So there's no way to have a Li-ion battery produce around 200amps safely. Only for a very short period of time

No.

Please don't experiement with LiIon batteries unless you know exactly what you're doing. They are seriously dangerous and it takes very little to exceed their safe operating range. There are VERY good reasons that safety circuits are used in LiIon battery packs!

 

I work in BMS, and agree that no one should mess with LiIon cells.

FWIW internal resistance of some 18650 cells i have been doing was about 15m ohms.

 

forget 200amps ffs, high capacity cells from Samsung can be discharged quite safely at about 10amps continuous and 20/30Amps for durations monitored by a BMS.

200amps is pHEV material tbh

 

Here is a typical modern Lithium Polymer battery made for powering radio-controlled model airplanes, cars and boats. It does not have a protection circuit that is in the product and charger.

There are many different sizes, this one is 3300mAh.
There are many amounts of cells up to 10 cells, this one has two cells.

Its maximum allowed CONTINUOUS current is 214A and it can produce 429A for a moment.

 

So there's no way to have a Li-ion battery produce around 200amps safely. Only for a very short period of time

Why are you so insistent on misusing a particular battery instead of getting a battery that is suitable to the application?

 

Here is a typical modern Lithium Polymer battery made for powering radio-controlled model airplanes, cars and boats. It does not have a protection circuit that is in the product and charger.

There are many different sizes, this one is 3300mAh.
There are many amounts of cells up to 10 cells, this one has two cells.

Its maximum allowed CONTINUOUS current is 214A and it can produce 429A for a moment.

I am not familiar with radio controlled kit, but that is quite serious current. Dont think its to be messed with.

is there a data sheet for these cells, i know A123 do high output cells also.

 

A123 made unusual Lithium batteries then it went bankrupt. A Chinese company wants to buy it but the US government won't let them have it.

Look at the powerful Li-Po battery cells at www.thunderpowerrc.com. The battery cells do not have datasheets, just the details listed.