FAQs

Frequently asked questions about my homebuilt electric car project.
I get plenty of questions through YouTube, web forums, and other places asking specific questions about my car project. However, since many of them seem to be the same questions over and over, I am simply going to start a compilation of questions and answers right here to help everyone out.

QUESTON:
What is the top speed?

Answer: On a DC motor system, speed is primarily based on VOLTAGE, which is mostly based on how many batteries you have hooked in a row (series connection.) The speed limit right outside my house is 45mph. In town, where I can find the bank, grocery store, library, etc., it’s all 25mph. So, I designed the car to go 45mph. This car, with a 72V battery pack will do the speed limit where I drive. I decided that I do not need to go interstate speeds to get to the grocery store. With more batteries in series, the car has a higher top speed. At 144V, the car can go over 70mph.
I have gotten a speeding ticket in this car.

QUESTION:
Can the car easily cruise at 55mph for a range of 50 miles?

ANSWER:
No. It was never designed to.
RANGE of an electric car is largely dependent on the CAPACITY of the battery pack, measured in Amp-Hours. The more bigger battery pack, the farther you can go. At some point, you just don’t have the room or weight-carrying ability to put more batteries in a car. In addition, the HEAVIER a car is, the more energy it takes to travel the same distance (you could say it gets worse fuel-economy.)

This car typically runs on six 12V batteries, each rated at 100AH. The math of multiplying all those together makes 7,200 watt-hours, or 7.2KWh. This car uses about 300 watt-hours per mile of travel. Dividing 7200 by 300 gets 24. 24 miles is the maximum theoretical distance that the car should be able to travel when fully using the batteries, all the way down to zero. Of course the batteries aren’t going to like that. Try using a number of half that (50% of battery discharge) to keep the batteries happy and long-lived. In this case, that’s only 12 miles, which doesn’t sound like much. However, my average trip to the library, grocery store, bank, hardware store, and post office, and back is just under 10 miles.

If I wanted to add more batteries to the car, there’s not much stopping me. As it is, the inside of the car looks pretty stock. I have a “normal” backseat and trunk. Adding more batteries might start cutting into my cargo space. I already have the range to go to the grocery store and back, AND I have the trunk space for groceries! It’s a win for me. That said, I would like to try to fit a few more batteries under the hood. That will give me a better range and top speed, without and real change to the rest of the car.

Some lead-acid battery cars can go 50 miles on a charge, but that’s on the high end. My car is definately on the minimal end. All of the major manufactured electric cars coming have some form of Lithium batteries. These batteries are smaller, lighter, and more expensive. Cars like the Leaf can go up to 100 miles on a charge. The Tesla Roadster can go over 200. It also cost more than my house. It’s very difficult to compare the performance of a $100,000+ carbon fiber sports car to a $1300 homebuilt economy car, but lets try…
The Tesla claims 240 miles percharge at a retail cost of  $109,000. (We’ll ignore sales tax, etc. on buying one of these.) A little math tells us that it comes to about $445 per mile of range to buy this car. On the Electro-Metro, the complete cost of building the project was very close to $1300. Lets go with the 12 miles range just to be really conservative. That’s about $108 per mile of range for this vehicle. So, in terms of just plain miles you can go versus cost, the Electro-Metro is four times as cost efficient as the Tesla. (Granted, the Tesla IS a MUCH cooler car!) Keep in mind that the Metro was also built with off-the-shelf parts, and could be made by just about ANYBODY. And again, adding more batteries is always an option.

QUESTION:
What do you think of installing solar panels on the roof?

ANSWER:
I think it’s a great idea to install solar panels on the roof….. of my garage.
Referring back to the batteries answer earlier, the car uses about 300 watt-hours per mile. That is the amount of electricity used if you had five 60-watt lightbulbs on for an hour. A solar panel to create 80 watts in full sun will be larger than 3 feet long and 2 feet wide. You will need 4 of them to make at least 300 watts, and they will never be faced properly into the sun. (Except parked in full sun on the equinox…) So let’s say you now have the car with something like a ladder rack to support all these solar panels (and only drive on windless days…), You still have to be parked in the sun for an HOUR for every MILE you want to drive. If you live someplace VERY sunny, and ONLY drive short distances, and infrequently, this may actually work. You will have  a very funny looking car, with the charging system that costs more than the vehicle, but it could work. You would also run into a problem in terms of WHEN you could charge the car. Lets say you go out for a drive in the evening. You can’t charge at night (no sun!) so charging doesn’t start until the next morning. Eight hours later, you now have enough charge to go 8 miles. And that’s only if it wasn’t cloudy that day.

A far better way to deal with all this is to put solar panels on the house, the garage, or mounted in the yard. Those panels can be bigger. You don’t have to worry about them getting ruined in a car accident. If they are grid-tied, you can sell extra power to your utility. At night, charge your electric car from the wall, at less expensive “off-peak” electric rates. It’s a win for everyone.

QUESTION:
How many batteries did you finally put in?

ANSWER:
Just six. (Seven if you are also including the original “accessory” battery, which runs the headlights, radio, etc.)
It’s enough to get me around with acceptable range and speed, while still keeping the full trunk and seating for four.
I am looking at adding some additional batteries under the hood for increased speed and range. This will require purchasing some batteries of a different size (just has to do with how they would fit) and some custom welding to build a rack to mount the batteries in.

I have experimentally run the car on up to 12 batteries. Boy was that fun! The car could go over 70 mph and do burnouts. The entire back of the car was full of batteries though!
I think that for the long run, a compromise of  a 96 or 108 volt system will be ideal for this vehicle.

QUESTION:
Can I use an X motor in my car? (Can I use a 32V motor? Can I use a 50lb motor? Can I use a 6″ diameter motor?)
ANSWER:
I can’t tell you. There is no way to know if a motor would be appropriate or not, just based on its rated voltage, or any other single property.
The rated voltage is almost one of the least considerations of the motor.
More important are what type (usually want a “series-wound”) and the physical size and construction.
A general rule of thumb is is to get a motor from 100-150lbs. Make sure you clean it up and that the brushes are good. Also, check the bearings.
By putting higher-than-rated-voltage through the motor, you increase the horsepower. Remember, it’s amperage that creates heat, not voltage, but amps x volts = power!
Most forklift motors are totally overbuilt and can handle more power than their ID plate says.
A motor somewhere between 6″ and 11″ in diameter will have enough power, but still fit in the vehicle. Also, larger motors deal with overheating easier, in that they have greater surface area and mass.
Make sure the length works for you too. In the Electro-Metro, I used a 36V rated forklift motor that is 10″ in diameter. The distance from the center of the driven shaft of the transmission to the passenger drive shaft (this is a front-wheel drive car) was only about 5.5 inches. This motor really is the biggest I could fit in the car. Any larger diameter, and there wouldn’t have been room to reinstall the passenger side half-shaft back into the transmission. Length matters as well. I had to cut the tailshaft off the motor or it would have rubbed on the passenger tire when making left turns!
For a nice discussion on the topic, please see:
The guy who started that thread is a professional motor man who has done some really cool work hot-rodding motors for electric vehicles.

QUESTION:
Why not just add an Alternator/Generator?

ANSWER:
Running an alternator from the motor to make electricity to recharge the batteries is a bit like trying to fly by pickup yourself up by your own belt. Try all you want, you won’t come out ahead. Even if we completely ignore the cost and complexity of connecting a high-voltage alternator to an electric motor, the big question is ENERGY INPUT. In a typical gasoline car, the external energy source is the gasoline, filled into your tank at the gas station. On an electric car, the outside energy is electricity from the wall outlet, through the charger, into the battery pack.

An alternator does not ADD any outside energy into the system. It’s only a way to change mechanical energy into electrical energy. It can only lose energy in the form of heat and noise. It can NOT create energy. It also does NOT make any more efficient use of the battery’s electric energy. That going basically straight from the batteries to the electric motor is about as efficient as you can get. Adding more steps to the process only LOWERS efficiency.

On the other hand, if you added a gasoline generator, that WOULD add an outside source of energy to the system, in the form of the gasoline in the generator’s fuel tank. However, you also add complexity, an engine, a carbuerator, air filter, oil filter, exhaust system, noise, etc, etc. And you don’t really have an electric car any more. Now you have some sort of a “Plug-In Hybrid”. Not that there is anything wrong with that. That’s exactly what the Chevy Volt is, and when I saw it, I have to say it’s a pretty nice car. But you really can’t call it an EV.
(There are all sorts of discussions on the web right now about exactly how to describe the Volt. I guess I would simply call it “unique”, as there is no other car out there right now that uses the exact same setup. Love it or hate it, it IS in a class of it’s own.)

I DID do an experiment with my car adding a propane generator from an RV. The generator has a 250CC engine and could provide about half the energy needed for the car to cruise down the road. It also took up all the cargo space, and was louder than I care for. After some test drives, I decided that a better way for additional range would be one of two extremes – either a bunch more batteries and no generator OR a much bigger generator, better integrated into the car (under the hood, reusing original exhaust system, etc.) So, that gets us back to the Nissan Leaf vs Chevy Volt styles of building a car.

For me, I like it simple and not having to change the oil….. EVER AGAIN.

To me, that’s just a plain motor and batteries.

Question: What’s the CAPACITY of the battery pack?

Answer:
The batteries are 100 AH, and I have typically been running with 6 of them.

12V x 100 = 1200WH x 6 = 7200.

So, it’s a 7.2KWh battery pack. However, it is all USED batteries, so I can’t expect them to perform like new.

300 Wh per mile is a common number to use as an estimate of how much energy a car like this uses. If you divide the number in half (because you only want to use half the battery pack, to keep them happy and give them a nice long life) that’s  3600 wh, divide that by watt-hours-per mile (estimated 300) and you get 12.

So, this car, running on only 6 used batteries, can regularly 12 miles per trip. That doesn’t sound like a lot, but I live 2 miles from town, 2.5 miles from the grocery, 3 miles from the hardware store. You get the point. My typical trip of running all my errands is about 10 miles. And that’s running the pack half-way down. If I want to take them down to about 80% discharge, that’s a nearly 20 mile range.

6 12-volt batteries is really bare minimum for an electric car. Recently, I removed one of the used batteries and added 4 new Die-Hard Platinum batteries. The car has much more ooomf! and better hill-climbing. (There’s two LARGE hills in my area)

 

Question: What car should I pick for my conversion?

Pick a car you like. If you don’t like it as a gas car, you won’t like it as an electric car. Make sure the body is sound. Don’t convert a rusty car. No sense putting in all that work only to have a rusty car when you are all done. On unibody passenger cars, the body is also holding the weight of the batteries. In general, you want a car with a manual transmission. Automatic transmissions can be converted, but are more complicated, more work, and yet less efficient. Pick a car that has enough cargo space and weight-carrying capabilities for the number of batteries you want. Station wagons and light trucks are popular.

 

Why did you use a forklift motor?

It was cheap and it works well. A series-wound electric forklift motor is powerful, very similar to what is sold commercially just for electric cars, and was very affordable. A used forklift motor can be found at a junk yard or other places (I found mine at a garage sale for $50!) It only really requires basic knowledge of electric motors to examine the motor, clean it up, inspect the bearings, and replace the brushes.

 

Can you tell me what power of motor I need for my project?

No, but you can figure it out. There are a number of on-line calculators that will assist you in figuring out speed, power, and other things about your project before you buy any parts. The EV CALCULATOR will help you figure out range and speed of your EV by entering what car, what batteries, etc. Over at EcoModder.com, they have a nice tool to figure out energy use of your car at various speeds.

 

Question: I want my car to go XX MPH/KPH for a distance of XX miles/km. How do I do that?

Using the tools listed just above, you should be able to ball-park your vehicle’s top speed and range. Please have realistic expectations. Remember that it takes MORE than twice as much energy to drive 75mph as it does to go 45mph. After you do the calculations, do a bit of a reality check. Can that many batteries physically FIT in a car? Can the car carry the weight of the batteries? Lead-acid batteries have diminishing returns when it comes to weight, space, and range. Lithium batteries are considerably better, but greatly increase the cost. Do your research to make sure you know what you are expecting before spending money on batteries and either spend too much on Lithium or are disappointed in the range on Lead.

 

Question: I’ve got a Geo Metro! Can you convert it to electric for me? 

No, but I’d love to see you do it. I put a lot of time, energy, blood, sweat, and tears into my project. It was great fun and a fantastic learning experience. I did take time. For me, it was about 6 months. Of course I could do one faster now, but to charge somebody to convert a car for them, it would either cost them too much or I wouldn’t be able to make enough profit to make it worth my time. Instead, I strongly encourage you to purchase the BUILD YOUR OWN ELECTRIC CAR: CHEAP! instructional DVD set. In it, I take you through every step of converting my car from gas to electric.

Got more questions? Ask them in the comment space below! I’ll answer them, so everyone can benefit from learning more about this project!

{ 22 comments… read them below or add one }

1 Ryan March 20, 2011 at 11:27 am

How much do the batteries cost?

2 admin March 20, 2011 at 4:20 pm

Batteries, like anything else, run a range of prices. It depends on where you are, what size, what chemistry, what capacity the batteries are.
My batteries I bought used for $12 each. The batteries in my electric motorcycle, I paid $200 each, new.

In a typical conversion, the batteries are one of the major cost factors. Expect to pay several thousand dollars for a large pack of new batteries. A little bit of searching around for the best deal can end up saving you money.

3 Mark Miller April 19, 2011 at 11:55 am

Ben,
I am fascinated by your project! So, do the gears grind when you put it into gear? Is it front wheel drive? Just wondering. I really, really want to build one, but I’m not so sure that my wife would like me to spend any extra money right now.
Please reply.
Thanks,
Mark

4 admin April 19, 2011 at 12:22 pm

Hi Mark,
No, the gears don’t grind, and yes, it happens to be a front-wheel-drive car.

When I put the car in gear, the motor isn’t yet spinning. (Unlike an engine, which would be idling.)
I mostly drive in 2nd and 3rd gear. To shift, the speed of the motor needs to be somewhere near an appropriate speed for the gear you are shifting into, but that’s it.

At stop signs an traffic lights, the motor just comes to a complete stop, so there is no need to shift to neutral or push a clutch.

If you are seriously considering a build, please consider ordering the video I made teaching others how to do a similar project.

5 Brian Dirrim November 22, 2011 at 9:43 pm

Ben,

Could you post the schematic of the whole electrical setup of your conversion. I know there are differences with other vehicles, but would like to see yours-I bought the DVD and watched your videos.

You did a good job and provided a great deal of information. I am becoming more confident in starting the project.

Thanks and keep up the good work!

6 admin November 23, 2011 at 9:57 am

I never really did any official schematic of my vehicle. It really is pretty straight-forward.
To connect the motor, batteries, and controller, there are a number of great schematics already out there. Alltrax’s “Document Depot” has a number of user manuals for their DC motor controllers. They all have nice schematics in them. That’s all I used for hooking up all the electrical in the car.

Other than that, I connected the keyed ignition switch to turn on the power to the motor controller and main contactor. The 12V car accessory battery just has a low power 12V charger permanently wired to it, and the connector for the main battery pack charger just goes to both ends of the battery pack.

It’s really all that simple.

7 Guy in MI November 26, 2011 at 2:24 pm

Did you explain somewhere how you powered the 12v system, i.e., radio and headlights, etc?

I’ve read that a high voltage to low voltage DC to DC converter can cost multiple thousands of dollars. A basic alternator costs $50 to $100. As your FAQ points out, they aren’t efficient, but they are exceptionally cheap and an off-the-shelf component. A typical 45A alternator will draw 2Hp (~1492 Watts) and produce 1HP (~746 Watts). That’s plenty to power the 12V system. If the main motor is not run continuously, i.e., stopped intermittantly, the alternator’s field coil will have to be repowered. However, a simple circuit can do that, or you can just keep the main electric motor “idling”. Normally, the alternator is geared about 3:1, i.e., it’s spinning at 3600rpm while the ICE is at 1200rpm. It’ll have to be geared appropriately for working with the main electric motor. Since the 12V system is not starting an ICE, the CCA ability of a 12V automotive battery is not needed. A much smaller 12V battery can be used, perhaps a motorcycle battery, if needed to power things when the main motor is off, or prior to the main motor, or intermittantly. The battery can probably be eliminated. What are your thoughts?

8 admin November 26, 2011 at 3:18 pm

I kept it real simple.

I use the original 12V battery. That’s already hooked up to the headlights, radio, etc. It is electrically totally separate from the propulsion system. I have a small 12V charger that is permanently wired to the battery. When I plug the car in, that charger gets power and charges the 12V battery. You can’t get any simpler than that. It’s already there. Already paid for. Nothing has to be modified or moved around. I already had the 12V charger, which mounts directly on the side of the battery taking up next to no space.

The next step would be to raise the car’s system voltage to 120V or more. At that point, I can use an off-the-shelf or salvaged power supply to convert higher voltage DC down to 12+volts to act as a DC/DC converter to constantly top off the 12V car battery. It’s cheap, simple, and straight forward, but requires a bit higher voltage.

9 Guy in MI December 2, 2011 at 2:58 am

The 1HP (~746 Watts) a typical alternator outputs is usually at 13.8V or thereabouts. That’s higher than the battery voltage in order to charge it. All of the 12V DC power supplies I’m aware of are 12V, not 13.8V. E.g., 12V output of a PC power supply, 12V landscape lighting transformers, 12V laptop DC brick power supply, etc. Do you think the lower voltage will be an issue for charging? The typical alternator outputs 55A, not 45A I stated previously. I drove a car years ago that had a failing alternator. My lights and radio drained a large auto battery in about a half-hour. How depleted does your 12V system battery get? Is it deep cycle or normal auto? Do you recommend an stiffening capacitor on the 12V system? I.e., have you noticed temporary power drop-outs or brownouts with lights or radio? Do you recommend lower power consumption lights and radio? The new extra bright headlights seem to consume 10 times as many amps as OE lights.

10 Ben N December 2, 2011 at 8:40 am

There are plenty of “12V” power supplies that are actually a little higher voltage, or are adjustable. Here’s one that I got that can be adjusted up fairly high – I think this one could go to almost 15 volts. For use, I would have it adjusted to an appropriate voltage for 12V battery charging.

power supply

It’s rated for 15 amps, so it’s good for about 200 watts or so. That’s plenty enough for headlights and radio. I had only been using a standard car battery (not a deep cycle. It was free.) I generally only take short trips in the car, so headlights and radio are never really on for extended amounts of time. Still, a deep cycle battery would be better, and a battery being topped off by a power supply would be better yet.

Some power consumption can be controlled. There are many LED taillight bulbs now available. I haven’t seen any affordable, D.O.T.-legal LED aftermarket headlights, but we will eventually have them. My car uses the stock, original headlights, which work fine and aren’t particularly high draw. I also have an LED dome light in the car. One advantage that I have noticed is that as the car’s accessory battery gets drawn down, the LED light does NOT dim or change color, unlike conventional incandescent lights.

Other advantages of a power supply over an alternator:
Works continuously, whether or not the drive motor is spinning
Can be mounted nearly anywhere
An alternator must be mounted on the tail-shaft of the motor, in my car there was NO SPACE for a tail-shaft, let alone mounting anything there
Non-mechanical, minimizing wear, noise, vibration, and maintenance

11 Alain April 29, 2012 at 8:54 pm

HI! i I bought your dvd and started a conversion of an hyundai accent 2001 . I try to keep the automatic transmission even though it may be a bit little less efficient than a manual trans. I was wondering if you took the main contactor from the lift you took the motor from and ,if so, since it was a 36 volt lift, how do you managed to make it work with 72 or 144 volt ?

Thank again to share your knowledge !

12 admin April 30, 2012 at 7:32 am

Hi Alain.

I did use a “forklift-style” contactor, but not one from the forklift the motor came from. The coil in a contactor is designed to run a certain voltage. That voltage creates the magnetic field that pulls the contactor shut, and completes the circuit for the electric motor. The power for the coil vs the circuit it completes are totally separate. You are not going to find a coil designed to run at 144 volts. However, ones that run at 12V are very common. Get a contactor that uses a 12V coil. Then connect that to the car’s 12V system, and have it turn and and off with the run position of the key switch.

13 moogy July 12, 2012 at 7:50 pm

Hello Ben
1.how do we determine the amps the controller should have for a certain battery pack? for example if we have a 72 volt 100 amp batteries what should be the controller’s continuous amp rating ?
2.if we need a reverse on the motorcycle how can we achieve it?
3.i read about many battery desulfation processes did you try or recommend any one of them?
4.are there any other battery that you recommend(else than lead or lithium) i heard about used nickel cadmium used packs but found none online

thank you

14 Ben N July 13, 2012 at 9:21 am

Hi Moogy,

Amperage of your motor controller really is NOT based on your batteries, other than you don’t want to be trying to suck some huge amount of power from batteries that are too small. Motor controller amperage is more based on the weight of your vehicle, what you want for acceleration, what gear you are in, and what you need for powering up hills. In general, you will want the highest amperage controller you can afford. That will make the vehicle fun to drive, and keep up with traffic in various situations.

Besides the amperage of the controller, you also need to consider with it your system voltage. 300 amps at 48 volts is only half as much horsepower as 300 amps at 96 volts. Also, the higher the voltage, the less amperage needed to do the same amount of work. Your batteries will thank you for it, as they last much longer at a lower amperage draw than a higher one. That means better range, and longer battery life.

For reverse on an electric motorcycle, you will want something called a “reversing contactor”. It’s a large power switch that flips the positive and negative cables. With a permanent magnet motor, just reversing polarity to the motor makes it spin the other direction. If using a series-wound DC motor, it will need to have four power connections on it (two for field coils, two for armature.) In that case, the reversing contactor just reverses either one or the other field or armature to make the motor spin the other way. For AC motors, reversing is dealt with at the motor controller.

I’ve heard of various desulfation processes, really can’t recommend any. I have had a dealer or two who sell “desulfating chargers” give almost unbelievable claims about them. When I offer to take one on loan, use it, and write reviews, not a single person has taken me up on it. I think the real rule of thumb is just to take care of your batteries in the first place.

There are a lot of different types of batteries out there. All the lithium types are great, but pricey. I’ve been very happy with lead-acid AGMs on my cycle. I do know a guy who built an electric motorcycle using NiCad batteries. He got his from an airport. Airplanes have laws about how often parts need to be replaced, including the batteries. NiCad is lighter than lead (weight savings is good on small airplanes!) and airplanes typically have 24V systems, so they use a 24V battery. Just three airplane batteries would get you a 72V system! Start hanging out with your pilot friends, and asking around at the local airport!

-Ben

15 Bernardo Heller September 27, 2012 at 8:30 pm

Hey Ben,
First of all, sorry if my english is not so good, but I will try to ask my question.
Here it is, I saw you employed a Pneumatic system on your car as brake, but how did you made it on the motorcycle, I haven’t seen any video with that.
Also, is there any off the shelf equipment you sugest for this aplication? (brakes)

Thanks and congrats for the great job done!
Bernardo

16 Ben N September 28, 2012 at 8:15 am

The motorcycle did not need power brakes.

The cycle has a mechanical drum brake on the rear and a simple hydraulic brake on the front. The front brake does not have vacuum-assist the way most cars do.

One reason an electric motorcycle makes such a great starter project is that everything is simpler than a car. No power brakes, no heat, no air conditioning, etc.

For an electric car conversion, many E.V. parts suppliers sell vacuum pumps and switches designed just for brake systems.

17 bob January 9, 2013 at 12:10 pm

hi ben,
my metro is an automatic transmission, do i need a standard tranny or can i make the auto tranny work?

18 Ben N January 9, 2013 at 5:22 pm

You can make an automatic work, but a manual will be both simpler and more efficient. I haven’t done an automatic, so I can’t help you with the exact details, but, yes, it is doable.

19 Paul Wilson February 16, 2013 at 1:01 am

Hello Ben,

Paul Wilson here and it’s a blessing to find someone who has taken the time to create a video series on Building Your Own Electric Car for cheap. Although converting cars with manual transmissions are cheaper, when do you plan taking on the challenge of doing a car with an automatic transmission?

20 Ben N February 16, 2013 at 1:11 pm

At this time, I really don’t have any plans on doing work on automatics. NONE of the commercially available EVs use them. Those all use either direct-drive or planetary gearing. Even the “automatic” version of the original Honda Insight used a CVT. Automatic transmissions are really a compromise to made gasoline engines easier to drive. They were never that efficient or designed for use with electric motors. A person certainly CAN use one in an EV conversion, but I’ve only ever seen that done because that’s what the car happened to have in it, not for any other reason.

On my Hybrid Pickup Truck project, that will reuse the existing manual transmission. Not only is it more efficient, but the neutral gear in the tranny will be used to allow the truck to drive in a full-electric mode!

21 Nick March 9, 2014 at 12:52 am

Hi Ben, thanks for the great resource here!

I’ve come across your old DIY Series-Hybrid Instructable where you use a propane RV generator as a range extender. I was wondering if you had any data on how much additional range you were able to attain by using this system?

Cheers,
Nick

22 Ben N March 9, 2014 at 9:58 am

The RV Generator Hybrid was a fun experiment. A friend gave me the generator for free, as it didn’t work. I was able to fix it, but I was never able to get it to run at full power. The best I could ever get was a little less than half power out of it. The Electro-Metro, running on second-hand lead-acid batteries, was only really designed for about a 20 mile range, which works fine for me, as I use it for a run-about and I live two miles from the city limits. My average trip is usually about 10 miles. With the generator running, I could extend my range to 30 miles. However, if I could have gotten the generator running at full power, it would have produced 100% of my average energy needed, so I would be able to travel an indefinate distance on the generator. Seeing as how it was only a 200cc engine, that’s pretty impressive. You don’t see many cars driving down the road on a 0.2L engine. That’s one fifth the size of the original Geo Metro 1l 3-cylinder engine. Of course the magic is that the electric motor gives the strength to accelerate the car, and the generator topping off the batteries provides the average energy required.
I learned plenty about hybrids while working on that project – mostly what NOT to do, in terms of location, cargo-space, sound-proofing etc. I still plan to build a hybrid pickup truck, using some of the experience that I gained working on the LP/Electric Metro, but that is a slow/long-term project. Once the snow melts, I should be able to get back to working on it some more.
Thanks for your interest,
-Ben

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