[Passedyouby]

Good morning everyone!

I know this is an odd, and potentially unrealistic, conversion and I figure I should lay down some basic expectations. My friends and I all have 2018-2019, high performance, sleds so I am not looking to break any land speed records, or reach unattainable ranges. In fact one weekend per year we all bring circa 1970s machines up for a 20mile ride, and that is the purpose of this build.

Current hardware-
-ME1115 12.5kw continuous, 25kw peak.
-5kw Li-ion batteries wired in a 24s configuration with 110A continuous, 300A burst.
-qty 2 150A Daly BMS
- Altrax 72400 controller.
-battery thermal management system
-12v LiFePO4 battery to run electronics

Again, not looking to break any land speed records, goal is to cruise at 30mph and a total of 20 miles. If you're trying to do some quick math you with notice my 5kw battery will not survive for 20miles, and that's where the help is required from all of you!!

Help needed-
As noted above, I need more range, plus it would be an absolute riot adding a generator to an electric sled (you would have to know my friends). I understand "diy hybrid" usually fails due to the massive power requirements needed for a car, but on a sled, I'm thinking this is a different animal. Also as an added bonus, the genny only needs to supplement the batteries, and at the 10 mile mark we all stop the sleds for 45minutes, chat about these old crappy sleds, then keep riding. During this time the genny would be able to nearly recharge the batteries. Is this a feasible idea???

I initially was shopping DC gents, but my pack needs an input voltage of 100.4v to charge and I struggled to find a DC system with high enough voltage. Then I got thinking AND THIS IS WHERE I REALLY NEED SOME HELP, can I use a standard 110v AC generator with a rectifier to bring me over to 110v DC?? Then either use a buck converter to drop the 10v, or maybe simply slow down the generators RPMs a bit?

Okay, I'm all ears!! Thoughts? How can I make this happen? Let's ignore physical space limitations and talk the science only please!

Cheers

 

[remy_martian]

I'd put the generator/augmented-battery in a Ski-doo Caboose, or one of the more recent variants of it. I wouldn't add anything more to the sled, as you don't want to add weight for both handling and flotation (in powder) considerations.

I'd also go battery swap (via contactors or cable connectors) instead of generator.

 

[Passedyouby]

I'd put the generator/augmented-battery in a Ski-doo Caboose, or one of the more recent variants of it. I wouldn't add anything more to the sled, as you don't want to add weight for both handling and flotation (in powder) considerations.

I'd also go battery swap (via contactors or cable connectors) instead of generator.

Thank you remy for the reply!

I have flirted with the 'caboose' thought. And yes, I agree more batteries is the most logical solution, we are extremely isolated and I worry that a gasoline option needs to be implemented, even if small. (Range anxiety am I right? Haha).

Let's say I did do a caboose. How would I get that power from the genny to the batteries other than an onboard charger? Is my rectifier option valid? I worry about my inability to regulate a load, and wish I could find some sort of solar controller that works at these voltages.

I'm open to ideas

 

[Passedyouby]

I'd put the generator/augmented-battery in a Ski-doo Caboose, or one of the more recent variants of it. I wouldn't add anything more to the sled, as you don't want to add weight for both handling and flotation (in powder) considerations.

I'd also go battery swap (via contactors or cable connectors) instead of generator.

Also good call on the handling. It's been a heavy concern of mine. The good news is there at almost 100 sleds on this ride and the trail is well packed for the event, so powder isn't too likely

 

[remy_martian]

Lithium is a current charged device, so simply applying a voltage source is a very bad idea.

Yes, you'll need a charger. I'd just go with a small Honda 2kW and use a 120V lithium charger.

Been a few decades since I've run sleds...I do remember how awful the heavier machines were, even on packed trails and what a joy the lightweight aluminum machines were. Especially if minimally powered (no offense, but 20hp...).

 

[Passedyouby]

Lithium is a current charged device, so simply applying a voltage source is a very bad idea.

Yes, you'll need a charger. I'd just go with a small Honda 2kW and use a 120V lithium charger.

Been a few decades since I've run sleds...I do remember how awful the heavier machines were, even on packed trails and what a joy the lightweight aluminum machines were. Especially if minimally powered (no offense, but 20hp...).

Ha! Yes, the modern sleds have come A LONG WAY in the past couple of decades. This old school sled conversion is for fun, not practical uses. The good news is the motor and parts removed from this SOB weighed about 114lbs, so I have some wiggle room to add stuff..

Hmm on the lithium charging comment. I've been charging a 12s pack of mine via a bench top power supply, but may need to revisit that.

Back to this project. I'm struggling to find a lithium charger with adjustable output (100.4v is my target). Do you have suggestions? So many knockoffs out there

 

[remy_martian]

Be patient - there are others on here who play in the range you are who can make expert recommendations and share war stories and will chime in during the next while

 

[wjbitner]

This guy in the norwegian area of the world can probably give you some ideas on the snowmobile conversion. He's done lots of electric vehicles and adapts to each type of vehicle.

 

[Passedyouby]

This guy in the norwegian area of the world can probably give you some ideas on the snowmobile conversion. He's done lots of electric vehicles and adapts to each type of vehicle.

Good morning!

Yes!! He is actively building one right now and I am constantly checking his page for the latest updates etc. Ironically he also choose the ME1115 for his build!

Good eye wjbitner.

 

[green caveman]

Ha! Yes, the modern sleds have come A LONG WAY in the past couple of decades. This old school sled conversion is for fun, not practical uses. The good news is the motor and parts removed from this SOB weighed about 114lbs, so I have some wiggle room to add stuff..

Hmm on the lithium charging comment. I've been charging a 12s pack of mine via a bench top power supply, but may need to revisit that.

Back to this project. I'm struggling to find a lithium charger with adjustable output (100.4v is my target). Do you have suggestions? So many knockoffs out there

Check the threads on hacking the Zivan NG1/NG3. There are a couple of resistor you can change out that control the final voltage. Some thought that the lead acid charging will work for you as long as the BMS is going to kill the charging. (Pretty much all charging is constant current/constant voltage - charging is not the problem it's knowing when to stop!).

 

[Electric Forklift Guy]

Good morning everyone!

I know this is an odd, and potentially unrealistic, conversion and I figure I should lay down some basic expectations. My friends and I all have 2018-2019, high performance, sleds so I am not looking to break any land speed records, or reach unattainable ranges. In fact one weekend per year we all bring circa 1970s machines up for a 20mile ride, and that is the purpose of this build.

Current hardware-
-ME1115 12.5kw continuous, 25kw peak.
-5kw Li-ion batteries wired in a 24s configuration with 110A continuous, 300A burst.
-qty 2 150A Daly BMS
- Altrax 72400 controller.
-battery thermal management system
-12v LiFePO4 battery to run electronics

Again, not looking to break any land speed records, goal is to cruise at 30mph and a total of 20 miles. If you're trying to do some quick math you with notice my 5kw battery will not survive for 20miles, and that's where the help is required from all of you!!

Help needed-
As noted above, I need more range, plus it would be an absolute riot adding a generator to an electric sled (you would have to know my friends). I understand "diy hybrid" usually fails due to the massive power requirements needed for a car, but on a sled, I'm thinking this is a different animal. Also as an added bonus, the genny only needs to supplement the batteries, and at the 10 mile mark we all stop the sleds for 45minutes, chat about these old crappy sleds, then keep riding. During this time the genny would be able to nearly recharge the batteries. Is this a feasible idea???

I initially was shopping DC gents, but my pack needs an input voltage of 100.4v to charge and I struggled to find a DC system with high enough voltage. Then I got thinking AND THIS IS WHERE I REALLY NEED SOME HELP, can I use a standard 110v AC generator with a rectifier to bring me over to 110v DC?? Then either use a buck converter to drop the 10v, or maybe simply slow down the generators RPMs a bit?

Okay, I'm all ears!! Thoughts? How can I make this happen? Let's ignore physical space limitations and talk the science only please!

Cheers

The numbers for electric car range is going to be vastly different than a snowmobile (the rolling resistance is much higher)

Fortunately

 

[Electric Forklift Guy]

The numbers for electric car range is going to be vastly different than a snowmobile (the rolling resistance is much higher)

Fortunately

Oops....continuing
Fortunately there's an easy way to get a semi-accurate estimate

1 gal of gasoline= 33 Kilowatt hours.

So just drive a regular snow mobile 20 miles at 30 mile per hour and see how much fuel it uses.

Its rough , but it will show you if what you want is feasible.

 

[remy_martian]

What about a 2 stroke engine 😂

 

[brian_]

What about a 2 stroke engine 😂

I doubt that there's enough difference in efficiency between 2-stroke and 4-stroke engines in a modern production snowmobile to matter to this rough estimation, but I suppose one could pick a different value for 2-strokes (such as 1 gal of gasoline = 30 kilowatt-hours).

 

[Passedyouby]

I doubt that there's enough difference in efficiency between 2-stroke and 4-stroke engines in a modern production snowmobile to matter to this rough estimation.

I worry about this calculation because on any of our sleds (2008-2020) we get between 11-13mpg. This would mean that I would need approx 150kw of power for a casual 55miles or so. There is a sled called Tiaga, released this year, that offers a 45kw battery pack and offers an 80mile range. That would equate to what, 50mpg? Doesnt quite add up.

Did my best to calculate the friction of snow on the skis, track friction, etc and used that data to calculate how many NM of force would be needed to maintain speed at 35mph
Fount the needed amps for my motor to produce that output and estimate I will need 8-9kw for a 20mile trip.

 

[Passedyouby]

Additionally. Has anyone here disassembled an old EV battery and found a heating element internally? I have found it twice now, but and confused because the heating element is doing something odd. If anyone has seen this let me know. Would love to discuss!

 

[brian_]

I worry about this calculation because on any of our sleds (2008-2020) we get between 11-13mpg. This would mean that I would need approx 150kw of power for a casual 55miles or so.

That's 150 kWh (of energy), not 150 kW (which would be power)...
but yes, snowmobiles are horribly energy-hungry for their size.

There is a sled called Tiaga, released this year, that offers a 45kw battery pack and offers an 80mile range. That would equate to what, 50mpg? Doesnt quite add up.

The claimed consumption for the Tiaga suggests that it is for ideal operating conditions on well-groomed trails. You probably ride in the real world instead.

Did my best to calculate the friction of snow on the skis, track friction, etc and used that data to calculate how many NM of force would be needed to maintain speed at 35mph
Fount the needed amps for my motor to produce that output and estimate I will need 8-9kw for a 20mile trip.

Excellent approach, but you really need to be clear about whether you are talking about power (kW) or energy (kWh). Did you calculate the power (in watts) by multiplying the force (in newtons, N, not Nm) by the speed (in metres per second), or did you calculate the energy (in watt-hours) by multiplying the force (in newtons, N, not Nm) by the distance (in metres) and dividing by the 3600 seconds in an hour? I don't know if you estimated 8-9 kW (of power) to maintain 35 mph, or 8-9 kWh (of energy) to travel 20 miles.

 

[brian_]

Additionally. Has anyone here disassembled an old EV battery and found a heating element internally? I have found it twice now, but and confused because the heating element is doing something odd. If anyone has seen this let me know. Would love to discuss!

I haven't disassembled an EV battery, but some do have a heating element internally. That would typically be in a battery without liquid thermal management (cooling), such as a Leaf. It is there to keep temperature during storage from getting low enough to damage the battery, and getting temperature up enough to allow charging... both typically while plugged into a charging station, but the Leaf can run the heaters to protect the battery while parked and unplugged.

 

[Passedyouby]

That's 150 kWh (of energy), not 150 kW (which would be power)...
but yes, snowmobiles are horribly energy-hungry for their size.

The claimed consumption for the Tiaga suggests that it is for ideal operating conditions on well-groomed trails. You probably ride in the real world instead.




Excellent approach, but you really need to be clear about whether you are talking about power (kW) or energy (kWh). Did you calculate the power (in watts) by multiplying the force (in newtons, N, not Nm) by the speed (in metres per second), or did you calculate the energy (in watt-hours) by multiplying the force (in newtons, N, not Nm) by the distance (in metres) and dividing by the 3600 seconds in an hour? I don't know if you estimated 8-9 kW (of power) to maintain 35 mph, or 8-9 kWh (of energy) to travel 20 miles.

Doh. Good call. My appologies on the poor description with kW and kWh. Trying to reply on the forum without getting busted for not paying attention to this horrible movie with the Wifey.

 

[remy_martian]

I doubt that there's enough difference in efficiency between 2-stroke and 4-stroke engines in a modern production snowmobile to matter to this rough estimation, but I suppose one could pick a different value for 2-strokes (such as 1 gal of gasoline = 30 kilowatt-hours).

You're probably right, Brian, though the 2 stroke will run at much higher rpm making for a much better power/weight ratio and...coming closer to an electric motor in terms of what's between the track and crankshaft for gear ratios.

Can you find the engine torque curve? Back in my day they used to publish the drive ratios, top speeds etc in snowmobile mags