaller motors (one at each wheel) instead of one big one to propel the vehicle. If run in parallel the motors should all turn at the same speed (I am sure a computer could further regulate the current to keep the wheels within a certain range of each other)

I ask this because the price of motors that are 25+ hp are a little high for the average person to purchase for their first EV project this (as BigTurd suggested) would also cut the need for a full sized transmission.

[bennelson]

Yes, in theory, each of 4 motors would only have to do 1/4 the amount of work. I used the existing transmission in the car because the vehicle is already designed to run as front-wheel-drive. The transmission not only has the gearing, but it is also the differential and connects the "half-shafts" (sideways-traveling short drive-shafts) to the front wheels. The trouble with using four motors, one on each wheel, is that you will have to figure out where to mount each of those motors and how to connect it to each wheel.



In a brand-new, custom-built vehicle, it would be easy to design for. In fact, with the motors out of the way, and no traditional transmission, it would give you great design flexibility. Modern car manufacturers talk about that sort of thing all the time. But for a simple conversion of an existing car, just replacing the engine with an electric motor and adding batteries is far more straight-forward than designing/manufacturing/fabricating everything for multiple motors and driven wheels.



I think that a four-wheel-drive hub-motor vehicle would be a great project to see. It might start off best as an "off-road-only" vehicle, something like a dune-buggy, ATV or something similar.



The "Tropica" electric car, designed by Bob Beaumont, also the inventor of the Citicar, was rear-wheel drive with TWO electric motors. Each motor was mounted on the swing-arm of the wheel, along with a belt and pulley to get the gear ratio right from the motor to the wheel. Also, each of the two motors had its own controller.

As for the cost of motors. There are plenty of good ones that can be bought brand new, specifically for EV use for $1000-$3000. That was a little expensive for my project, which only cost about $1300 total. My motor was from an electric forklift. I bought it for $50, cleaned it up, and installed it in my car. It works great.



For more information on repurposing forklift motors to power electric cars, please visit this link.

[BigTurd]

Seems to me you could have saved a bit of power (range) by removing the transmission altogether. This cuts some HP loss thru the gears not to mention some weight etc.

The proviso being that the traction motor can reach the rpm's necessary for your type of driving conditions. If it can't, perhaps you can pop in a different rear end ratio that better suits your needs.

Another note, there's likely a way to use the motor for regenerative braking to charge the batteries. It won't completely recharge them but adds a little extra range.

Just some thoughts.
bc

[burglebox]

I'm fairly certain you need the gear reduction to increase the torque of the motor. You can get by with a "weaker" motor by allowing it to run at higher RPMs. The same thing applies to gas engines; they spin at thousands of RPMs only to be reduced and have their torque increased by the transmission.

Also, with DC motors at least, operating them at high voltage well below their RPM rating can cause them to burn out.

[BigTurd]

My thinking is, the existing rear end gear ratio is probably 3.4 : 1.
He might throw in a small gear reduction box if not already on the motor.
A gear reduction box is much smaller & lighter than a transmission.
This might provide all the gearing to keep the motor in its torque range?

I would like to create a diesel / electric like trains use.
Who knows...Might work in a car?

[bennelson]

It's a front-wheel-drive car, so there is no "rear-end" gear ratio per-se. I typically drive the car in 3rd gear, as though it were an automatic.

You are quite correct in that a gear reduction box would work well. The Solectria Force was a factory-built Geo Metro with an AC motor and a gear reduction box. They worked quite well and did freeway speeds. The Tesla roadster also uses a dedicated gear reduction.

In this case, is it worth it to do all the work to figure out what the correct gear reduction box is, fab mounts to connect it to the car, and pay all the money for the part, when the existing transmission works fine? I spent about $1300 for the entire project. I tried looking up a for sale gearbox from a Solectria and wasn't able to find any. At least the Geo Metro is a vehicle that somebody else has already designed a dedicated gear box for.

Ever lifted a Geo Metro transmission? It's not that big or heavy. I don't think there would be a lot of weight or space advantage to switching to a dedicated gear box. I have also heard of guys locking their transmissions in a single gear and removing the unused gears to save a little weight.

[manish par]

hello i am from india and i have a design of car and want to make it and thinking of making and electric car and can u suggest me how to make a car of our own design pls. thanx

[ride on toy dude]

i got hold of and old manual transmission, five speed lawn tractor. my dad was using the seized motor as a prop in a film and i decided to make it electric. now to my question. would you think that an 18 volt drill would be enough to at least make it go forward?

[bennelson]

A drill will be enough to make it go forward only if the tractor isn't carrying you or any batteries. Small motors like that have a lot of torque, but not long battery life, and the motor will quickly overheat.

You need a larger motor that can handle the continuous amperage required to ride the tractor around and mow the lawn.

My friend converted a gas riding lawn mower to an electric one. You can read about it at:
http://ecorenovator.org/forum/lawn-garden/161-ecorider-riding-lawn-mower-electric-conversion.html

[ride on toy dude]

i wasnt going to use it as a mower but instead completely remove anything related to mowing from the machine. hopefully that should shave 30 lbs from the thing. i want to use it as a transportation device. i also wanted to learn how to drive a manual on it since it is a 5 speed manual.

[ride on toy dude]

thanks!! i read his posts. would a starter motor work? i have one of those. it is easily twice the size of a drills motor.

[bennelson]

You don't want to use starter motors. They are only designed to run on 12V and only very briefly. You could use one of those on something like a light electric bicycle.

People have built drill-powered bicycles too. Just make sure to do the hard work of pedaling to get getting, then use the drill for cruising speed.

[ride on toy dude]

thanks so much. ill avoid using one of those.
oh, and my first ible was a drill powered bicycle.
i have also done the same with a razor scooter.
they were both friction drive.

[bennelson]

Cool, so that means you already know all the basics. You just need a larger motor and batteries for larger projects!

[ride on toy dude]

i would like to use a 130 horsepower engine in an old fiat spider. would that be enough to go on the highway? it would obviosly be my first car

[bennelson]

You are unlikely to find a 130 HP electric motor that will FIT inside a car!

Horsepower is often over-rated. While mainstream gasoline cars advertise what huge engines they have, you really don't need all that much just to cruise around a the highway. My friend has a 25 HP electric motor in his Dodge Neon, and it does highway speeds just fine.

Electric motors can also briefly produce considerably higher horsepower than their rating plate (which tells continuous power), whereas gasoline engines are rated at very high RPM.

[ride on toy dude]

so basically you dont need lots of horsepower, just lots of rpm so that the tranny can convert it to torgue

[bennelson]

Er, not quite.

It's that horsepower is rated very differently on an electric motor than a gasoline engine.

Horsepower is RPM times torque (oooomf x speed)

Most of the time in a car, you DON'T need horsepower, you need either Torque OR Speed. Most DC electric motors have extremely good torque at low speeds. The torque does drop off at higher speeds though.

But because you need torque at the low end to accelerate from a stop (but not much speed) and when you want to go fast, you need speed (but not much torque, unless you want to pass, my car does not have good passing power)

It's more that an electric motor has more appropriate characteristics for propelling a vehicle than anything.

[ride on toy dude]

Sweet! Thanks so much for the advice.
Oh, and how much did your conversion cost?

[bennelson]

The entire project was right around $1300, making use of plenty of salvaged materials.

More typical electric car projects can cost $5,000 to $20,000, but creative people don't need to pay those types of prices!

[jkelbach]

I'm interested in starting the project myself, would a 48v motor work from a forklift? also say i do have the budget for lithium ion batteries were could i locate these batteries and what wattage would i prefer?

[bennelson]

A 48V forklift motor would work fine! It will be wider than a DC permanent magnet motor, but have lots of torque!

I recommend that you order parts (including lithium batteries) from a reputable Electric Vehicle dealer. A good list to start with is provided by the Electric Auto Association at their "EV For Sale" page. Look under the heading "EV Converters, repairs, & kit or component suppliers" for companies that sell parts, including batteries.

The Electric Auto Association is a great organization. When you become a member, it includes a subscription to their monthly magazine, CURRENT EVENTS, which has great articles, news, and even the ads are worth reading for what the latest in products out there is.

[gunguru1]

Just finished reading this great project! This has given me some really good ideas... I have an old beat up VW Fox. Its like a diesel VW pick-up with a rabbit or jetta front end. I doubt the engine will ever run again and was thinking how much more room for batteries could .........maybe add a little more range to it!!! I have programmed a lot of DC motor controllers in the past and think with a little research I could write some great acceleration ramps that could make it more efficient!! Also, I was wondering how the braking works? Is the controller programmed for a coast to stop function or does it ramp down? Ramping down could actually be sucking a lot of useless power. In some of the more modern AC controllers you can change the frequency and voltage and force the motors to go faster than line frequency (60hz) will push it! I have not tackled anything quite so big but, I did finish a 48v self powered bicycle trailer..... Anyway, nice job!! Nice to see someone using their head!!

[jpayton]

Also does the electric motor produce any heat? Could you pump a little coolent through it then through the heater core?

[bennelson]

No, the motor doesn't get hot.

[jpayton]

I am trying to do this same project. One thing I was looking at was generating power. I know running an alternator only adds load. but what if you attached a alternator to the motor and hooked that output through a switch that was closed when you let off the gas. It wouldent add much resistance when its not generating and it would add braking force while generating power. My commute has a lot of hills. running 1 or more alternators down the hills would add a bit of power. What do you think?

[wobbler]

You don't actually need to add an alternator to do what you are talking about.

A motor being turned also acts a a dynamo/generator when no power is applied. In regenerative braking, this generated power is fed back into the batteries to get more mpw (miles per watt).

Look up "regenerative braking"
http://en.wikipedia.org/wiki/Regenerative_brake

There is also more information here, although it confusingly talks about "reversing the motor" and "the motor running backwards". This doesn't mean you need to physically reverse the motor direction in a car, but you use the back generated emf/voltage to charge the batteries using appropriate circuitry:
http://auto.howstuffworks.com/auto-parts/brakes/brake-types/regenerative-braking.htm

< to the article author: great effort and design! >

[bennelson]

Yes! That's one of the few ways you could get an alternator to work for charging an electric car. Still, you need that alternator to output your battery pack voltage, NOT just 12V.

Also, I would rig up the alternator to activate when you press the brake, NOT when you let off the accelerator. (Could could have the brake light wire connect to a relay that activates the alternator for example.) There are LOTS of times in my car that I am driving, but not touching the accelerator. My car seems to enjoy coasting.

[Mirio46x]

Hi Mr. Bennelson,
i read your article about converting Geo Metro to electric car , i was really thrilled.:) It looks very easy :)
I decide to convert some old car to electric car to get to work and back. I have few questions, which i need to answer, if you could help me:

- What car should i pick? Do i have to watch some special parts of car (transmition) I was thinking about Mitsubisti Colt 1996 or Peugeot 206 1998, what you mean?
- Why do you use exactly forklift electric engine?
- Can you tell me what power (kW) and torgue (NM) should the electric engine need to have?

My idea about the electric car is:
Day distance/range: 70-80km
Max. Speed: 80-90 km/h for 10km, and rest 50-70km/h.

Thank you for help.
Miro (mirio46x), Slovakia (Europe).

[bennelson]

These are some of the more common questions I am frequently asked. Please visit The Frequently Asked Questions section of my Blog. http://300mpg.org/projects/electro-metro/faqs/

[Mirio46x]

I cant move forward without the information about KW of your electro engine from forklift. Probably in our country, forklift use only gas, diesel engines.

[bennelson]

My motor did NOT have a power rating on it when I got it. I roughly based the power that it would be able to provide on its size, weight, and type of motor it is. Roughly, it is 10 inch diameter, 12 inches long, and over 100 pounds.
You could also do a search for Advanced DC or Netgain brand motors, as those are typical commercial motors available for electric cars. They will list motor specifics, including power.

[Mirio46x]

Ok, i will try it that way. ..
but could Tom G. (Dodge Neon) tell me the power of electric motor required for EV ?
Could you ask him or give me a contact to him?

Tx
M.

[bennelson]

The power required for a vehicle depends on its weight, aerodynamics, and speed you want to travel.

You can calculate those number using tools such as the ones at:
http://ecomodder.com/forum/tool-aero-rolling-resistance.php
and
http://www.evconvert.com/tools/evcalc/

Once you know those numbers you can look for an appropriate motor for your project.

[Mirio46x]

Thanks, i read your FAQ, but i am still bit lost. Maybe because of US units of measurement compare to ours. Also online calculators are pretty complicated for me.
Could you give me infos about your forklift engine (kW, RPM, Hz, kg) used in Geo Metro EV just for comparison, my conception.
If it is too private, please send me to private message.

Thank you
M

[WhiteTech]

I'm not sure if he has them in the first place, is what he's saying. So he doesn't know them,

[Mirio46x]

Sure, i dont have that infos, and ben too. And also i dont have infos about car aerodynamics.. it looks to be more dificult to calculate before even start with this project.