Low-cost Snowmobile Electric Conversion

[sethml]

Hi all, I'm converting a 2003 Ski-Doo 380f snowmobile to electric.

First off, the motivation: I have a house in Bear Valley, CA, which is a small ski resort village where the neighborhood roads are groomed but not plowed in the winter. As such, to get around you need to snowmobile, or ski, or walk. The parking lots are kept plowed, so most people will haul up their gear/groceries/etc by car, then load them into a trailer behind a snowmobile and drive maybe a mile or two to their house. Lots of people have older two-stroke snowmobiles which are unreliable, smokey, and obnoxious. I suspect a lot of homeowners up here would happy pay $3-4k to upgrade their old snowmobile to electric power. The goals are pretty modest: 20-25 mph top speed (the speed limit on the roads is 20 mph anyway), enough torque to get up a decent hill, and maybe 10 miles of range. There are probably dozens of very similar snowmobiles up here, many of which are sitting in yards or under porches not getting used.

Here's one of my donor vehicles:

 

[sethml]

For my first build I settled on the following components:

• $1000: 2x EGO Power+ 56V batteries (one 10Ah, one 12Ah) in parallel
• Custom 3D-printed battery mounts (I'll put up the design for download later)
• $370: Golden Motor 3 KW BLDC Motor Air Cooled
• $320: Golden Motor VEC200 Controller
• 428 chain drive using 34T and 56T motorcycle sprockets to gear for a 25mph top speed at 5000 RPM at the motor
• Custom sprocket mounts MIG-welded to the existing pulley shaft coupler and motor shaft coupler
• Cycle Analyst V3 for testing - I'd find something cheaper as a battery state indicator in the future

Ripping out the existing engine and getting rid of ancient fuel was a bit of a pain. For quick and dirty testing I made a motor mount out of 2x4s and plywood. Here's what the final result looks like:

 

[sethml]

Sooo, how does it work? Sadly, the results are not great. It seems snowmobiles are far less efficient than I realized. The starting torque is insufficient - even with the VEC-200 at 200A of starting current, I sometimes have to give a push to get the snowmobile moving, and I can't get up a very steep slope. Top speed on flat ground is around 10-15 mph, pulling ~4kW (80A from the battery). Uphill is far worse. I drained the batteries in 3.3 miles driving around the village at top speed (walking speed at times) using 17.3 Ah. She needs more torque, more power, and more battery. Lowering the gearing for a 15 mph top speed would help with starting torque a bit, but wouldn't improve speed since that's power-limited.

Here are some videos:

 

[sethml]

So here's my plea to the community: help me find a better motor/controller setup! I think this would drive better:

• 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.

 

[scianiac]

I have been pondering electric tracked snow vehicles a lot recently and that was always the issue I had, they are just so damn inefficient. I wonder if in addition to lots more power of course could you make some gains in other areas like lubricating the track sliders, using a lower profile track if you're on well groomed trails only, or a lower drag (more flexible) track, and removing as much weight as possible.

I think you are going to have to add a lot more batteries and you may want to consider a different option than lots of EGOs due to cost (haven't looked at the price of those recently so maybe you are right) and voltage (20S may be a better choice) maybe an aftermarket Surron battery might be an option for an easily available turn key solution since they seem to be getting so popular. But the weight placement of these batteries may also help keep things efficient, I don't know if it's better to have more weight on the track or skis here but it's something to consider or test maybe.

As for motor and controller options to fit your budget a QS motor (there are a few options that would be suitable) and the controllers they are often paired with is one option. To focus more on the US availability a LightningRods Big Block or Big Block XL and paired with an ASI controller but that will push that budget. Could also pair an LR motor with a big VESC based controller which may be cheaper depending on which brand you go.

 

[A-DamW]

I think your batteries may be the bottleneck. Especially if they are cold.
Buy or borrow a big honkin' battery and see what that controller/motor(with appropriate gearing) can do before you go too far down the rabbit hole of wondering why ~20lbs of battery can't move ~400lbs of mass very well.

 

[Quinc]

First thing you need to do is strip down everything you can possibly take off the ski. Then check all of the bearings, brakes etc to help with rolling resistance. Next you need more battery. You should have plenty of room to build yourself a 20s4p pack capable of 400+ amps. Battery is cheap and easy to build: EVERYTHING SPIM08HP

I built one for my electric jetski:

From there configure your controller for max power, if you still do not have enough power check out the QS 138 90H. You should be able to hit 40+ ft/lbs and 5k rpms make the ski a little less of a turd. For best results probably need the QS 8000w motor. But buy a surron with snowbike kit.

 

[Hillhater]

Have you checked what rpms that motor is running at when the ski is moving at its max ground speed ?
from the photo , the motor sprocket is huge, and i suspect the motor may not be getting anywhere near it normal rpm range.
what is the overall gearing to the track drive.?
that would explain poor performance and crazy battery consumption.
personally, i would swap out that sprocket for one half its size or less, just to see what it actually does to the performance..

 

[sethml]

Have you checked what rpms that motor is running at when the ski is moving at its max ground speed ?
from the photo , the motor sprocket is huge, and i suspect the motor may not be getting anywhere near it normal rpm range.

I realize it looks ridiculous, but it's geared to run 25 mph at 5000 RPM! There's a serious gear reduction from the countershaft to the track drive. I'm not sure exactly what the reduction is, but I measured that the snowmobile moves 10.2 inches per revolution of the countershaft. I could reduce the gearing to 15 mph at 5000 RPM, but that wouldn't gain me enough torque with the current motor/controller.

Thanks for the recommendations and ideas everybody! At this point I'm leaning toward QS138 90H + 3shul C350 + 4x EGO 56V 12Ah batteries for the next iteration. The SPIM08HP batteries/packs sound really promising, but they'd complication the charging situation: this is a vehicle that'll often be in below-freezing conditions, so a permanently mounted battery would need onboard heating and charger to be useful, whereas with easily removable batteries they can be brought indoors to charge.

 

[Quinc]

I realize it looks ridiculous, but it's geared to run 25 mph at 5000 RPM! There's a serious gear reduction from the countershaft to the track drive. I'm not sure exactly what the reduction is, but I measured that the snowmobile moves 10.2 inches per revolution of the countershaft. I could reduce the gearing to 15 mph at 5000 RPM, but that wouldn't gain me enough torque with the current motor/controller.

Thanks for the recommendations and ideas everybody! At this point I'm leaning toward QS138 90H + 3shul C350 + 4x EGO 56V 12Ah batteries for the next iteration. The SPIM08HP batteries/packs sound really promising, but they'd complication the charging situation: this is a vehicle that'll often be in below-freezing conditions, so a permanently mounted battery would need onboard heating and charger to be useful, whereas with easily removable batteries they can be brought indoors to charge.

Before you try the new motor etc, Try adding a ergo 24v battery or even a dewalt 20v battery if you have them already to get 80v. That will increase your rpms significantly and allow you to gear down for more torque. For the SPIM08 batteries you can build them into a suitcase and remove them after each ride like I do with the jetski. They are heavy. 35lbs but cheap and capable of a ton of amps/power.

3 of these in series would also give you a big boost in power. Plus you can use them for your motorcycle or whatever else in the summer time.

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Or 6 of these in parallel and series would give you some big power. 480amps!

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Better yet, buy a 72v Surron. You can use the battery in the snowmobile in the winter and ride the bike around the area in the summer.

 

[Quinc]

Any updates?

 

[sethml]

I'm working on the next iteration:

• 4x EGO 12Ah 14S batteries, targeting 200A max.
• QS Motor QS138 90H for almost 3x torque at the track.
• 3shul CL700 controller (this is overkill, I also have a C350 to sub in but I wanted the extra capacity to try out).
• Motor mount using 2020 t-slot aluminum extrusion & custom plates that are being machined by SendCutSend now.

I should have all the parts in the next few days, and get it put together this week. Then time for testing in the snow.

 

[j bjork]

I dont think the CL700 is overkill, more like a good match for the motor. Sounds like your batteries are not though.
I suppose you will connect them 2 in series, 2 parallel so you get 28s 24Ah?
28s is ok, 30s would be a little better. But I think you should double up on the parallel to get a battery that can deliver the amps needed.
Or maybe look at ev modules?

 

[Quinc]

Going to want 20s at the least to get those rpms up.

 

[spinningmagnets]

If you use 48V or 52V, you can add an inverter, to make the large battery a home-power backup that provides 120V AC...

 

[Comrade]

It seems snowmobiles are far less efficient than I realized.

It also seems like you took out a 50HP gasoline engine and put in a 4HP electric motor.

 

[Philosoraptor]

I’ve been gone too long…

Second on the SPIM08 batteries. They dump power.

 

[Quinc]

Better yet get two of these and run 88volts and 25ah. with 400amps of power. For only 240$. I would do this before you waste money on another motor setup.

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