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Discussion Starter · #1 ·
Starting this post to showcase an electric snowmobile I am building from an old 1980s donor. I am 2 months into the build and finally took my first test ride this evening! From building the lithium 96v packs, choosing an AC motor, designing a heating system for the batteries while sitting, but also cool them and the motor while underway, programing an arduino based display, and more.

This has been an absolute blast to design, learn, and almost die throughout the process. Since I am deep into the build, I will update every day with new information for the next week until we are in real time. My MUST BE COMPLETED date is feburary 13th for a particular event I am part of.

I am 100% open to suggestions and criticisms along the way.

Have a great night! Talk to you all tomorrow
 

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Discussion Starter · #4 ·
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.

Motor vehicle Automotive tire Hood Automotive design Automotive exterior


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

Automotive tire Motor vehicle Vehicle Rim Automotive exterior
 

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Discussion Starter · #5 ·
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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Discussion Starter · #7 · (Edited)
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.

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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.

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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.
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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.

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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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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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Discussion Starter · #9 ·
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

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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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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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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Discussion Starter · #13 ·
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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Discussion Starter · #15 ·
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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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?

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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Discussion Starter · #17 ·
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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Discussion Starter · #18 ·
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?



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.

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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Discussion Starter · #19 ·
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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Discussion Starter · #20 ·
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.

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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.

Orange Wood Gas Musical instrument accessory Flooring


DRUM ROLL PLEASE......

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

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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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