Replacing Skidoo 12v SLA with LiFePo4

Batteries, Chargers, and Battery Management Systems.
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Ypedal   100 GW

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Replacing Skidoo 12v SLA with LiFePo4

Post by Ypedal » Dec 20 2010 8:44pm

A while back, i built a lipo pack for a friend with a Honda CRF450 to power an HID headlight, for winter he rides a Ski-Doo and this is another project for more light and at the same time lighter battery !

Ski-Doo - Renegade 800cc 2 stroke
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Re: Replacing Skidoo 12v SLA with LiFePo4

Post by Ypedal » Dec 20 2010 8:46pm

Stock it has an 18ah SLA.. located just behind the exhaust..
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Re: Replacing Skidoo 12v SLA with LiFePo4

Post by Ypedal » Dec 20 2010 8:47pm

Original plan was to use this :

( 4 cell ) 12v 10ah PSI cells.
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Re: Replacing Skidoo 12v SLA with LiFePo4

Post by Ypedal » Dec 20 2010 8:52pm

The PSI pack would be 4 lbs instead of the 20 lbs sla.. but just a little too tall.. and i mean " just " .. but to get that half inch of space we would have to relocate a bunch of stuff, including the starter relay, fuse box.. etc...

so.. a quick email to the good Dr of Bass.. and one Dealt pack arrived 4 days later !

Got it tonight.. hacked it apart..
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Re: Replacing Skidoo 12v SLA with LiFePo4

Post by Ypedal » Dec 20 2010 8:54pm

Going minimalist, 8 cells, 4S 2P

4.6ah , 12v !
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Re: Replacing Skidoo 12v SLA with LiFePo4

Post by Ypedal » Dec 20 2010 8:58pm

For lights.. a pair of Lumenators ! 8)
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Re: Replacing Skidoo 12v SLA with LiFePo4

Post by Ypedal » Dec 20 2010 9:02pm

Now, a problem i have to deal with is that the Lumenators will work at 13.x volts, but don't light up fully, i need at least 15v to light up the CL's properly.

So, after some emails, and i'm going to need help with this one but aparently i can wire up a DC-DC in series with the 12v pack and up the voltage for the light..

So.. got this :
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Re: Replacing Skidoo 12v SLA with LiFePo4

Post by Ypedal » Dec 20 2010 9:12pm

And that's where i'm at tonight.. I am grouping pairs of M1 cells in parallel, then going to wire those in series, no BMS and no monitoring, just straight up to the ski-doo in place of the SLA and away we go..

4 M1 cells x 3.65v = 14.6v , just about the hightest an SLA cell should go, i don't yet know how regulated the voltage is on the sled but we are going to find out !..

The starter was tested with a clamp on meter and registered 60 amps cold cranking, and 40 amps with the plug caps removed motor turning over without spark... so 4.5ah at 60 amps should be ok, even with sub freezing temperatures.. another item to test !!!..

Fun times !.. will update as i go !
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Re: Replacing Skidoo 12v SLA with LiFePo4

Post by Ypedal » Dec 20 2010 9:53pm

Ok.. soldered the + tabs to pair up the cells.

Had to use a small piece of copper to bridge one of the pairs..

Weird how the M1's are + and - reversed compared to almost all other cells.
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Re: Replacing Skidoo 12v SLA with LiFePo4

Post by Ypedal » Dec 20 2010 9:55pm

The - side
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Re: Replacing Skidoo 12v SLA with LiFePo4

Post by wineboyrider » Dec 20 2010 10:28pm

Charging the lifepo4 with the alternator or generator??
ES IS SAVED! THANK YOU JUSTIN.

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Re: Replacing Skidoo 12v SLA with LiFePo4

Post by Ypedal » Dec 20 2010 10:54pm

Right off the alternator ! :o
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Re: Replacing Skidoo 12v SLA with LiFePo4

Post by fechter » Dec 20 2010 11:39pm

Cool.
I want to do something like that for a motorcycle battery replacement.
The typical voltage when the engine is running is around 14v. If you divide this by 4 cells, that gives you 3.5v per cell, which is a bit on the low side for LiFePO4, but might be good enough. I don't think you'd have to worry about shortening the life by holding them at that voltage for long periods. If you had some real simple 3.6v or so shunts, no cell should get overvoltage.

If you forgot to turn off the ignition or left a light on, you could run one to the destruct point, so an active cutoff would be the safest thing, but a pain in the butt to implement.
It seems like you can take them down to zero without killing them immediately, but a cell reversal is instant death. Some kind of beefy diode across each cell to prevent reversal in the event of overdischarge might be better than nothing.
"One test is worth a thousand opinions"

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Re: Replacing Skidoo 12v SLA with LiFePo4

Post by trappermike » Dec 21 2010 12:40am

Ypedal,I can give some info on the subject of Skidoo's,I was the Skidoo mechanic and warranty repair mechanic for all Skidoo's in the Yukon for 5 years,so I know a few things about them...
First,all the battery does in a Skidoo is operate the starter motor,period. Skidoo models without electric start have no battery,and only use a regulator(that limits voltage to about 13-14v by dumping excess volts to ground,voltage keeps climbing with revs without one) in the charging/electrical system,in fact the lights and acc. are running on AC power from the motors charging coils. A model with a battery and electric start has a regulator/rectifier so the battery will be charged with DC current. Start the machine and check voltage at the battery terminals and at the headlight bulb socket to test generator output voltage at various rpms. I don't know if this will be correct for charging a LiFePO4 battery,maybe rig a charger into the system somehow if necessary...
Will Li-FePO4 hold charge for long periods in extreme cold,maybe how cold it gets where you live matters a bit...I think it will be fine,it only has to spin the motor for a couple of seconds to start it. You still have a recoil starter in emergencies anyway.
As for the stock Skidoo headlight bulb,they were a normal quartz bulb,I used to replace them with a higher watt bulb from the auto-parts store,a stock bulb is usually 55H/50L(Watts),a good replacement is a 100H/80L. I used these bulbs in my truck's Bosch headlights too and they really light things up! I wouldn't worry about the extra current draw,the generator is made to handle extra acc. like heated hand grips etc.
A good idea to lighten your sled! :)

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Re: Replacing Skidoo 12v SLA with LiFePo4

Post by texaspyro » Dec 21 2010 5:54am

There is virtually no difference in capacity of a A123 cell charged to 3.4V and 3.65V See the first post in my thread http://endless-sphere.com/forums/viewto ... er+effects where I tested lots of A123 parameters and behaviors.

Also, A123 recommends a "float" charge voltage of 3.45V From my testing, it can take quite a bit more time to fully charge the cells at the lower voltages. If your alternator is charging the pack at a little to high a voltage, you can use some seriesed diodes to drop the voltage.

Wasn't Gary working on a black box LiFePO replacement for lead-acid batteries? ... a mini-bms that does all the charging/protecting of the cells that can be sealed up in the pack.

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Re: Replacing Skidoo 12v SLA with LiFePo4

Post by Ypedal » Dec 25 2010 1:12pm

Christmas day, relaxing at home, and working on this project.. awsome !

So i cut some pieces of G10/bakelite/fiberglass sheet stuff ( never sure what to call it ) to layer between the pairs of cells.
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Re: Replacing Skidoo 12v SLA with LiFePo4

Post by Ypedal » Dec 25 2010 1:13pm

cut some squares of copper sheet.. and cleaned up the edges with a grinding disk to prep for solder...

edit to add : after grinding down to shiny copper, i cleaned it with solvent before soldering, even dirty fingers can give you grief when trying to get a quick clean solder, always wipe down with solvent and try not to touch the spot you plan to solder !
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Re: Replacing Skidoo 12v SLA with LiFePo4

Post by Ypedal » Dec 25 2010 1:16pm

Covering neighboring cells, just in case, turned up the hakko station to max... working my way criss cross.. to prevent heating one place too much for too long..
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Re: Replacing Skidoo 12v SLA with LiFePo4

Post by Ypedal » Dec 25 2010 1:17pm

This should have no problem with 60 amps..
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Re: Replacing Skidoo 12v SLA with LiFePo4

Post by Ypedal » Dec 25 2010 1:19pm

other side, being carefull not to cover or melt the vents..
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Re: Replacing Skidoo 12v SLA with LiFePo4

Post by Ypedal » Dec 25 2010 1:24pm

after some googling.. and checking various sites like :

http://www.offroaders.com/tech/12-volt- ... e-amps.htm

I was considering double 10 gauge leads with a pair of PP45's.. however i re-evaluated this and decided on a single lenght of 10 gauge turnigy silicone wire with PP75's.. it's a short run and will be in cold weather at all times so this will do ..

The A123 cells are strange in that the + and - ends of the cell are reversed compared to any and all other cells i've ever had my hands on.
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Re: Replacing Skidoo 12v SLA with LiFePo4

Post by Ypedal » Dec 25 2010 2:25pm

I was about to seal it up... then decided to install ballancing leads, figured i'd kick myself for not doing this once installed on the machine and questioning the ballance of the cells...

Installed a 7 pin connector, and started from the + end... Doh.... the HK battery medic and celllog meters want to start from the negative...... grrrrrrr... un-soldered.. and re-soldered them into the right order.
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Re: Replacing Skidoo 12v SLA with LiFePo4

Post by Ypedal » Dec 25 2010 2:27pm

Done !

All i have to do now is box this sucker up and seal it from water..
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Re: Replacing Skidoo 12v SLA with LiFePo4

Post by Ypedal » Dec 27 2010 8:42pm

Today i got busy with cutting up and bending some ABS palstic..

Started with a cardboard template, got a rough idea of how i wanted it.. basically trying to keep it water-tight so less seams the better ...
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Re: Replacing Skidoo 12v SLA with LiFePo4

Post by Ypedal » Dec 27 2010 8:44pm

Getting better at bending this stuff..

Used Tuck Tape and went up the sides of the box, one more layer to keep out any possible moisture.. then backed it up with lots of hot glue...
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