I connected my pack in series and performed a crude load test and a rough calculation of internal resistance under load. I didn't have my BMS connected yet, but I hooked up my 2000W inverter and ran a 1500W hair dryer. The front panel of the inverter and my kill-a-watt meter were both reading about 1.54 kW, and my pack voltage sagged from 26.0 volts down to 25.6 volts. I calculate the internal resistance of the pack around 6.2 milliohms. At first I was crestfallen as I thought it should be somewhere in the vicinity of 1 milliohm. Then I remembered I had 8 cells in series, so my internal resistance per cell is around 0.8 milliohms, which is a bit lower than the vendor measured, but still higher than spec. Assuming it holds up at my inverter's maximum load of 2000W, the largest voltage sag I should see is about 0.5 volts. But for my main application - running two freezers which each pull 120watts each when compressors are on, plus a surge whenever the compressors are starting up, I think I will be fine for now. But I recognize that this is probably as good as it gets, and I should monitor internal resistance as my pack ages. I also checked the voltage of each individual cell while under the 1.5 kW load, and they were all very close to equal so that indicates the internal resistance of all the cells are close to the same. Quiescent current of my Giandel 24V 2000W pure sine inverter is 0.7 Amps, so I'm reasonably happy with that. I didn't run the hair dryer longer for a few minutes, but I didn't notice any of my connections or inverter cables getting warm so that is good. I didn't bump it up to 2000W load because I'm using the cables it came with that I think are about 6AWG, and I have some 2AWG cables on order, but not here yet. I want to wait until I have all the connections the way I want them before I do a max load test.