Quote:
Originally Posted by mark christopher
Lower ir. Means more punch,
The biggest factor when measuring ir is cell temp, a warm cell will have lower ir, so when comparing chargers your Lipo should be same temp.
I can get my 1s packs around 1ohm, by discharging and charging at 40amp. Only really need low ir in stock racing, off road with mod motors batteries are not the limiting factor
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Are you using an iCharger Mark? Typical pack IR values from my various chargers are in the milliOhm range, not Ohms. However the value does depend on the charger and the IR measurement/calculation process (no industry standard), which is my original point about the actual measured values are a bit meaningless, or not comparable between chargers. You are looking for consistency through the packs life on your charger. When you see the values creeping up, time to replace it.
I think the points above by 5tone are right, charge lead (condition) is important, and battery terminal condition is certainly important influence on the total internal resistance of the system as a whole, both for measurement (consistency) and actual charging.
And most chargers do calculate the IR figures, not measure, which is a complex process to do accurately. The process of trying to measure will change the actual values. Also the "cheaper" chargers do the pack as a whole, not the individual cells within the pack.
And Mark mentions pack temperature is also a fair point. One can play a game of getting the lowest IR of a pack by changing the variables, but it's generally a waste of time and effort, as for a given pack the IR is what it is.