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:
and 300MPG.org

The primary "build blog" for this project is at:
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 instructional Video 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!

Step 2: Remove Anything Gasoline Related

Remove anything related to the gasoline internal combustion system.

That means that you are going to take off:
Gas tank
Exhaust, muffler, cat
Coolant tank
Fuel lines and filter

and anything else you can think of.

Removing all the extra bits saves weight and cleans up the car, making it easier to paint, run wiring, and do everything else in the conversion.

If you remove parts carefully, you can sell them to help cover the cost of the conversion. I bought the car for $500, but then sold the engine, gas tank, and radiator for $550. Free car to convert!

Make sure to not alter any safety gear. In this case, I was careful to make sure the driver and passenger airbags remain intact and functioning.

Here I am removing the gas tank. I had never removed a gas tank before, and couldn't figure a good way to drain it. What a mess!

Here's a video of me literally lifting out the engine with a pulley and clothes line! Hard to answer my phone with my hands full like that!

Step 3: Adapter Plate

You did make sure to keep the transmission, right?

We will use the car's original transmission as a way to connect power from the electric motor to the car's wheels.

The trick here is how to attach the motor to the transmission?

We will make an "adapter plate" out of a chunk of plate aluminum which has holes in it to line up with both the transmission and the end of the motor.

I pulled the transmission out of the car, and flopped it on some tagboard, then outlined it in pencil and marked all the holes.

I then took that and the motor end cap to a local machinist who is also a hot-rodder and knows way more about cars than I do.

He cut an aluminum plate to the size and shape required, complete with carefully aligned holes. The center of the motor drive shaft and the center of the transmission driven shaft need to line up perfectly.

Before bolting the motor and transmission together with the adapter plate, we need to design a coupler that will mechanically connect both drive-shafts.

Step 4: Coupler

The coupler is a means of connecting the rotary power of the electric motor to the transmission to power the car.

While there are a number of ways to do this, including keeping the clutch and machining the flywheel, I chose to keep it simple and use a "Lovejoy"-style connector.

Lovejoy connectors have three fingers and a shaft-hole. Put one connector on either shaft, and a rubber "spider" between the two. Poof! you have a mechanical connection!

Lovejoy couplers are designed with a keyway and set-screw, but both the shafts on this project are splined! Splines are much stronger than keys, but much more difficult to machine!

For the transmission, I took the old (broken) clutch plate and ground off the rivets to get just the middle splined center out. The machinist cut off the ears, lathed a step in the Lovejoy coupler, pushed the clutch spline in there, and welded it in place.

The motor spline COULD have been more of a challenge, as I didn't have any part with a spline on it for the shaft to go to. Fortunately, the motor was double-shafted (one on each end) and the back end went to a drum brake, which was the parking brake on the forklift.

I took the drum brake apart, sure enough, it was the same spines on the back end. I was able to get the very center, splined section, of the brake out, and use it to make the motor half of the coupler.

Line up the motor and transmission, with the coupler halves between them (with the spider in there) and bolt both the the adapter plate.

Congratulations! You have an electric car drivetrain!!!


I ran the car all summer with this set-up, but a few weeks back, it failed. I don't think the issue was the style of coupler. I think the main issue was that I installed the transmission and motor in the car seperate from each other. Because of that, I never got a true center alignment and bench test.

I rebuilt the coupler (with a little help from some friends - OK, I would have been lost without them..) by welding both female splines to a piece of flat steel plate, rounding it off, and adding a tubular jacket.

Then, the new coupler, motor, and transmission were all mounted to each other, tested, centered, and tightened. THEN the whole thing got put it the car.

Been working great since then.

Watch the video - it will make sense.

The first three photos at the bottom are the original "Lovejoy" coupler. The last two photos are of the current one-piece "solid" coupler.

Step 5: Motor

What's an electric car without a big electric motor to run it!?

I bought my motor for $50 out of some guy's garage. He had bought a junky forklift to build his own automotive lift, and had no use the the motor and some other parts.

The motor was very rusty and greasy, but it did spin (not fast or easily) when I applied 12 volts to it.

Rebuilding an electric motor is very easy. There are only a handful of parts to it.
I degreased it, removed the coils and sprayed them with insulating epoxy, checked the bearings, put it back together, and painted it.

I also had the machinist put the rotor on his lathe and take a tiny bit off the commutator. That makes it looks new, and provides a smooth, conductive surface for the brushes to ride on.

I also replaced the brushes, purchasing new ones at a shop that specializes in forklift motors. $50 for the new brushes brings the total cost of $100 for a pretty decent electric motor.

Step 6: Batteries

The motor won't do you any good, unless you have some batteries to power it with.

This car uses 6 x 12V batteries, for a 72V system.

These are Deka Dominator true Gel-Cell batteries. They can not leak or spill acid, nor do they require watering.

I was fortunate enough to be able to get these batteries, slightly used, for $12 each - essentially scrap metal prices!

One downside of these batteries is that they are picky about charging voltage. I was finally able to find a 72V charger designed for these batteries, and got it used for $200.

If I had used the more typical deep-cycle flooded batteries, I could have used a different charger, or even 6 12V chargers, one on each battery.

Four batteries are in the cargo compartment of the car, and two are in front, where the radiator used to be.

For the rear batteries, I cut two pieces of bed frame to lay across the spare tire well, and ran a bolt through the end of each piece down into the frame of the car.

For the front batteries, a few friends came over and helped me weld in a metal tray for the two batteries to sit on. Then I cut two short pieces of unistrut, and ran threaded rod through holes in the tray to bolt the batteries down. I then insulated the front batteries with rigid styrofoam and re-installed the front bumper.

I went to the boat store and bought a "battery charger power inlet". This is a male electrical connection with a rubber cover. Since the gas tank was already removed, I installed the power inlet where the gasoline used to go in.

I added an additional circuit in my garage, just for the car, and have a 25' 12 gauge yellow extension cord with power indicator light in the end, just for plugging the car in with.

Plug it in at night, and it's charged the next morning, automatically.

Update! I later played around with more batteries. With a motor controller that supports higher voltage, I was able to run up to 144V (12x 12V batteries.) At that voltage, the top speed of the car was at least 73 mph, but I really had no cargo space.
Just so you know, Ford Ranger front coil springs fit the back of a Geo Metro, but you have to shorten them.

Step 7: Controller

The controller is an important part of the electric car conversion.

The controller is a solid-state electronic box that controls the power (speed) between the batteries and the motor.

My controller is a Curtis 400 amp peak PWM controller designed for use with series-wound motors. It can run on 48-72 volts.

The higher amperage your controller is, the better your acceleration will be. The higher voltage, the better top speed and efficiency of the car.

Also, keep in mind that amperage is also what defines range in a battery. Capacity is marked in Amp Hours, but draining a battery at double the amps will give you LESS than half the run time! Having a controller running higher voltage will use LESS amps to do the same amount of work.

What's this mean? Buy the highest voltage controller you can afford! 48 volt controllers are cheap, as they are used in so many golf carts. 100V+ controllers get expensive real fast.

My 72V controller seemed to be a good compromise of cost and efficiency. I bought it slightly used on E-Bay for $300.

Follow the schematics available through the controller manufacturer to connect the batteries to the controller and motor with heavy gauge cabling, such as welding cable, with solid, heavy-duty lug terminals on the end.

The controller requires a 0-5Kohm potentiometer as a "throttle". This could be as simple as a $3 Radio Shack part, or as fancy as a purchased, specialty part such as a Curtis PB-6

I split the difference and installed a 0-5K pot inside a free-from-the-junkyard forklift throttle control.

Run the gas pedal cable to the potentiometer, so that when your foot is on the gas, it sends a variable signal to the controller.

Update! I later switched over to running an Open ReVolt motor controller. It's the same one you can find here on Instructables at https://www.instructables.com/id/Homemade-100-HP-Motor-Controller-for-an-Electric-C/
That controller is good for up to 144V and 500amps.

Step 8: Other

Currently, the car is insured and registered, although the DMV is still requiring that I drag it in and PROVE that there is no engine in the car before they give me the emissions tesing exemption.

This car can go for 20 miles on a charge, and has a top speed of 45 MPH, the speed limit right outside my house. In town is all 25 mph anyways. My typical ride is 10 miles for going to work, grocery store, post office, etc, and back home.

If I doubled up the battery pack, I should be able to go 30 to 40 miles on a charge.

This project has cost me about $1200 total, including buying the car in the first place. If I would have done the machining myself, I would have only spent around $800 for everything. This car charges at my house through a renewable energy program. All electricity comes from wind, bio-gas, and other renewable energy sources.

I kept the back seat and can carry four people total.

The original driver and passenger airbags are completely intact and functional.

I mostly drive this car in third gear. Turn the car on - put it in third - drive. It's really that easy. There's no engine to kill, so you don't have to push in the clutch before coming to a stop. The motor has so much torque that I can pull away from a dead stop in fourth gear.

I still need to come up with a heater. (EDIT: Please see below) I think I will wear an extra thick coat and gloves for winter driving and have an electric defroster on the dashboard to keep it from frosting. The heat issue has been on my mind since the start of this project. The inefficiency of a gasoline engine is a blessing in a cold Wisconsin winter.

I did gloss over a few steps of this project.
I skipped telling you how many times I took apart, and put back together, the electric motor. How many times I lugged it back and forth to the machinist's. A friend and I were up til 2 in the morning one night fixing the control arm mount! Or how I had to literally shorten the motor because it was too long to fit in the car! But those things are for another story at another time!

I made sure to have an interlock, so I can't accidently drive away while plugged in. Make sure to have a nice big fuse inline of your main battery pack.

All the little challenges of a conversion like this are part of what makes it fun and interesting. In my case, I did a fair bit of experimenting of the best way to run the power brakes.

Winter Heat:
Sure, gasoline engines aren't efficient, but all that waste heat sure is nice in the winter. Since this car no longer has the original engine, it doesn't have the original heat either. The blower motor is still there and works fine for defogging the windshield.
Some EV converters remove the original heater core and replace it with a ceramic heating element that runs on their pack voltage. That sounded like a lot of work, and I was already sick of tearing apart the dashboard.

I already had a household (120V AC) electric oil-filled radiator. I just put that behind the passenger seat, and run an extension cord out the window to a timer.
The heat comes on automatically in the morning and heats up the inside of the entire car before I get in it.
The mass of the oil in the radiator stays hot for about 10 minutes or so after I leave. Most of my trips aren't any longer than that anyways.

I like that with this heat system in that:
1) I didn't have to buy a darn thing
2) The entire interior of the car is already warm - seats, steering wheel, everything!
3) This also helps keep the batteries warm.
4) All the electric power comes from the wall, instead of the batteries

The only down side is that if I am parked all day somewhere that I can't plug in, I don't have that same heat for the ride home. On the other hand, most of my trips are pretty short, so it's not the end of the world.

This heat system consumes about 5 cents worth of electricity per use.

One of the reasons why I chose this car to convert was that it has manual windows, manual locks, manual transmission, non-powered steering,pretty much manual everything - except the brakes. The first time I drove the car as an electric conversion, I found the brakes to be a little hard. (You CAN stop the car WITHOUT power brakes, you just have to push really hard!) It was just a low-speed test drive, but it was pretty obvious that I had to work on the brake system. Power brakes work on vacuum created by the engine. Without an engine to make the vacuum, the brakes just don't work the way they should. 
Some people say to find a different, manual, master brake cylinder and install that, or even just to punch a hole in a certain spot in the cylinder to convert it to manual. Neither of these sounded like great options. Really, I just needed an electric way to make a vacuum.
So, to start out with, I played around with an aquarium air pump, just to learn how the vacuum brake system works. After that, I starting looking around for a 12v air pump with a connection on the "In" end, so that it could be used as a vacuum pump. A friend of mine dug one up, along with an aluminum bottle that had a threaded connector already on it.
I connected the air pump to 12V+ power through a vacuum switch. The vacuum switch measures vacuum in the bottle - if there isn't enough vacuum, the switch turns on the pump.

Now the car has power brakes, just like it did originally, only it's driven by a tiny electric motor in a little pump, instead of by a gasoline engine. Compare this to newer versions of the Prius, where the air conditioning is driven by an electric motor. That way, you can have AC without the engine running!

Step 9: Now You Make One!

An electric car really is fun to drive!

My house is on a renewable power program, where I get all my electricity over the power lines, but coming from bio-gas, wind turbines, and other renewable energy sources.

Doing a calculation on energy consumption, comparing gasoline and electricity, the car gets the equivelent of about 130 miles per gallon

This has been a fun project to work on and I have learned tons doing it. Keep in mind that I have NO background in electronics or engineering. All I did was go to the library, start talking to people, and learn what I could!

If I can do this, so can you!

So how about it? Are you building an electric car or have any other DIY Green Tech? Let me know!

You can stop by 300MPG.org to see the videos that my friends and I are making to teach you, step by step, how to build your own electric car!

I found that there was a lack of instructional videos in the world of electric cars. I bought a couple, and they all were TERRIBLE! So, I made my own! Stop by 300MPG.org to check it out!

Take care, and keep it green.



PS: if you enjoy the videos, please give them a high rating, this helps me to be able to keep making them!

For more photos of this project:
<p>Can't get the gallery.me.com links to open. I'm trying to figure out how much space was actually consumed by the batteries (E.G. how you fit them all in there) since I'm looking at building a custom L-Ion pack (or more if needed).</p>
why try and build some type of altenator that way while u drive it can charge batteries and drive unlimited
<p>because you would be breaking the first two laws of thermodynamics which make doing that impossible</p>
It is not impossible.
<p>It's possible to build, but it wouldn't work so why bother?</p>
<p>To generate electricity you need power, as in a power station with hydro, coal or solar power going in, and this power in converted ( not made ) into electricity. A generator with a 1 horse power gas engine can output a bit less than 1 horse power of electric power. If you use the cars electric motor to run a generator/ alternator you use as much power ( little bit more actually) as you convert, so no extra energy is made. Any power used to generate electricity is not available to power the car.</p>
<p>you are changing part of the rotational energy from the axle into electrical energy</p>
<p>a kers system would be excellent on a setup like this, get back some of that power wasted stopping after all that's supposed to be the general purpose of electric vehicles Is efficiency</p>
<p>How do you change gears without a clutch?</p>
<p>It's surprisingly easy. Just rev the motor up to the right speed, and push it into gear. It took about a day to get used to for me.</p>
<p>MPaulHolmes, does changing the gears in this way not damage the gears? I'm asking, not to be critical, but because I am hoping to build my own EV. I'm wondering whether I need to try to keep the clutch. It seems like most people don't use a clutch, but to me, that sounds like it would damage the transmission pretty quickly.</p>
<p>when the gearbox gear driven by the motor ( the motor side gear ) and the gear on the wheel side are turning at a matching speed they will engage smoothly, If the gears are not turning at matching speed then they will grind when trying to engage. With no clutch you use the motor (electric or gas ) to adjust the motor side gear to match the speed of the gear to engage. With a clutch the motor side gear will free-wheel, is very light and in synchromesh 'boxs is adjusted to matching speed by the synchromesh system ( small friction clutch on gear ). In a dog box ( no synchromesh ) you need to match speeds by waiting for the gear to slow or reving the engine with the clutch engaged. </p>
<p>That's how most truck drivers do it...</p>
<p>Automotive transmissions aren't made the same way truck transmissions are. Truckers don't shift like that right off the get go, either. Takes some time of learning the truck and how it shifts by shifting properly. I'll be doing this conversion to a 2009 Base model standard jeep compass, and I'll for sure be keeping the clutch. I guess It'll be easier to maybe take out the clutch? But for longevity, keeping the clutch is the smartest way to do it. <u>In my own opinion!!!</u></p><p>More fun that way as well.</p>
<p>an electric motor doesn't spin if you're off the throttle, and there's no flywheel to worry about, so the clutch isn't necessary.</p>
<p>If I wanted to build a sports car, would I need to make my own custom motors or buy different ones? Also, in most electric cars, does the motor transfer motion through a transmission... I thought they were connected directly to the wheel and the voltage was controlled to change speed.</p>
<p>and is there any way to make the battery last longer? Would a battery salvaged from a prius for example give longer runs. I know to get a car to run as long as a tesla would be very expensive but maybe around 100 miles per charge would work with a few solar panels on top to make that even more?</p>
<p>a prius battery is no different than a regular car battery. ideally you would use marine deep cycle batteries. for more life you can also just use another battery bank hooked up in parallel to the existing battery bank.</p>
<p>This is a great project. Awesome.</p><p>I would like to ask, how long can the electric motor keep running on a single charge? I saw you mentioned that the max distance was 20 miles at 45 MPH, is it about 27 minutes? </p>
Can I use 3 phase ac motor without amp regulator just with ac-dc inverter and frequency inverter?
Does the gas engine need to run?
Also what was the total cost
<p>Electric cars are gaining more exposure in the mainstream market of various states due to the proven environmentally-friendly and costs-saving features that the whole idea has got to offer. If you are able to build one of your own in your own backyard, it would only mean more savings for you!</p>
<p>Could you please tell us the total kWh of the 6 batteries you used? Thanks!</p>
<p>Would a couple of these forklift motors be enough to make a hybrid drive like on a locomotive? I'm fabricating most of the truck, I just don't know much about electric engines. I also have access to a 40&quot; 3 phase but it weighs like 1300 pounds. It's for a rather large vehicle. It'll have two large generators, so I'm not too worried about batteries. I can control acceleration with the rpm of the generators.</p>
Through my scrolling I haven't been able to discover the voltage of the motor you rebuilt.
I'm sorry I just saw how much it cost :) you're amazing!!! :)
Hi :) how much did your conversion cost in total?
<p>This is great! I have a little 1995 Ford Aspire, automatic transmission but manual everything else, with medium mileage (80,000). The plan was to run the little bugger into the ground while saving up for a Leaf...but converting it in advance of that (and selling the engine!) sounds much more appealing. Does this process work with an automatic transmission? And 90s Aspires are basically Geos, right?</p>
<p>Are these the regular lead acid batteries we have in cars to start the engine, lights etc?</p>
<p>Hello</p><p>I want my production Electric Car</p><p>But I do not know where is the best engine and the best battery</p><p>Where To Buy</p><p>Please tell me</p>
<p>Who is your insurance provider? I have spoke with 3 so far and they all wont insure a car with a BOM.</p>
<p>You are my hero ! ;-D<br>I will build my own electric car :-D</p>
<p>This project is so advanced but yet does not look that complicated after all. However, I think you would still require a tyre and rim insurance after being done with the conversion job. This is just to help safeguard yourself against any possible unfortunate events that might follow you in your DIY masterpiece.</p>
<p>but does'nt the motor overheat</p>
<p>but does'nt the motor overheat</p>
<p>but does'nt the motor overheat</p>
Awesome sauce!
I thought that transmissions were only for gasoline cars. Why did you have to put one on an electric car's motor?
<p>Most motorized things require some form of a tranmission, electric, diesel, propane, and gasoline engines all typically do dependin on application. They do so for two reasons, one in earlier rwd cars the crankshaft of the engien couldn't directly be hooked up to the wheels, so a gearbox drive shaft, and rear differencial are needed, to change the direction of the power output. Secondly and more importantly, without a transmission of some form the engine would always be engaged to the wheels, meaning the second you start it up, even while idling it will be moving, constantly moving, and with such a setup the brakes would be fighting the motor all the time making for horrible stopping power and great potential of either a damaged motor or failed brake system, the clutch/torque converter allows them to disengage from eachother, allowing you to stop.</p>
<p>Mate that was awesome well done something to be proud of :-)</p><p>One thing is I was wondering to save battery power would there be an advantage installing a light flywheel to install the clutch so you can change gears?</p><p>I know electric motorcycles benefit greatly if they have a manual gearbox.</p><p>It requires a lot less power to take off and maybe a smaller motor could be used.</p><p>It would not be that hard to do.</p><p>Regards Rik</p><p>Home Mechanics</p>
<p>This is a great project, thumbs up..I have 2 points to raise: did u do the math how much $ u will save till batteries ascend to God ? the other thing is what about all those bloody sensors hooked all around the notorious combustion engine ? how to keep them quiet from making the computer stop the car ?...oh.. on a 2nd thought, what can the computer do ? cut the fire from plugs? or shut the carbeurator ? they re kicked out of the car anyhow..still some sensors that bring signals to dash may need to modify.</p>
<p>For someone who claims to have a low level of knowledge about cars I salute your ability to soldier on in any case. I am a mechanic and looking at your project for the hints on how to go about the conversion. LOL</p>
Why did you put a trans. To the motor, i thought that transmissionswere only for gasoline cars, why?
Ever put a solar panel on electric car????
<p>hello</p><p>i wanted to now more about it </p><p>i like elec car wil you help me</p><p>greetings sam</p>
<p>Hi guys,</p><p>you are the pioneers of electric cars so I would like to invite you to join 80edays, the hardest EV endurance test driving around the world! </p><p>I would like to make a link exchange with this great website.</p><p>Kind regards</p><p>Rafael de Mestre</p><p><a href="http://www.80edays.com" rel="nofollow">www.80edays.com</a></p>
<p>Hi Ben! The ecomodder and 300mpg links aren't working.</p>

About This Instructable




Bio: Ordinary guy with no special skills, just trying to change the world one backyard invention at a time. See more at: http://300mpg.org/ On ... More »
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