Battery Charge Requirements
Looking into a solar setup for my new trailer, first off is figuring out what I need for controller output to correctly charge my batteries. I'm planning on eventually having a pair of either 100w or ...
Forum Discussion
Padlin wrote:
Then the amperage/current from the panels via the controller slowly raise the battery amperage and as they do the voltage at the battery, which is the same as that felt at the controller output slowly rises?
Er... no.
I am not sure whether the amperage is rising first and then the voltage. When voltage is rising, the current is dropping as the SOC is nearing Bulk setpoint (90%?). Then both voltage and current drop when controller and battery go into Float stage. And, any time when it gets cloudy, the current drops too, of course.
And - no, the battery voltage is not "the same as that felt at the controller output". Cheap controller doesn't know that there exist voltage drop between the controller output and the battery. This drop can be significant when amps are high and cable to battery is long and thin. Better controllers like Rogue MPPT and Tristar MPPT have a separate "voltage sense wire" that tells the controller exact voltage on the battery contacts. With 130W I would get a short and beefy battery cable and ignored the voltage drop. With 260W I would consider voltage sense wire.
