Interesting C rate info.
As most of you know I've been doing allot of tests on various Lipo packs and I recently got an email from a Lipo factory that I thought was very interesting in regards to C rate and the various claims.
Here is a copy of the email.
Hello Danny,
In the Lipo battery industry, there's no real 70C~90C .... you know well that those are marketing stuff.
The fact is that, the positive/negative tags of Lipo cell would be burnt off at high current.
The chemistry & cell packaging materials only support a real 40C~45C indeed.
With the above background, please find our internal guidelines on C-rating as follow :
1) for 30C or below, the cell models would be subject to continuous discharge at specified C-rate, where we expect MPV 3.40~3.45V.
2) for 40C and above, you know well that the cells would have gas formation upon 100~120Amp continuous discharge.
3) those Hi-Power cells would be tested for Pulse-discharge at specified C-rate -
40C models Pulse 40C x 30sec
50C models Pulse 50C x 10~15 sec
4) along with that, the Hi-Power cells would go for 20C/30C continuous-discharge, and compare their MPV.
This is some very interesting info. Not sure I agree on the method they use to claim 40C or 50C but the fact they tell me the truth about C rates and testing is very good. I truly believe that the best method to rate a Lipo would be to use IR but then again that can easily be manipulated and the factories and resellers would quickly start claiming lower IR. That being said it could easily be tested with the ESR meter unlike C rate which is very hard to test.