1 Solar panel--2 Seperate batteries

pianotuna wrote:
Since they would be defacto wired in parallel how would they get to different charge levels?

Because the OP said they were separate batteries.

Bruce

Different types of batteries--different ages--widely separated.
I think I'll go with another panel and controller.
Windy Day has a package on ebay--panel, controller, 40 feet of wire and brackets for about $180.
Thanks for the input.

I have two battery banks, one controller, and one solar module. I chose to control the charge current from the solar with a battery master disconnect switch that has options of single bank or both banks charging. The negative phase is tied together with a buss bar in a separate box. I also have the inverter and converter switched in the same manner, that is probably overkill for most but I wanted the options to be available. Most of the time, all of the 12v system is connected in parallel.

Hi,

There are controllers specifically made for motorhomes with a primary and secondary twin outputs. What is does is charge the primary as much as it needs, and once it reaches 13.5 volts, it will charge the second battery until that one is full, then will try filling the first bank until it is at 13.8 volts, or the sun goes down.

If the first battery gets below 12.8 volts, even if the second one is not full, it will charge the first battery. This will work great, if you don't have space for a second panel. Yet as low cost as a 100 watt panel is, it might be best to get an additional panel and a low cost PWM solar controller. This might cost as little as $175 - $200.

SunElec.com is one place to find 12 volt nominal panels that will put out about 21 volts open circuit (when not under a load). This allows the use of a lower cost PWM controller.

I bought a 10 amp PWM solar controller for only $13 from AliExpress.com

I made panel mounts from 2" angle aluminum from Home Depot. Cut into 6" long with 3 holes 3/16" diameter and #10 screws into the roof and 5/16" holes for 1/4" bolts into the panel frames. Plenty of rubber roof sealant completed the installation.

I ran the wiring down the back of my refrigerator. using a coat hanger helps pull the wire all the way down. I was lucky enough to have a closet beside my refrigerator, and that is where I mounted the controller (with display) - the wiring inside the closet, the display on the hallway side of the closet wall.

Remember that a $200 solar system will last about 30 years. So that works out to about $15 a year, much less expensive than the battery it will protect for about 5 years (12 volts) or 10 - 13 years for golf cart batteries. So the solar system will outlast at least 6 12 volt batteries, or 3 or more sets of golf cart batteries.



Good luck with your project.

Fred.

Hi Bruce,

Since they would be defacto wired in parallel how would they get to different charge levels?

I am also assuming identical batteries.

pianotuna wrote:
Hi,

If you are careful to have exactly the same length of wire from the charge controller to each battery it will be ok.

Even if the batteries are at different discharge levels?

Bruce

Take a look at the Susnsaver Duo



Sunsaver Duo

Bruce

Hi,

If you are careful to have exactly the same length of wire from the charge controller to each battery it will be ok.

Consider a combiner such as Trik-L-Start.
Otherwise I would prefer a second panel and controller.

I already have 1 controller and the batteries are 20 feet apart.
I will check the site.