solar panel hooked directly to battery
I've heard of some folks hooking a small solar panel directly to the battery to charge or maintain it. But some panels (my 70W, for instance) can peak its output as high as 17V. My question is, how ...
Forum Discussion
pianotuna wrote:
Hi,
The controller doesn't "knock down" the voltage when the battery is empty.
Well, I realize there are different controllers out there and they may work in different ways. But my Morningstar SG-4 has a stated PWM setpoint of 14.1V, so doesn't this mean that if the panel is sending higher voltage than 14.1, the SG-4 is reducing the voltage to 14.1? I'd read somewhere that MPPT controllers also reduce the voltage, but they somehow manage to send the same wattage and convert that extra voltage into more current (V*A=W so less volts means more Amps). And I thought I'd read a comment at one time that said a PWM controller loses (wastes?) this extra voltage when it steps the voltage down. This is partly why I was wondering if 17V can somehow push the charge into the battery faster than 14.1V would. Not that I'm planning to do it; like I said, it's academic... I'm curious to know how it works.
