Read Battery Charger status from a device.

[dirtbikerxz]

Originally Posted by Daniel_LaFleur

If the charger is on, and charging the battery, you will get the voltage of the charger.

If it's an intelligent charger, then it will depend on the 'state' of the charger.

If I'm using the frc charger (which is "smart" i believe : http://www.andymark.com/Battery-Char...-p/am-2026.htm)

would I just be reading the volts of the battery after the charger stops charging it?

[GeeTwo]

In order to know the "battery voltage" while actively charging, you will need to measure the charging current I_c as well as the terminal voltage V_t, and have a good idea of the "internal resistance" of the battery, R_i. Then, V_batt ≈ V_t - I_cR_i. Ideally, you'd measure R_i
yourself, but if you just want a nominal value, a study by team 1640 a few years ago indicated that a good FRC battery has an internal resistance of about 0.02Ω. Alternately, if you use a 2A trickle charger, the difference would only be about 0.04V, even when still charging at full current.