car jump pack build lipo

[petehall347]

just had a brainwave .
i have here a good set of 18650 cells from a 36v pack . and am wondering how easy and if it will work to be arranged for a 12v jump pack for cars etc . .
just wondering about charging it .. i know it will need the correct bms . its the charger bit i am stuck on .. will a linear charger work ?

[eccerr0r]

Re: car jump pack build lipo

Was wondering about those jump packs. While I can't say it's impossible to direct start a car starter with a pack "big enough"...I'd say one would need some 100 odd 18650s to do it safely, and end up wasting a lot of reserve...

Or is it simply a large enough pack to provide enough juice to charge the lead acid pack...

Think the latter is a lot easier.

Anyway... it depends on the BMS whether you can just randomly charge it with whatever charger you have. Main issue is that probably 3S is too little, 4S is too much, you need a converter to get to 14.4V and...

[diif]

Re: car jump pack build lipo

I've used one to start a completely flat 3.0L v6 Tiguan.
It has 6 or 8 cells inside and a boat load of diodes.

[eccerr0r]

Re: car jump pack build lipo

would be interesting to know if it was 6 or 8...?
I suppose depending on the cells, 4P should supply enough current to direct start a car, just not through the cigarette lighter.