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newguyintown 06-10-2011 03:39 AM

Electric Motorcycle Conversion
Hi everyone, I'm new to ecomodder,
I want to convert an old motorcycle into an electric one. The engine, starter, gas tank, and fuel lines are in pretty bad shape right now. It's been sitting in the garage for like 8-10 years and the gasoline has pretty much turned to napalm. The rest of it is doing fine, aside from some dust, and sludge. There's not much rust or wear on the rest of it. For these reasons I thought it would make a good candidate for an electric vehicle conversion. I don't have photo's yet, but I'll try to get those as soon as possible. I need help as far as parts and pieces, assembly, and all the tricks and tips. I thought maybe you guys here could help me out with that.

What I know I need so far is:
Some sort of motor(not sure how many kw or horsepower it has to be yet)
A battery pack (Probably needs a matched voltage to the motor?)
A controller to regulate current flow
Some sort of throttle to send a signal to the controller
Something to measure voltage, speed, amperage, etc and display it(I think I need this but I'm not sure.)
Possibly some sort of key or lock mechanism, so that nobody takes off with it.
I think the charging can be done through the controller but I'm not sure.

I have some idea of where to get some things, but I thought there might be some people here that could offer me better options.

I'm not sure yet where to get a good motor or controller, or how big it has to be.

I found Li-ion battery cells that are 18650 cells on ebay (supposedly what they use in the battery pack for the tesla)
They're 3.8amps, and 3.7 volts. They would give me a good battery pack, but I would have to do the wiring myself. I have an idea of how to do it, and would love to have the experience of doing that part myself, instead of buying an already made battery pack.

I found a throttle at electric motorsport for $50. I'm not sure if this is the whole setup I need, or how that interacts with the controller, or if $50 is a good price.

I don't need the motorcycle to have really more than a 30 mi range or 45mph top speed, but I'll take what I can get. I don't mind doing more work on it to save money or gain experience, but I would prefer to keep the cost under $1000 if possible. I'm not sure if that's possible, but that's my goal.

Please reply with any info, or experience you'd like to share. I'd really appreciate it.

bennelson 06-10-2011 10:05 AM

Motorcycles are pretty easy to work on and convert to electric.

My motorcycle is a 12 hp Briggs and Statton E-Tek. Works well.

My batteries are Optima Yellow Tops - 55ah lead-acid, four of them, for 48 volts. The Motor is designed for up to 48v, and the controller will do 24-48V.
The controller is 300 amp max, the motor is 150 amp continuous. Motors usually peak at at least double their continuous rating, so it seems to all be a good match. It's worked great so far, at least.

Try to get components that are matched in voltage and amperage. If you don't, you will overpay for one component, but won't be able to take advantage of it because the other components are the weak link.

A $50 EV cycle throttle is most likely a Magura twist grip. It just connects to the controller with two small wires. (There's 3 wires on the throttle, but it's easy to figure out which two you need.)

My motorcycle did cost more than $1000, but a big part of that was that I used basically a new motor ($500) and all new, nice, batteries ($800). Just those two components together would blow a $1000 budget.

It is possible to build a cycle completely from used parts. So a web search for Forkencycle for an example of that.

newguyintown 06-10-2011 03:17 PM

Thanks for the reply,
I'll try to look for a matched controller/motor setup.
The throttle is a Magura twist grip, glad to hear that part won't be too hard.
Now I want to know, about dc vs ac for the motor setup. Can the batteries store either form of energy, or how does that work? Do I need an inverter?

At 55ah, 48V your battery pack had 2.64kwh of storage right?
I found on ebay(sorry can't link yet not enough posts) new lithium ion cells, that are 3.8ah, 3.7V, and work out to $1.78 a piece. That would be about $126 per kwh of storage for the cells, plus the wiring and framework etc. I was wondering if this might be a better option than looking for deep cycle marine batteries. I wouldn't mind having to do all the wiring myself, if I could save that much money on it.

Does anyone here know how much it would cost in materials to build the frame, and wire the battery pack? Another advantage I was thinking of for that, is that I could build the battery pack to the shape of the frame for a better fit.

Going off of Tesla's numbers(sorry again for no link) of $200 per kwh of storage capacity, that would price a 3kwh battery pack, at $600. A throttle is another $50 which isn't bad.

If I use a brushless motor, what kind of mechanism do I need to send the signal for the regenerative breaking?

I found a 3kw-7.5kw brushless dc motor from for $386, a 300ah controller for $385, and a 500ah controller for $466. Would that size motor be big enough to get to 45mph, and sustain it?

If that setup worked, it would be $50 for a throttle, $386 for a motor(probably need to add shipping costs to these), another $385-466 for the controller, and somewhere around $500-600 for batteries which would put me around $1400-$1500. Does that sound like a reasonable estimate?

Is anything on this setup overkill for a 30mi range, and 45mph top speed? I'll be looking for cheaper motors or controllers. I'm also going to try to "aeromod" the motorcycle so it requires less energy to run. Also would it be possible to hook up multiple motors? That might possibly be a cheaper option, if the controller for it doesn't have to get more complicated.

Thanks so much for your help (I'm subscribed to your youtube channel BTW, it's got some great info)

MPaulHolmes 06-10-2011 05:26 PM

It's not trivial to get the lithium cells into a pack. The usual method is to use like 4000 amps in a spot welder. Soldering is not recommended since it damages them. There are people that have soldered them, but my understanding is that their life is significantly reduced.

newguyintown 06-10-2011 06:11 PM

Thanks for your input MPaulHolmes. I was thinking of the method of using a box type frame, and copper strips that go across the electrodes(sorry I don't have the link right now I'll try to find it). This method, is supposed to be fairly simple, but it would still be a difficult process to get over 100 cells wired up properly. I think I'll do a small scale test, and post my results.

Ryland 06-10-2011 07:07 PM

You pretty much need to match your controller to the motor, if you use an AC motor then you need a controller that is designed for that motor, if you use a permanent magnet motor then you have many more options for controllers but you still need to make sure that it's compatible, also make sure that your controller amperage is the continues duty, not the 5 second rating and unless you want a controller with a short life then it should be over sized by maybe 10-20% if not more, because you don't want to be running your electronics at their peek all the time.

puddleglum 06-12-2011 09:02 PM

What size of motorcycle are you starting with? The size and weight of the bike is going to determine how much power you need. I've been looking at Golden Motor stuff as well but shipping costs seem fairly high and you will want to check into what US customs will charge you on imports from China. You want those costs included in your budget. Also, you haven't mentioned a charger or a BMS. You will need a charger designed to work on Lithium Ion batteries. I think Lithium is the way I would go if I was building a light bike, but I think you had better raise your budget to at least $2500 or more. I'd love to see you prove me wrong though. Have you considered the Lithium packs that they sell for E-bikes? I think they might work pretty well if you linked a few together to get the right pack size.

newguyintown 06-12-2011 09:17 PM

Thanks for the new input puddleglum, and Ryland.

Ryland, the motor and controller are sold by the same company to go together, so I think they'll match but I'm not sure how to check.

Puddleglum, I'm starting with what I think is an old dirt bike, I'll try to get some photos of it. I'm getting it from a friend, and I've seen it but didn't get to weigh it or anything yet. I pushed it and it didn't seem too heavy, but I can't give an exact figure at the moment. I'll make sure to re-adjust my budget for shipping costs. I wasn't even thinking of a BMS, I think the controller can act as a charger though. I have seen the lithium packs that they sell for E-bikes/EV's, but the pre-assembled ones come out to like $400 per kwh, and I'm trying to get that down to $170 per kwh for my low budget. I also want to learn how to wire my own battery pack, so that I know how to do it for future builds/conversions. I fear my budget may have to be $2500, but I'd really like to try to do this as cheaply as possible. I was thinking of maybe taking a golf cart motor/controller setup and reusing it. That way I wouldn't have to deal with the shipping, or matching on the controllers.

Thanks for the input everyone.

MPaulHolmes 06-12-2011 10:10 PM

The silver chair is my favorite book, Puddleglum.

Ryland 06-12-2011 11:11 PM


Originally Posted by newguyintown (Post 244750)
I'm getting it from a friend, and I've seen it but didn't get to weigh it or anything yet.

does your friend have the title for it or are you going to end up with an electric motorcycle that you can not use on the road, sure Ben Nelson was able to get a replacement title for his motorcycle but each state can vary and it's one of those tasks that I would never bother doing.


I think the controller can act as a charger though.
I've never seen a controller that can work as a charger, you could put them in the same box but they don't have any cross over in how they work that I know of that would allow them to be the same device.


I have seen the lithium packs that they sell for E-bikes/EV's, but the pre-assembled ones come out to like $400 per kwh, and I'm trying to get that down to $170 per kwh for my low budget. I also want to learn how to wire my own battery pack, so that I know how to do it for future builds/conversions.
Wiring your pack is not complex, it will be one of the easy parts of building your motorcycle so I'm not sure why you are hung up on wanting to wire your own pack, either you bolt the connections on from one battery to the next battery or if you have batteries that need to be spot welded you invest your life savings in a machine to spot weld batteries, but batteries that are light enough duty to be spot welded together are not going to hold up well to a motorcycle unless you have a ton of them, then you end up with balancing issues and that is where a BMS gets really complected and expensive and do go with Lithium batteries and don't have a battery management system then you get the cost of a lithium pack and the life of a used lead acid pack.


I was thinking of maybe taking a golf cart motor/controller setup and reusing it. That way I wouldn't have to deal with the shipping, or matching on the controllers.
The golf cart route is the one I am taking for my motorcycle only I'm going to go with a heavier duty controller at some point, at some point in the next month or two I should have a price on the parts you would need to use a golf cart motor as golf cart motors are missing a vital bearing so you can't even bench test them without destroying them that bearing is in the rear axle of the golf cart and I'm working on the parts that would allow you to use it for a hobbiest application like this, or go the route I'm going and have it bolt right on to the motorcycle, of course then you would have to use the motorcycle that I have it designed for but it will all just bolt together more or less as a kit.

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