Ways to protect MMM when used with subpar batts

[himalaya]

Originally Posted by shaunjohnson

what is a GOOD low resistance?
i'm gonna test the resistance of my turnigy today

I follow my equation to make the judge:

IR ≤ 370*S/(Ah*C)， mΩ， @23℃

This equation is just my personal summarization, none official. It came from my observation to many LiPo discharge curves officially published by manufacturers as well as third party test guys. I found at the middle of discharge process all decent LiPo cells drop their voltage to around 3.4V/cell under full C-rating discharge current, that is roughly 370mV voltage drop, 10% of LiPo norminal voltage, S is the number of serial cells in a pack, Ah is the norminal capacity, C is the rated maximum discharge rate.

Note temperaure plays HUGE role in IR performance, IR can be doubled when temperature drops 20+ degrees. That is one of the reasons why there are more LiPo puff complains in winter.

I wrote a short article on this:
http://bbs.rcfans.com/viewthread.php?tid=236520
Sorry it was written in Chinese, but the graphs and simple calculation process will make some sense.