Community Forums

Minnesota51 · 01-01-2022, 12:50 PM

I want to use a solar charger to maintain both my house batteries and the chassis battery.

All three are next to each other under the steps.

I have a knife disconnect switch on the chassis battery.

I have a 50-watt solar panel charger to hook up.

Do I close the knife switch and then attach the charger clamps to the two chassis battery terminals?

Do I leave the knife switch open and attach to just the two terminals of the chassis battery? That's the main one I want to keep charged.

Or do I somehow attach to the far end of the house batteries and the chassis battery?

Thanks!

hclarkx · 01-01-2022, 01:02 PM

Assuming all of the batteries are lead-acid, I would connect them via the knife switch and connect the 50W solar leads to either battery. This is assuming both batteries are fairly well charged to start with. Otherwise, if one is low and the other is high, you might get quite a surge of current as you close the knife switch. If they aren't already well charged, it would be best to charge them individually to full before closing the knife switch.

vicwhit · 01-02-2022, 09:59 AM

I was like you last year. I had connected the house and chassis batteries in parallel and turned off the disconnect switch. It was a great plan to keep the batteries top up over the winter and ready for spring.

Then...the solar charge controlled failed and I ended up with solid state batteries. Solid ice that is. Either parasitic load from the coach or the failed charge controller drained the batteries. Without a charge, the batteries are vulnerable to freezing.

This year I charged them all up, disconnected the cables to the batteries, and rested in peace. That is what I did every year with my boat and never had any problems in the spring.

Crasher · 01-02-2022, 12:35 PM

To be safe and still use your solar panel, I would disconnect the positive cable of each battery bank. If fully charged when put in storage, they should be fine for several months. As added benefit, hook the solar up to the chassis battery for a month and then switch to the house battery bank for a month with the knife switch open. This would prevent one bad battery from draining the others. In the spring you should have two nearly full charged battery banks to start your season.

twinboat · 01-02-2022, 01:19 PM

He never said he had a knife switch between the batteries.
He said the chassis battery had a knife switch.

If you want to keep them a on solar charging, open the knife switch and the house battery disconnect and then connect the solar to the house battery positive and negative. Then get a 10 guage jumper wire to connect the house positive to the chassis positive. The negatives are already connected thru the chassis grounds.

Iceclimber · 01-02-2022, 04:34 PM

I didn't catch if the OP has a controller. I would not leave a solar panel hooked direct to batteries, even 50 watts.

hoggem · 01-04-2022, 10:45 AM

I am solar electric ignorant but would like to hook up a solar charger to by batteries? I have two house and one chassis battery with two rotary off on switches located in a basement compartment.

Looking for a simple easy setup, what should I purchase and how do I hook it up?

vito.a · 01-04-2022, 01:50 PM

Be careful not to confuse watts with amps.
Depending on your parasitic draw, a 50w solar panel may not be enough to maintain three batteries. A 50w solar panel may only produce 3 1/2 amps at solar noon on a clear day. The rest of the day you may only get 1 to 2 amps and of course nothing during the evening.
You also have to allow for shorter winter days as well as clouds.

DavidEM · 01-04-2022, 02:19 PM

Deleted- duplicate

DavidEM · 01-04-2022, 02:19 PM

Quote:

Originally Posted by vito.a

Be careful not to confuse watts with amps.
Depending on your parasitic draw, a 50w solar panel may not be enough to maintain three batteries. A 50w solar panel may only produce 3 1/2 amps at solar noon on a clear day. The rest of the day you may only get 1 to 2 amps and of course nothing during the evening.
You also have to allow for shorter winter days as well as clouds.

I use a 50 watt panel mounted on the south facing bumper in parallel with a 100 watt panel on the roof. The roof mounted panel often gets covered with snow but the 50 watt panel is nearly vertical and plenty to keep two 100 Ah coach batteries and the chassis batteries fully charged. I usually see 13.2-13.5 volts on both battery systems.

I have measured the parasitic draw on my coach batteries with the battery disconnect switch off. It measures about 0.08 amp or about 2 amp hours daily. The 50 watt panel covers that loss just fine.

David