Originally Posted by Wayne Giles
Anytime really. Slightly surprisingly, the IR of a lipo pack is almost independant of charge state until the charge is virtually depleted. Obviously if the cell has no stored energy left then any load will collapse the voltage, but until that point is reached the IR seems to be virtually constant.
Provided you are careful to measure IR at a fixed temperature, it is the best guide to what is a good or bad lipo and correlates with best performance in practical flying, ie in the ability to deliver max power to the motor with minimum temperature rise.
just got notice of this thread
I use a hyperion charger and I never discharge my lipo's more then 80%,
i asked hyperion this question about their total pack IR measurement:
why changes the internal resistance from 15mOhm when starting the charge slowly to 4mOhm at end of charge , is that normal ?
i got this answer from Hyperion:
IR changing with charge level, higher when a pack is empty (thats why a pack get hot if you discharge too much)
you are saying: IR of a lipo pack is almost independant of charge state
Is the answer of hyperion wrong?
Wayne i've sent you a PM.
Cell resistance measurement is a good thing but to interpret these results
is another thing.
So is there a summary anywhere what could help me to decide if a lipo pack cell is bad or end of life when measuring IR per cell ?
With the hyperion charger EOS0615iDuo3 and hyperion software i make statistics out of the database, and this
is a result of a report i generate out of the database. I use the software only during charging my lipo's.
The IR value is taken from the database at end of charge. ( not the value at the beginning because at charge start IR is higher then at end of charge)
this is one of my reports of my lipo's, do i have healthy lipo's??