A plea for help: Help me find a motor/controller for electric snowmobile conversion: 8+kW, >20Nm, cheap!

[sethml]

I'm converting a snowmobile to electric power. My first attempt is underpowered. I need a more powerful motor & controller, and I'm a bit overwhelmed at finding a good option.

I have a description of what I'm looking for on my build thread in motor+controller:

• Cost: less than $1500 (to keep conversion cost palatable)
• Readily available in US (I don't want to wait months for AliExpress shipping from China)
• Voltage: 14S lithium (42-58.8V)
• Torque: at least 40 N•m
• Power: 8-10 kW
• RPM: at least 5000 RPM max
• Weight: doesn't matter much (more weight on the skis would help!)
• Not a Golden Motor controller (their starting torque and throttle response seem crummy and their software is awful)

For reference, the current insufficient Golden Motor setup is about 20 N•m, 4 kW, and 5000 RPM max.

What should I be looking at?

 

[mxlemming]

Hi there. Lovely place you have to live in. looks awesome.

Unfortunately, everyone finds their EV battle ends up with two things, needing a bigger motor and fighting with controllers, congratulations on getting there fairly quickly.

First question is whether the golden motor at your power level is actually getting particularly hot. A lot of the inrunners from Golden, QS et al can be run far above their rated power levels, and you have particularly cold cooling air.

If not, you might be able to just bump the power up.

If it is, I would start looking at what car auxillary drive motors you can find, or e-motorbike motors. Either a QS180 or one of the Zero motorbikes motors should be well up to task. A qs138 is more available and might cut it... people have bikes up to 70mph with them, but a snowmobile is a particularly heavy and inefficient thing with a nasty continuously heavy duty...

Controllers wise, things are even harder. Lots of people are moving to VESC, but there is a big element of luck in whether you manage to get it set up and a huge variation in hardware quality. They also tend to be very optimistically rated, common sense regarding size of device and rated current applies. They get used for rolling devices where people use peak power for 10seconds to accellerate then cruise along at 1/3 power. If you stump up the cash, ASI8000 (shudder, programming reputed to be a nightmare) seems to be the most sensibly rated... Fardriver pairs naturally with the QS motors...

I gave up on the whole controller buying thing and built my own which was a massive undertaking.

Good luck...

 

[AHicks]

After retiring with 40 years experience in snowmobiling, I have one thought to share. "Cheap" and "snowmobile" are mutually exclusive terms......

Nice plan, but you're going to need some pretty healthy batteries. WAY bigger than what you are thinking I believe....

 

[sethml]

mxlemming, thank you for the response! I really like the idea of open-source VESC firmware plus a QS138 90H - I think that would supply enough torque and power to make this thing workable.

Do you have any recommendations for VESC-based controllers that'll do 60V, 120+A battery current, 300+A motor phase current? The 3shul C350 is looking pretty good to me.

 

[mxlemming]

mxlemming, thank you for the response! I really like the idea of open-source VESC firmware plus a QS138 90H - I think that would supply enough torque and power to make this thing workable.

Do you have any recommendations for VESC-based controllers that'll do 60V, 120+A battery current, 300+A motor phase current? The 3shul C350 is looking pretty good to me.

There are not many VESCs that can do this kind of current. 3Shul is one, EBMX is another, but not properly released so far. There are rumours of a Trampa 100500 coming out (the 100250 and 75300 really are not capable of those currents for much time but the 100500 will be for sure). A guy called HarryNator is also making some that can definitely do that kind of current, but not sure if he is selling, and Team Triforce make a beefy one A400S V2 but IIRC he basically does not bother to actually make them except by request.

I try not to recommend one brand over another, I chat with the 3Shul maker, he's a nice guy and very active helping DIYers make their own boards, but I never had personal experience with the Shul boards, or any other VESC except my home made boards.

It appears QS138 is 2x the weight of your current golden motor, so you can basically expect... 2x the power. Perhaps a bit more.

 

[j bjork]

I think you should double up on your currents. Not much use of a 138 90h with pA in the 300 range, more 6-800 or something.
If you plan to run high power for long you might have to turn it down a bit, but rather get more controller than you can use than less.