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
Hi,
Let us suppose the battery voltage is 11.7 (god forbid). If you attach a PWM charge controller the voltage will appear to be 11.7, at least initially. As the battery charges the voltage will rise.
Once the battery bank is 90% charged then the voltage will be say (this is hypothetical and a guess) 13.2. Eventually when the bank is 99% that will rise. Probably the charge controller at that point will scale back the voltage (if it is a good one).
My original solar system on a previous RV had an old shunt type controller. When the voltage got high enough it would turn on and off.
MPPT works a little differently--depending on where you are in the state of charge.
260 watts of solar is going to be enough to do a GREAT job on the batteries--but don't "cheap out" on the controller. Buy a quality unit. PWM will do a good job for you.
At 130 watts I'd wish to see you use an MPPT controller. I'd also prefer to see 140 watts instead of 130.
On my first solar system I had just 30 watts to maintain 250 amp-hours of battery bank. It worked well, because it was several weeks between trips and the solar had enough time to "top charge" the battery bank. I did not buy it--but that 30 watt system cost $1400.00.
Let us suppose the battery voltage is 11.7 (god forbid). If you attach a PWM charge controller the voltage will appear to be 11.7, at least initially. As the battery charges the voltage will rise.
Once the battery bank is 90% charged then the voltage will be say (this is hypothetical and a guess) 13.2. Eventually when the bank is 99% that will rise. Probably the charge controller at that point will scale back the voltage (if it is a good one).
My original solar system on a previous RV had an old shunt type controller. When the voltage got high enough it would turn on and off.
MPPT works a little differently--depending on where you are in the state of charge.
260 watts of solar is going to be enough to do a GREAT job on the batteries--but don't "cheap out" on the controller. Buy a quality unit. PWM will do a good job for you.
At 130 watts I'd wish to see you use an MPPT controller. I'd also prefer to see 140 watts instead of 130.
On my first solar system I had just 30 watts to maintain 250 amp-hours of battery bank. It worked well, because it was several weeks between trips and the solar had enough time to "top charge" the battery bank. I did not buy it--but that 30 watt system cost $1400.00.
Padlin wrote:pianotuna wrote:
Hi,
PWM controllers operate at the battery voltage.
Pianotuna, I don't understand the 2nd part of this response, please elaborate. Looked like you set the controller for the type of battery which then uses the applicable settings. On some you can choose custom setting and set them to whatever you want up to the units max.
I am planning on just one panel to start and will see how it works out, we're not heavy consumers so hopefully one is enough. One panel that fits (narrow), would be either 100 or 130w's. Still have to measure for length.
