Originally Posted by Rumple
Can I use an old pack to power the meter, and measure the IR of the cells of another pack without issue?
All kelvin type ESR meters will require main leads to be attached to the meter in order to get an accurate measurement of individual cell internal resistance. You could fabricate a special lead that engages the balance connector and use the meter in 'pack' mode. This will give you total pack internal resistance plus resistance of wires and connectors but will not allow for accurate internal resistance measurement of individual cells.
When measuring new packs without connectors, I simply stick some sharp probes into the ends of the wires to simulate a pack connector. This allows true kelvin internal resistance measurement of individual cells without having to add a connector to the pack.