Electronic – Battery Charging Current Determination

batteriesbattery-chargingcurrent

When charging a battery using a solar panel, or even another battery, how is the current flowing through the battery determined?

Will the internal resistance of the battery draw a certain amount when drained and decrease/increase as it charges? Or is the current simply determined by the builder using a resistor or other loads with the internal resistance being small enough to negate?

Best Answer

What I have always seen/done is a small-valued resistor (in the range of 0.01-0.05 Ohms; they're called current sense resistors) in between the battery's negative terminal and the system ground. Measuring the voltage at the battery's negative terminal (with respect to system ground) will give you the current flowing into the battery, and you can adjust the applied voltage at the positive terminal to control it.