Multi-bank solar battery maintainer

[jeffw]

Hi:

I use our HDT to pull a racing trailer, and with the COVID shutdown, the batteries in the truck and trailer aren't very happy.

I am considering adding a couple of solar panels to keep the batteries topped off. In the truck, I've got the 4 starting batteries, and 4 golf cart batteries for the inverter (so 2 banks).  In the trailer, I've got 2 critical batteries (one for the inside lights and generator starting, and 2nd to power the hydraulic car lift). I've got a 3rd battery in the trailer that powers a small inverter.

Do I need to keep the banks isolated from each other while charging? Is there a multi-bank charger that would do that? If there was such a beast, I was thinking of 2 panels and 2 chargers.

Thanks!

-jeff

[jeffw]

Also, suggestions for solar panels? I've got 2 storage bins on the back of the truck, and I was planning on putting the panels on top of them. The dimensions are 30x55 and 24x60.

Edited June 16, 2020 by jeffw

[Randyretired]

I have a 35 watt solar panel on our HDT and it keeps the batteries charged.  However it depends on the sun available and the load.  For just keeping batteries charged I would imagine a 50 watt solar panel and a cheap controller would work in most places.  I currently have a 50 watt panel on a backhoe with a cheap Renology controller and after a year the batteries test as good as new even after sitting all winter.  If you need to keep batteries that are supplying power such as lighting it is hard to determine solar requirements without determining load.  Panels have come down in price so much that a bigger panel is not a lot more than smaller panels and in this case more doesn't hurt.  As for keeping the batteries connected for charging both at the same time that is tricky.  The resistance in the wires connecting the batteries can result in the distant batteries not fully charged.  If there is not much distance and the wires are good size you might get away with it for just keeping them charged. 

[rpsinc]

3 hours ago, Randyretired said:

I have a 35 watt solar panel on our HDT and it keeps the batteries charged.  However it depends on the sun available and the load.  For just keeping batteries charged I would imagine a 50 watt solar panel and a cheap controller would work in most places.  I currently have a 50 watt panel on a backhoe with a cheap Renology controller and after a year the batteries test as good as new even after sitting all winter.  If you need to keep batteries that are supplying power such as lighting it is hard to determine solar requirements without determining load.  Panels have come down in price so much that a bigger panel is not a lot more than smaller panels and in this case more doesn't hurt.  As for keeping the batteries connected for charging both at the same time that is tricky.  The resistance in the wires connecting the batteries can result in the distant batteries not fully charged.  If there is not much distance and the wires are good size you might get away with it for just keeping them charged. 

I have 2 50W panels that I bought that were pretty cheap and outfitted them with alligator clips.  I move them around to my several trucks when they sit.  I also bought a 20W panel to charge my welder battery because the 3 different rheostats I bought did not fix my lack of charging proble, but with this panel mounted on top of a tool box, no more problems.  Each has a charge controller.  Best approach to battery maintenance I have ever used.