Electronics > Power/Renewable Energy/EV's

Battery internal resistance. Its truthful science knowledge

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What is it all about on NiCd recharge battery internal resistance (BIR), as its knowledge on

roughly tell this mind-confusing one which has at least 7.7 ohm BIR due to MM tested it 1.53 V  0.17 A
how to reduce or "dissolve" this BIR

Siwastaja:
I can't understand the Quora post.

For equivalent DC resistance, "dynamic resistance" is easiest to measure, and offers useful real-life number which you can then use to estimate voltage drop with given current, and heat dissipation in the cell.

Use two dummy loads of different resistances, which are significantly different. For example, if you have a cell with maximum rated discharge current of, say, 1A, you could use dummy loads of around 0.1A and 0.5A.

Connecting the first dummy load, keep it connected for at least 10-20 seconds, then read test current I1 and cell voltage V1.

Then,
Rdc = dV / dI = (V2 - V1) / (I2 - I1)

If the loads are connected for too long, the cell discharges during test, causing an error. You can significantly reduce this error by measuring the first dummy load again (i.e.: sequence of loads: 1 - 2 - 1), and use the averages of the two measurements for V1, I1.

mag_therm:
NiCd..
Here is a good report of hands on impedance test back in their day.