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Joe
06 March 2014, 2221
For an EV motorcycle, I'm thinking about using a Motenergy ME-0907 brushless DC permanent magnet motor, what would be my best option for a controller (preferably 48v)? Price is a big factor for me, so the cheaper the better but still with reliability.

yankee1919
07 March 2014, 0924
Hello Joe,

Check out Alltrax speed controller. Also do a search on this forum for speed controller, you will find a lot of info.

Tony

podolefsky
07 March 2014, 1253
Hey Joe, good to see you on the forum!

The 0907 is a brushless motor, so you'll need a brushless controller. Alltrax only makes brushed controllers.

Sevcon and Kelly both make brushless controllers that will work with that motor. Kelly is a lot cheaper, and you can program it with just a regular PC. With the Sevcon you need an expensive programmer. If you get it as a kit, it will already be programmed, but like I said it's more expensive.

Kelly used to have a bad reputation, but it seems they've gotten a lot better. Look for one that is 48V, and does slightly over the current limit of the 0907. Most likely you want one of the KBL series:

http://kellycontroller.com/general-brushless-motor-speed-controller.php

podolefsky
08 March 2014, 0828
I agree, a brushed Motenergy + Alltrax is pretty bombproof, and the price is right.

Joe and I have been chatting over email. I recommended he read Fossils to Flux and get on the forum.

We talked brushed vs brushless a bit. I suggested brushed for the same reasons, but he likes the idea of brushless. I can't blame him, they are nice, just have to keep cost and complexity in mind.

The people I know who have used Kelly's more recently are more positive, but it remains an open question.

Joe
08 March 2014, 1951
My reason for a 48v system is only for the price, I would love to have a 72v but that might be a later upgrade. Now I'm thinking of doing a ME0708, with an Alltrax controller (maybe an AXE7234). That way they are both compatible if I decide to upgrade to 72v.
Hello again, Noah! -I did buy a copy of Fossils to Flux

podolefsky
08 March 2014, 2017
Makes sense, Joe. Some issues with upgrading from 48 to 72V.

Usually motor and controller are made to run at 48 or 72, but not both. The NPX will only do 48V. The AXE 7234 will do anything from 24-72V, so you'd be OK there. But then there's the motor. The 0708 is made for 48V. If you went to 72V, you'd want to switch it out for an 0709. You *could* just get an 0709, it will work at 48V, but it won't spin as fast. The 0708 is made to do 3500 RPM at 48V. The 0709 is made to do 3500 RPM at 72V, but at 48V it will only do about 2300 RPM.

Basically, an 0709 and AXE 7234 would work at 48V, but it would be slower than an 0708. You'd only see it's full potential when up went to 72V. But if you really planned on upgrading, that might be a way to do it without having to buy a new motor.

The other issue is that adding cells later can be a problem because they won't be matched. Cells age as they're used, so if you have 16 (for 48V), after a year of use they will be sightly worn. If you add 8 more cells, they'll be brand new and behave differently. It's not that big a deal if they're just in series, you just end up being limited by the older cells. But you can have issues with the old and new cells getting out of sync.

Nothing's impossible, it's just a lot better idea to pick a voltage and build the system around it, rather than try to make a big change later on.

Joe
08 March 2014, 2114
Huh, the website I was looking at said that the 0708 was 24v-72v. Another thing I was thinking about- If I wanted more range then could I add on more batteries in parallel without changing the ones in series... So the voltage wouldn't change?

podolefsky
08 March 2014, 2124
Do you mean the 0709? Yup, it will work 24-72V, just that it works best at 72. Think of it as being "tuned" for 72V, whereas the 0708 is tuned for 48V.

I haven't seen the 0708 rated at 72V. Motenergy's specification says 48.

http://www.motenergy.com/me0708.html

Adding cells in parallel has sort of the same problems as adding in series, only worse. You really want your parallel cells to be matched, and if some are older it can cause major problems. If one parallel cell is stronger, it will provide more current than the others. Say you're pulling 100A from two cells in parallel. If they're matched, they will both do 50A. But if one is stronger, it could be 60/40, or even 80/20. That's bad for a whole bunch of reasons, the biggest being that the stronger cell can end up overworking and burning itself up.

Joe
09 March 2014, 0035
I guess the website I was on (amazon) just had the wrong info. The 0709 is definitely the better option.
I'm guessing (because I hear about it a lot) that thunderstruck motors is a trustworthy site?
And what I'm saying with the parallel batteries, if they were the same age (I don't know much about them so I'm asking) if you had 4 12v in series, that would give you 48v and then say you had 2 more in parallel, would that increase the range but keep it 48v? -just an irrelevant question


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podolefsky
09 March 2014, 0953
Thunderstruck is good, as is Electric Motorsport and EVDrives.com. I've personally bought from EVDrives and they're great folks, but I think they're all good dealers.

I see what you mean on parallel now. Very relevant question. You've got it, the voltage stays the same, you add capacity (which means more range). Two 20Ah cells in parallel basically act like one 40Ah cell.

podolefsky
09 March 2014, 0956
By the way, do you have a donor bike in mind? Finding a good donor is one of the trickiest parts of the whole thing.

Joe
09 March 2014, 1124
I've been keeping my eye on craigslist, I don't want to spend more than $500 so it's a tight situation, every once in a while I see one but they go fast


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podolefsky
09 March 2014, 1136
Yup, that's tough, but it'll come along. Feel free to post on the forum, or email me about what you found. Can let you know if it's a good donor bike.

Good luck bud!

chipper6
10 March 2014, 0027
Joe what about batteries? What's your budget/plan for those?

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Joe
10 March 2014, 0528
Right now it's anything I can find for a good price, I will probably get everything else first and then see how much money I have left