# So I built an Electric Snowmobile.



## Scotty274 (Jul 1, 2020)

You can't torment us and not post pics mate!

Pics please!!!


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## Passedyouby (Dec 5, 2020)

Scotty274 said:


> You can't torment us and not post pics mate!
> 
> Pics please!!!


Haha! Havent you heard of the art of... SUSPENSE?! 

Sure thing. Pictures inbound


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## Passedyouby (Dec 5, 2020)

POST 2- DONOR SLED

Good morning everyone!
This project started back in mid november 2020 over a couple of beers with my buddy. 1x/year, in February, 20 of our buddies get together with 1960s-70s era snowmobiles, perfectly restored, and take a 15mile ride in Michigans upper peninsula. While my buddy, john, and I both have relics for this event, his wife does not. 

Enter the donor sled.










This steaming hunk of crap isnt even that old (1980s), but was his wife's childhood sled growing up and has been sitting outside behind a barn for over 20 years. After realizing the engine was seized, every bearing was shot, and all electrical was chewed through I was able to CONVINCE HIM WE COULD REPLACE WITH AN ELECTRIC MOTOR AND SOME BATTERIES FOR UNDER 1K USD.... yeah... right....

Thanks to the beer, he believed me and we ripped out the motor that night


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## Passedyouby (Dec 5, 2020)

I cant leave you with just that post... it leads everyone to believe this is going to be a cheaply built, hillbilly build... I promise it wasnt a $1,000 build... here are a couple of teaser images.


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## Scotty274 (Jul 1, 2020)

Passedyouby said:


> Haha! Havent you heard of the art of... SUSPENSE?!


Well it didn't much work as suspense, I went to bed, slept, and then woke up to the pics.

That said, I'm salivating waiting for more. I'm curious now.


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## Passedyouby (Dec 5, 2020)

Post 3: batteries inbound

While my buddy john and I got lost in the world of learning about the friction coefficient of plastic skis in snow, rotating mass, and predicting a final weight in an effort to understand what kind of motor to buy, I decided to order the batteries.

After 3 weeks of hounding used lithium sites every day and inputing the best deals into an excel sheet I found the best deal to date.










These turned out to be out of a mild hybrid 2014ish Mercedes s class. Originally I ordered 4 of these bad boys, but after receiving and testing down I knew I needed 4 more before they sold out.

The reason I fell in love with these packs is that, for starters, they come in a really durable and safe case that will put up with abuse. They also have not only a built in cooling loop on the top, but after tearing down I found it also has Thermo Electric Cooling (TEC)! When energized it will heat that pack, and when polarity is reversed it actually cools the cells! Too perfect to simply ignore. Check out the temperature readings in the below pic with one thermometer inside the pack and the other outside.











The next step was tearing down the packs, removing the old BMS, soldering wires onto each of the 12 cells in the pack, adding an external thermometer, adding new thermal paste to the TEC, and reassembling it all with the new BMS leads sneaking out through the bottom of the case.













































Once wired John 3d printed a box for the bms wires to be terminated inside of and the batteries were wires into 24s, 96v, packs. Each with just under 1.8kwh of power.











We chose to put the 8 batteries into a 2s 4p configuration, with each 96v pack receiving it's own daly BMS at 120A continuous 360A peak.

Total capacity 7kwh. Continuous rated current 216A at 96v. 600A at 96v peak for 30sec.


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## Steel (Feb 12, 2018)

Hello, Passedyouby ! Nice project , great motor, controller and batterypack. But I am afraid your BMS is all to small. It will shut down when you accelerate and you will have problem to adjust controller to get proper acceleration or range. You should dimension BMS after max batterypack capacity. Running in snow is heavy load, check my range test : 




Edit: did not read properly, see now that you have 2 BMS one for each 4p. Better, but still think as above is better.

BR Per


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## Passedyouby (Dec 5, 2020)

Steel said:


> Hello, Passedyouby ! Nice project , great motor, controller and batterypack. But I am afraid your BMS is all to small. It will shut down when you accelerate and you will have problem to adjust controller to get proper acceleration or range. You should dimension BMS after max batterypack capacity. Running in snow is heavy load, check my range test :
> 
> 
> 
> ...



Hello! Yes!! I actually have been following your build heavily on YouTube and am glad you found my build thread as well.

I actually have four BMSs, each one is rated for over double what the battery can safely output. The pack can output 216A continuous, the BMSs combined are rated for 480A continuous. 

I saw In your range test the bms kept shutting down. What size and brand bms did you pick again? I dont remember.

Great job on your build by the way! It's been awesome to watch.


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## Steel (Feb 12, 2018)

Hello, yes I have been watching your tread with great interest  If you have four BMS there should not be any problem. I have DALY 250 A continius and 600A max for short time.
Happy you like my build and thank you ! Hope you meet your finishing date !

BR Per


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## MattsAwesomeStuff (Aug 10, 2017)

I can't think of a vehicle less suited to EV conversion than a snowmobile. What a ridiculous project.

You guys are both awesome.

A 1 week build? Sign me up. Looks like I'll have some entertainment for Valentine's Day after all.


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## Steel (Feb 12, 2018)

I agree, it's stupid, but that's why it is so fun ! Thank you ! We paves the way for all the rest of you  BR Per


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## Passedyouby (Dec 5, 2020)

911!!! We need help!

Great day with lots of progress! Went to charge the batteries today with our 100v, 2000w, charger and something drastically failed in the charger leading to it being 100% destroyed. 

Any suggestions where we can find a new 100v DC power supply within the next few days??? Our deadline for the event is this weekend! As of right now we are looking to order 2 bench top power supplies. They only output 300w each, so it will take like 17 hours to charge.. urrgh... cant let this be what stops us!!!!


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## MattsAwesomeStuff (Aug 10, 2017)

Passedyouby said:


> Any suggestions where we can find a new 100v DC power supply within the next few days?


Depends where you are. Location matters.

There's scabby DIY solutions too. You need to recharge on the trip or is one charge sufficient?


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## Passedyouby (Dec 5, 2020)

MattsAwesomeStuff said:


> Depends where you are. Location matters.
> 
> There's scabby DIY solutions too. You need to recharge on the trip or is one charge sufficient?



Thanks matt for the reply.

Yeah, for the one recharge I hooked all the batteries up into 48 volts and used a bench top power supply to fill it up at a rate of 250wh but on the official trip i will need to top it off at the halfway point to complete the ride and will only have AC power for one hour.

To hold me over I ordered 2 110v AC to 48V DC power supply's at 1500W each, then 3 boost converters that bring 48v to 96v, each with a 1000w capacity. I think I can run all of these in parallel, right? Wont get me up to the 100.4v I was looking for, but 96v is good enough!

A little bit hillbilly. Thoughts?


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## MattsAwesomeStuff (Aug 10, 2017)

I was thinking, a 15 amp variac a beefy rectifier, a spare filter capacitor, and a fan to keep it cool while you sit still and babysit the dial and the voltmeter the entire time. Desert island kinda stuff.

Or a rewound microwave oven transformer if you can't find anything in pandemic shipping time.

Where are you charging these? You're aware that to charge 7kwh in 1 hour, would require 7kw, right? And you get flatline maxed 1800 watts out of a normal household outlet, right?



Passedyouby said:


> I think I can run all of these in parallel, right?


Mmm... blah blah floating grounds not insolated blah blah... maybe. Probably. Test it, you might blow it up.

...

Plan B, while everyone else is stretching their legs, tow your wife around in circles while she holds down the regen. Or let her sip coco and use a spare hair elastic to hold the regen.


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## Passedyouby (Dec 5, 2020)

MattsAwesomeStuff said:


> I can't think of a vehicle less suited to EV conversion than a snowmobile. What a ridiculous project.
> 
> You guys are both awesome.
> 
> A 1 week build? Sign me up. Looks like I'll have some entertainment for Valentine's Day after all.



When I saw this post yesterday, I about died. Everything about the reply was gold! Appreciate the fact you realize how ridiculous this is! Most people think I'm taking this serious, not looking for laughs


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## Passedyouby (Dec 5, 2020)

MattsAwesomeStuff said:


> I was thinking, a 15 amp variac a beefy rectifier, a spare filter capacitor, and a fan to keep it cool while you sit still and babysit the dial and the voltmeter the entire time. Desert island kinda stuff.
> 
> Or a rewound microwave oven transformer if you can't find anything in pandemic shipping time.
> 
> ...



Haha! While I like the ingenuity, adding anything else to this short time table I'm afraid is not going to be possible! Looks like it's going to be -3F next weekend so I really need to put some focus on the thermal management etc. Wont be able to half-ass that one!

LOL. Is 'blah blah blah' an official term for 'safe and by the book'? 😂😂😂


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## Passedyouby (Dec 5, 2020)

MattsAwesomeStuff said:


> Where are you charging these? You're aware that to charge 7kwh in 1 hour, would require 7kw, right? And you get flatline maxed 1800 watts out of a normal household outlet, right?



Yes, I am aware of that math. Thanks for double checking though! 

I dont need a full refill. Just a 2k or so top off. I am bringing an inverter generator rated for 3500w continuous, and using the nema outlet and a 10AWG extension cord. All of this will be dropped off prior to the event so it will be waiting for me when we get there. 

What's your profession btw? You are knowledgeable and I'm curious is it's from the hobby, or life.


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## Passedyouby (Dec 5, 2020)

Post 4- Picking and Mounting a Motor

Sizing a motor for a car, golf cart, dunes buggy, etc isnt an easy task, but at least there are data points to go after for understanding the power you will need to have success. However for us this was a shot in the dark! 

We started off looking at a 5kw brushless motor for 400USD, but quickly realized snow is a sticky SOB, and a rolling track is WILDLY inefficient.
After looking at the torque specs found on a 2020 Ski Doo 600 Ace (ICE) we found that produces around 60 ft.lbs of torque. While this doesnt translate to electric, we still set out to find a motor with comparable specs. This led us to the ME1115 from Motenergy.










After running several calculations in excel taking into account motor torque and voltage constants, we had massive fears about the range we were going to achieve (at this time we only had 3.2kwh of capacity). After many hours of motor research, we found the ME1616 which is a synchronous motor. This offers a very nice increase in torque/voltage constants over the ME1115 and also allows provides regen ability which will SLIGHTLY increase range but more importantly allows us to have a braking system!!!! This is critical since we cut out the rotor and caliper from the donor. 
This new motor is now rated for 99ft.lbs of torque which allows us to run below max load on the motor and still meet our goal of 60ft.lbs.










DRUM ROLL PLEASE......










The mounting plate isnt pretty. Forgive us, but we are on a TIME CRUNCH! Next season we will make this a bit prettier. 











Biggest issue was figuring out a gear that will work with the existing chain and the new motor!

Fyi we went with a kelly controller for this build.


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## MattsAwesomeStuff (Aug 10, 2017)

Passedyouby said:


> LOL. Is 'blah blah blah' an official term for 'safe and by the book'? 😂😂😂


No, more, same routine any time you look at paralleling power supplies. If they're not isolated, it probably won't work, so it depends on the design.



Passedyouby said:


> I dont need a full refill. Just a 2k or so top off.


Oh good. Bring a tow rope anyway.



> What's your profession btw? You are knowledgeable and I'm curious is it's from the hobby, or life.


Nothing electrical related. I had 2 years worth of electrical engineer education, but it's not the direction I went in. Gives me a decent base enough to dabble but not enough to solve actual problems or have any value. I volunteer a lot at the local makerspace, one of my passions is removing barriers to curiosity so that people who might want to try something can get their foot in the door and try a new medium without being burdened by what most people insist is the minimum entry level. Woodworking, electronics, welding, etc.



Passedyouby said:


> This offers a very nice increase in torque/voltage constants over the ME1115 and also allows provides regen ability which will SLIGHTLY increase range but more importantly allows us to have a braking system!!!! This is critical since we cut out the rotor and caliper from the donor.


Regen on a tracked vehicle in snow is going to get you pretty much nothing for range increase.

Which is good because, don't expect regen to be there. Can you put the rotor and caliper back in time? 2 is 1 and 1 is none. She'll need to drive it like there's no brake.



> This new motor is now rated for 99ft.lbs of torque which allows us to run below max load on the motor and still meet our goal of 60ft.lbs.


Good news, your motor is probably rated at 30'c or somesuch. You'll be in -20'C, a 50' difference, you can probably double or triple what you demand of your motor without making it grouchy.

Bad news, your batteries are not going to appreciate that weather. On a one-off trip, I'd almost just say pack them with styrofoam and leave the sled indoors before the trip, they might stay warm enough to not be a concern. You're going to lose a lot of range.


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## Passedyouby (Dec 5, 2020)

Post 4? 2 days until deadline
I can't keep up anymore. Day after day after day until 2am. Not really sure the order of things anymore so I guess we can talk about the 12v system? starting tomorrow I will just be posting up to date posts. 

Anyway. We need 12v to run the controller, 12v valves for the coolant system, and the water heater is a dual element 600w 12v, some need a few 12v circuits for the build. Since 96v to 12v converters are expensive around the 1kw range we elected to go with a 300w dc/dc system tied to a small, 12v, lithium bank. I actually used a solar charge controller to keep the raw incoming voltage from frying the bank. 










4, K2, packs from batteryhookup.com.










Oh yeah! There were 2 "near death" experiences during this build. I will share those stories soon. 











Night all.


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## Scotty274 (Jul 1, 2020)

Passedyouby said:


> There were 2 "near death" experiences during this build. I will share those stories soon.


You can't leave us hanging like that!


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## Passedyouby (Dec 5, 2020)

Couple more images for fun!


3d printed a box to hold 2 of the 48v packs together and hide the bms wires once the lid is on. 96v, 12s.











Nasty mess right now, but heres the chaincase, motor, part of the thermal system including the heater. 










Due to time we ended up with braided hose going to the batteries. :/ spent days 3d printing custom adaptors, but failed out pressure and vibration tests. :/

We have a total of 8 12v valves to allow full control of temperature in each pack, motor, radiator, heater, etc.


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## Passedyouby (Dec 5, 2020)

Post 5. 

Good day! 130am ripped around the lake! 1 of 3 BMS's are offline though, but we honestly didnt realize until climbing a steep hill. Coolant pump has air in the lines and is levitating, no flow, but It was still fun!


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## Passedyouby (Dec 5, 2020)

Cant seem to upload a video. Is that permitted on this forum?


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## Scotty274 (Jul 1, 2020)

Mate, this is one of the most riveting, most real time posts I've seen in a long time.

I wish I could not you a beer for the near real time seat of the pants reading this is.

I think best you can do is upload it to YouTube and plop a link here, there might be an Embed video button and we can watch the YouTube vid from here?


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## Passedyouby (Dec 5, 2020)

Scotty274 said:


> Mate, this is one of the most riveting, most real time posts I've seen in a long time.
> 
> I wish I could not you a beer for the near real time seat of the pants reading this is.
> 
> I think best you can do is upload it to YouTube and plop a link here, there might be an Embed video button and we can watch the YouTube vid from here?


😂😂😂 thank you for the comment! I'm glad somone is getting a kick out of this, because its KILLING me. Almost 3am local time right now and I need to be at work at 7am, so I will upload this weekend. Tomorrow after work is my last day to complete the project! We are heading north for the event out of town on friday....

Cheers mate! Im cracking a beer right now and celebrate with ya.


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## Scotty274 (Jul 1, 2020)

Yeah I'm gonna mix myself a Rum

You've also motivated me to get into my project this weekend.


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## Passedyouby (Dec 5, 2020)

Post 6 or7? The deadline

Ladies. Shes done. 










The DC/DC 96/12v failed on us so we are limited to a TINY amount of 12v storage to run pumps, heaters, valves, the kelly, etc. Not ideal. 
Also the 12v pump didnt have about head pressure to overcome the air trapped throughout the system, so I asses a 110v water pump with A LOT more lift and flow That I had laying around anyway for my aquarium. Just threw this in series with the other pump since the original pump is BURRIED. Added a wild amount of flow and helped us purge the air from every book and cranny. We wont run this pump unless the motor is overheating or a battery is freezing. 










Also remounted the gas tank (crazy story there!!!) And cut a hole in the face to house the 12v batteries and 110v inverter we added for the upgraded water pump. 


Our hillbilly replacement charger setup came in today. All attempts at a clean, polished. And safe build went out the window these last couple of days. What do you think of this setup?... so well done.. 😂











2, 1000w. 110v as to 48v dc converters zip ties together (overclocked a bit to 1200w each), then 2 1500w boost converters bringing that up from 48v to 96v. All stuffed into a very safe Tupperware container.











Took some neat videos. Will upload those after the weekend!

Half day of work tomorrow. Heading north at noon. 

Cheers my friends!


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## MattsAwesomeStuff (Aug 10, 2017)

Passedyouby said:


> Ladies. Shes done.


_slow clap_

Magnificent.

For all the rest of us dicking away for several years on a build, you go and get it done soup-to-nuts in a week.



> The DC/DC 96/12v failed on us so we are limited to a TINY amount of 12v storage to run pumps, heaters, valves, the kelly, etc. Not ideal.


If you want an even stupider alternative, just tap the batteries at 12v and rely on the BMS to balance out the difference from the cells you're stealing from. Will work in a pinch.



> Added a wild amount of flow and helped us purge the air from every book and cranny.


If it works it works.



> What do you think of this setup?


Temporary test setups are perfectly acceptable.

You're taking it for a weekend of testing.

Sounds good to me.



> All stuffed into a very safe Tupperware container.


... and the problem could be hardware, software, fuckin' Tupperware for all you know, all you know is "Charger no work". /Ernie Cline.

It's not even Tupperware, it's Walmart Gladware about as thick as hardened Saran wrap. One bump and she's shattered.

...

I wish you the best of luck. Hopefully your wife doesn't roll the damned thing.

Can't wait to see what shenanigans you got up to.


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## Scotty274 (Jul 1, 2020)

This is hands down the coolest "Screw it" build I've seen in a long time


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## CaptainCurt88 (Feb 16, 2021)

Great work! I'm looking forward to your videos. I joined this forum just so I could follow along any updates now that I'm hooked!


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