Yes, as john61ct mentioned, tracing of the internal resistance is useful, however requires using still the same conditions (temperature, SOC) and method. Using precise equipment is a must.
2,81 probably means miliohms, 20p LG HG2 should have about 1 miliohm per one paralel group (new fresh cells). Values 0,8 – 0,9 are telling us that inaccuracy of this BMS measurement was 10 – 20 %.
If you want to copy resistor method from video, you need to get at least 1A per cell which is 20A total. 4 V per cell means 56 V total for 14s battery. To get 20 A you need precise resistor 2,8 Ohm, power dissipated on resistor would be 1 120 W !!! Moreover, as temperature of the resistor will go up, the resistance will go up also and real current will be smaller. That is one reason of inaccuracy on the video, unsufficient DMM resolution is another, unsufficient resistor accuracy another, ………
As 1 kW precise cooled resistor is little bit a problem, I suggested method of cell´s voltage difference measurement during charging. I assume that charging current is about 1A per cell.
Resulting accuracy will depends on the current measurement accuracy and voltmeter resolution.
Even if total inaccuracy will be suppose 10 – 20 %, for checking of sudden 300 % rise of IR measurement such method could be sufficient.
Maybe you can borrow DMM with enough resolution and clamp meter or precise shunt for current mesurement.
