Solar Kit
Just received my kit. 2 100w panels with a 30a pwm controller. Hoping it will recharge my 2 GC2's. I am alone in the trailer and power use is min. Any thoughts?
Forum Discussion
I just bought a Renogy 100W suitcase solar kit. I'm trying to figure out what the effect of the 15ft thin wires between the controller and the battery will be.
I'm seeing about a 0.6 volt difference between the battery and the controller with 3.5 amps flowing. That is a bit more than I expected.
The controller manual describes three modes, "bulk" where all the panel current is passed through to the battery, "boost" where the PWM controller limits current to hold the boost voltage, and float where it holds a lower voltage. Boost mode has a time limit on it, which can be set up to 180 minutes.
I have set the "boost" voltage on the controller to 15. While the battery is low, the controller will just pass through all the panel current. The voltage at the panel will be nearly 1 volt higher than the battery, but the current vs voltage curves for solar panels seem to show that the current doesn't drop much until panel voltage gets over 16, so the voltage drop across the wires won't matter much.
Once the battery gets better charged, the controller will see 15 volts, and start decreasing the current. That will decrease the voltage drop across the wires, so the controller won't need to drop the current much. But the boost phase won't charge as fast as it could, and the 180 minute timer will start prematurely, so it could drop into float mode early.
I don't think I need to worry about over-charging, since this is only a 100W panel, and the kit will only be connected when I am dry camping, so it will always start the day with the batteries a bit down.
I'm seeing about a 0.6 volt difference between the battery and the controller with 3.5 amps flowing. That is a bit more than I expected.
The controller manual describes three modes, "bulk" where all the panel current is passed through to the battery, "boost" where the PWM controller limits current to hold the boost voltage, and float where it holds a lower voltage. Boost mode has a time limit on it, which can be set up to 180 minutes.
I have set the "boost" voltage on the controller to 15. While the battery is low, the controller will just pass through all the panel current. The voltage at the panel will be nearly 1 volt higher than the battery, but the current vs voltage curves for solar panels seem to show that the current doesn't drop much until panel voltage gets over 16, so the voltage drop across the wires won't matter much.
Once the battery gets better charged, the controller will see 15 volts, and start decreasing the current. That will decrease the voltage drop across the wires, so the controller won't need to drop the current much. But the boost phase won't charge as fast as it could, and the 180 minute timer will start prematurely, so it could drop into float mode early.
I don't think I need to worry about over-charging, since this is only a 100W panel, and the kit will only be connected when I am dry camping, so it will always start the day with the batteries a bit down.
