Li-ion Discharge Rates: Answers to DIY Battery Jump Starter Questions

[gideon0223]

More of a general question but thought I'd post it here.

Motorcycles are notorious for losing battery charge and not starting requiring a jump or rolling start.
Was looking to get one of these new Li-ion battery / jump start modules capable of starting a car (and charging a phone or tablet). Something like this one: http://junopower.com/collections/automobile/products/junojumpr-black-most-portable-jump-starter

My question is how do you think they are achieving this high amperage out of these batteries without damaging them? I am totally guessing its something like 6 Li-ion cells in there 3 in series and 2 parallel sets of 3 or something to get around 300 amps (6600mah) and 12+ Volts- I assume something like a 30C discharge rate for short bursts or is there some type of circuit you can design with capacitors to get you the amps you need without lowering the voltage?

How hard would it be to build one of these as a DIY project?

I ask purely out of curiosity. Thanks in advance guys...

 

[zoki85]

It isn't hard to make circuit with inductors and capacitors charged slowly by batteries, and then quickly discharged through low impedance nework. But start modules designed to perform specific tasks you describe are not so trivial.

 

[gideon0223]

Yeah, I guess I was asking more along the lines of:
Do you think this is a bunch of caps doing this? (Seems really thin for that)
Or do you think this is just some high discharge li-ion cells wired together to get the 300amps?

 

[zoki85]

I highly doubt you'll find just battery cells inside