Resistance is Futile.
Can someone that's in the Battery business quantify for me with numbers the type and measurement of Wet Cell lead acid battery recharging resistance, for the various types... sealed, AGM, etc. I am...
Forum Discussion
I've been measuring battery resistance for years. It's not that difficult. You'll need an amp meter and voltmeter.
1. Measure charging current into the battery (I_1) and voltage at the battery (V_1).
2. Turn on a load that's about I_1/2. (Half of I_1)
3. Immediately measure battery current (I_2) and voltage (V_2).
4. Calculate battery resistance: R_bat = V_1 - V_2 / I_1 - I_2
Run the test a few times to get consistent results. You can also do the test going from 1/2 current to full current. Results should be the same.
Resistance is dependent on SOC. It increases above 75% SOC.
A LA battery could have about 12 mohm resistance. AGM have about 1/2 that amount.
Two batteries in parallel will give you half the resistance of one battery.
Sal
1. Measure charging current into the battery (I_1) and voltage at the battery (V_1).
2. Turn on a load that's about I_1/2. (Half of I_1)
3. Immediately measure battery current (I_2) and voltage (V_2).
4. Calculate battery resistance: R_bat = V_1 - V_2 / I_1 - I_2
Run the test a few times to get consistent results. You can also do the test going from 1/2 current to full current. Results should be the same.
Resistance is dependent on SOC. It increases above 75% SOC.
A LA battery could have about 12 mohm resistance. AGM have about 1/2 that amount.
Two batteries in parallel will give you half the resistance of one battery.
Sal
