# Planning a first conversion: Honda Trail 90. Need help!



## caramelzappa (Mar 5, 2009)

Hi, I've been wanting to built an EV for a while, going as so far as to buy a donor car years ago, but the reality of time and money kept me from finishing that project.

I've been thinking of starting again, but starting much smaller. I found an incredibly cheap Honda Trail 90 in my area and I'm considering picking it up and converting it, but I could use some input.

I don't have incredibly high goals for this project, for me it's kind of an introduction to building an EV and not meant to be a daily driver or anything like that. It would be nice if it could get up to 35-40mph so I could keep up with traffic and range wouldn't need to be much. 10 miles would be plenty.

My initial instinct is to go for a hub motor. I realize there are drawbacks in efficiency and added unsprung weight, but the bike is so small that a hub motor would dramatically increase the amount of space I have for batteries.

Where I'm stumped here is what hub motors are appropriate for a modest motorcycle and where to get them, most of what I'm seeing is meant for bicycles, and I imagine I'd need something bigger. Any ideas?

Other than that I figured I'd go lithium. From what I've seen the price differences between lithium and lead are so small nowdays that buying lead seems like a waste, and the size of lithium cells alows me to be a lot more clever in how I fit them on the bike. I think I could fit quite a few of the 40Ah CALB cells EVWest is selling. Certainly enough for 48volts.

Any input or resources would be appreciated, especially regarding hub motors. I can't find much info on using them in a motorcycle. Thanks!


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## Duncan (Dec 8, 2008)

Hi welcome
My tuppence worth
Go for a bike hubmotor - you can get 1000watt units that will be OK for that
it's not exactly a speed demon!

Have a look at RC batteries - Lithium Poly
Not safe enough for a car but probably fine for a bike and you will be able to get them a lot cheaper


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## caramelzappa (Mar 5, 2009)

Thanks for your input!

I guess I didn't consider that an ebike hubmotor would be enough, but I'm finding some of them at 3000w+, well over the legal limit for ebikes that get 20mph. And the trail is pretty light.

Maybe a kit like this will work well?

http://www.alibaba.com/product-detail/High-speed-100km-h-high-torque_1786934037.html

Something like the Cromotor would be perfect, but it seems that they're sold out and even though it says they're accepting pre-orders there's no way to do so. http://greyborgusa.com/product/cromotor-rim/#reviews


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## RIPPERTON (Jan 26, 2010)

Enertrac
http://www.enertrac.net/product.php

QS Motor
http://www.hs-escooter.com/sdp/1012764/4/pl-4958252/0/Product.html

Big Hub Posty
http://www.diyelectriccar.com/forums/showthread.php/e-mail-ripperton-electric-posty-bike-63748.html


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## RIPPERTON (Jan 26, 2010)

This 8kw rated motor is 200mm wide at the axle but could be reduced to the 165mm that the CT90 needs between the swingarm, its 14".

http://www.hs-escooter.com/sdp/1012...nch_brushless_hub_motor_electric_scooter.html

Heres a 17"
http://www.hs-escooter.com/sdp/1012...17inch_wheel_hub_motor_for_Electric_moto.html


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## jonescg (Nov 3, 2010)

Yep - definitely go for a hub motor if you want good range and modest power. More room for batteries, basically.

CALB cells are great for scooters as the large format makes them easy to load into the base. However on a motorcycle it will require some more thought. Consider straddling the frame with a saddle-pack, or go for a single monolith if the frame permits.


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## caramelzappa (Mar 5, 2009)

Thanks for the responses! The enertrac is a little much but I think something from QS motors will be perfect for what I'm going for.

That dual hub motor Posty is looking great! Can't wait to see when you get it on the road!

Looking at dimensions and roughly guessing I think I can fit about 12 of the CALB cells low into the frame, and then I'd add more in a saddle-pack. Once I have the bike in my garage and the ice removed I'll do some cardboard mockups and see what makes the most sense.

So here's a question: How powerful of a motor do you guys think I'll need? Do you think a 3KW hub motor will be enough to push the CT90 at 40ish mph?


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## samwichse (Jan 28, 2012)

4 HP should get you 40mph no problem. I had a 49cc Honda rated at 1.5 HP and it would do 30 easy and 35 WOT.


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## caramelzappa (Mar 5, 2009)

Picked up a Trail 90 today! 

The guy selling it was really into it, and while it's going to be a project he clearly put a lot of work into it. He started talking about how he just changed the oil and filled up the gas tank. It even has a brand new battery. Didn't have the heart to tell him I'd be gutting it anyways. The bike was a steal at $500. The only immediate thing it's going to need is a new seat cover.

Now I have to find some time to take the ICE out, and start planning how I'm going to fit my batteries.


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## Yabert (Feb 7, 2010)

Hi, I like your small CT 90 project.
IMHO, if you can squeeze 6 or 7 Nissan leaf cell (7,4v and 60Ah per can) where the ICE was, that will be good. Or maybe a smaller 2 or 3 Kwh battery from a chevy Volt (45v and 45Ah or 68v and 45Ah) see picture.

About the motor, you can maybe put a small 3 to 5Kw motor on the swingarm. I don't say it's a better option than a hub motor, but it's another option. Exemple on Goldenmotor page.

Good luck.


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## caramelzappa (Mar 5, 2009)

Yabert said:


> Hi, I like your small CT 90 project.
> IMHO, if you can squeeze 6 or 7 Nissan leaf cell (7,4v and 60Ah per can) where the ICE was, that will be good. Or maybe a smaller 2 or 3 Kwh battery from a chevy Volt (45v and 45Ah or 68v and 45Ah) see picture.
> 
> About the motor, you can maybe put a small 3 to 5Kw motor on the swingarm. I don't say it's a better option than a hub motor, but it's another option. Exemple on Goldenmotor page.
> ...


Thanks for your input!

It looks like I can definitely fit at least 5 leaf cells where the motor used to be, and I could set up 3 more on each side of the rear wheel like saddle bags while retaining the luggage rack. There would be plenty of room above the 5 pack for the controller/contactor/dcdc/etc. 11 total cells for 81.4v. 4.8kwh. Seems like plenty for such a small bike. Probably overkill. But it's nice to know I can fit so many.

I've been interested in these cells for a while since they seem to be some of the best $/wh around, but I'm a little concerned about charging and BMS. Most of the people I've seen use them either use their own custom BMS (which is too daunting for a newbie like me) or use no BMS at all, which seem risky. Yes they are cheaper than other lithium options, but it's still a decent investment. It does seem like a great option but I think I need to research it further before taking the plunge. I also just like how the leaf modules look. They look amazing in this Royal Enfield Conversion https://www.youtube.com/watch?v=rvjDo8ZO7bI He managed to mount them without any welding, and it looks really clean.

The volt modules are too big to comfortably fit on the bike.

I hadn't considered a swingarm mount. It makes sense though, and it would allow me to retain the bike's original brakes, potentially saving some money (The brakes were recently redone) It's also allow me to change gear ratios which to me is the biggest problem with hub motors. I'll check out goldenmotor.

I haven't had time to do anything with the bike yet, though my new seat arrived! Next week I'm going to have some time so I'll start removing the engine. It runs but right now it's leaking fuel. Messy and dangerous, I can't wait to yank it out.


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## Yabert (Feb 7, 2010)

I think you found a good example by the Royal Enfield Conversion, but keep in mind that kind of cells stacking without protection should never see any water.

About BMS, I think the best solution is to learn how work a lithium cell, understand it, and after that simply use a cheap hobby balancing charger to always top balance the cells. Then, you use a cycle analyst to have data during discharge and you are your own BMS.
Most low cost balancing charger are only available to balance a max of 12 to 14 cells in series. That imply a max voltage of 45v to 52v nominal... can be enough for your 40 mph requirement.

Except that, maybe it should be interesting to informe you that you can probably find a used 6'' forklift motor / golf cart motor with his controller for next to nothing or use a 48v Alltrax controller.
Another good supplier for you: http://www.evdrives.com/category_s/1860.htm


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## caramelzappa (Mar 5, 2009)

So I stumbled on something interesting. There's a local craigslist add for an Electicross Drift for $1000 with a dead battery. Would it be worth it to buy it and use the motor/controller/charger? Seems like a sgood deal to me but I'm having trouble finding any specs on the thing.


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## marcexec (Feb 11, 2009)

Well, if it's just the battery, why not fix it?
Regarding hub motors, also have a look at the scooter sized ones from "John in CR": http://endless-sphere.com/forums/viewtopic.php?f=31&t=47607 & http://endless-sphere.com/forums/viewtopic.php?f=31&t=46898


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