Electric trail bike

[Drtyfun]

Great job Luke!!!! I was very impressed when I first saw the bike at the meet up last week, now i have found the thread to read along.

[troidus]

I've kicked around the idea of converting my '89 JS440 JetSki to electric. One problem is that the whole system has to be waterproof, not just water resistant. Also, boats are constant load, so there is no coasting to save power, meaning that runtime will be an issue. It should run for at least 90 minutes, or it'll be disappointing. There should also be a "reserve", some smaller pack in the battery bank that will at least get it to shore if I misjudge and run out of juice in the middle of a lake.

[knary]

Combining a backhanded compliment with spam. Well done.

[Cody1771]

Originally Posted by knary

Combining a backhanded compliment with spam. Well done.

no kidding... wicked project! awsome work.

[Luke]

So it's been a while without any updates, so here's a little one.

I've been messing with the charging system; building the charger into a portable box, and doing a bunch of invisible fussing with the electronics. It's paying off- the same battery pack gives about 25% more range than it did before. There's also a fair bit to do to make the throttle response better; MX tires on wet rocks give a lot of wheelspin.



The wooden box is the charger- it takes 1 hour to charge at home, 3 hours from the truck. With a bit more work it should be able to charge this sized pack in around 1/2 hour. For any more remote charging I'll get a generator. 3 hours is a long time to charge, especially when I have to keep my truck running.

Here's the last run of the day. I got hung up on a root hole midway through and had to lift the back of the bike out- but it's so light that that's easy. And of course, the battery ran out right at the very end.

[Mr. Fisherman]

Originally Posted by Luke

So it's been a while without any updates, so here's a little one.

I've been messing with the charging system; building the charger into a portable box, and doing a bunch of invisible fussing with the electronics. It's paying off- the same battery pack gives about 25% more range than it did before. There's also a fair bit to do to make the throttle response better; MX tires on wet rocks give a lot of wheelspin.



The wooden box is the charger- it takes 1 hour to charge at home, 3 hours from the truck. With a bit more work it should be able to charge this sized pack in around 1/2 hour. For any more remote charging I'll get a generator. 3 hours is a long time to charge, especially when I have to keep my truck running.

Here's the last run of the day. I got hung up on a root hole midway through and had to lift the back of the bike out- but it's so light that that's easy. And of course, the battery ran out right at the very end.

Lookin good!

Gotta remember to ride up hill so you can coast back

[knary]

How is throttle control working out now that you've had it out in the woods?

[Sequoia]

I read through the entire thread & didn't see anything about belt drives so I thought I would mention it.
Remember Harleys have belt drives so you should be able to find one somewhere close to what you need through
Gates Belts or ?? It's not going to save you a whole lot of weight but it is rotating weight & should help out some when you get to that point.

I can see you lightening up the cases that hold the batteries too, I know that wood fiberboard isn't light.

Great job on the build though I like it.

[Luke]

Originally Posted by knary

How is throttle control working out now that you've had it out in the woods?

It works well as long as I'm moving. Not so well when I get stuck :) Then the back wheel really likes to spin up. That makes it hard to get moving again, and is probably wasting a lot of energy.

[Luke]

Originally Posted by Sequoia

I read through the entire thread & didn't see anything about belt drives so I thought I would mention it.
Remember Harleys have belt drives so you should be able to find one somewhere close to what you need through
Gates Belts or ?? It's not going to save you a whole lot of weight but it is rotating weight & should help out some when you get to that point.

I can see you lightening up the cases that hold the batteries too, I know that wood fiberboard isn't light.

Great job on the build though I like it.

I've been talking with a local guy with a similar project. He used a belt for the primary reduction and it has been giving a bit of trouble despite careful mechanical design and construction. My tape measure and cutting torch approach would not work at all with a belt. At this point I'm going to stick with the chain but would like to use a belt eventually for the noise benefit.

As far as the battery packs, yes there is a lot of extra weight. The plastic isn't light either, and the cases and supports weigh nearly as much as the cells. That's not a big deal with these small packs, but for a bigger one it will be.

[Sequoia]

Is there a minimum distance that the batteries have to be seperated by ?

[Luke]

Originally Posted by Sequoia

Is there a minimum distance that the batteries have to be seperated by ?

It doesn't seem like it. They barely get warm, and I doubt they would overheat even if packed tight. I'd assume that wouldn't hold for all sorts of bikes or batteries, though.

[knary]

Originally Posted by Luke

It works well as long as I'm moving. Not so well when I get stuck :) Then the back wheel really likes to spin up. That makes it hard to get moving again, and is probably wasting a lot of energy.

Is there a ready solution for modulating the initial power ?

[Luke]

Originally Posted by knary

Is there a ready solution for modulating the initial power ?

No.

As in, I'm working on it but it's not ready yet.

[oregoncoast]

What about making an electric vintage trials bike? Ever thought of that?