Portable Solar Panels

Ninerbikes wrote:
For those that have gone with simple charging panels or with a PWM Controller for their 12V solar panels, what kind of amps, and what kind of voltages do you see with the battery charging up from the solar panels. And how do you know, voltage wise and amp wise, when your battery is 100% topped off with a PWM charger run off a solar panel?

I'm currently running a 120 watt portable solar panel.. about 7 amps at 18.1 V at max V and max amp... battery is a group 24 DC with about 75 AH rated at 20 hours, closer to 100 hou at 1 amp/hour. Something tells me I should keep my usage under 37.5 amps for the whole evening and night, with all parasitic and normal use losss.

The output power values you listed are the mfg.'s ratings, correct? You will probably never see that output in real-world use. The controller will also limit the power harvested, they all have some loss.

The amount of charge needed will depend on what the SOC is of the battery when starting charge. 50% SOC is the bellwether discharge mark, less discharge will increase the number of cycles in the battery's life.

To accurately measure charge in the battery, you'll need either a hydrometer, a battery monitor, or a meter. If you have all three, you'll get darn close.

One observation: having more battery capacity is better, you can get less stingy with use and you'll be able to run more devices in the future.