Solar battery maintainer?

[edju]

I'm looking to buy a solar battery charger that will maintain the coach batteries while I'm in storage. I'd like to hear feedback on what you have used and had good results. A charger that will not overcharge and has a good controller. I have two AGM batteries in the coach.

I've also read that I need to keep the chassis battery charged. I think the Trik-L-Start does that. Or maybe I could just add a jumper wire from the coach to the chassis battery when I'm in storage.

Although, I think when I'm hooked up to shore power, the onboard converter (WFCO 8955 I think) only charges the coach/house batteries, not the chassis. It's only when the engine is running that the alternator charges both the chassis and coach batteries. I'd like to get confirmation on that.

I've got a 2018 Sunstar 29VE.

I'd like to hear your experience on both of those topics. Thanks in advance.

[edju]

I've since verified with a voltmeter that when connected to shore power, the coach batteries are charged, but not the chassis battery. However, when the RV engine is running, all batteries are charging via the alternator.

Any comments about a good solar battery charger while in storage would still be helpful. Thanks.

[DavidM]

You will need at least 50 watts to keep up with parasitic loads even with the battery disconnect switch off. Forget tiny 10 watt, no controller panels.

I am a little surprised that the coach won't charge the chassis batteries. Most modern BIMs do that.

So look for a solar controller with two outputs, isolated of course, one output connected to coach, the other to chassis. Epever makes one for about $36 on Amazon: https://www.amazon.com/Controller-In...dDbGljaz10cnVl

I use a 50 watt panel with a 10A PWM controller connected to two AGM batteries. The BIM keeps the chassis batteries charged. I draw about 0.07 amps from the coach batteries with the battery disconnect switch off. The 50 watt panel keeps up fine, but 100 watt panels aren't much more expensive.

David

David

David

[BobC]

I have a similar set up to David's. My MH is older so I installed an Amp-L-Start. My panel is temporarily attached to my ladder since the rear of my MH faces the sun while in storage. I think a 25W panel would be sufficient but I already had a 50W panel from a non-RV project.

[edju]

Originally Posted by BobC

I have a similar set up to David's. My MH is older so I installed an Amp-L-Start. My panel is temporarily attached to my ladder since the rear of my MH faces the sun while in storage. I think a 25W panel would be sufficient but I already had a 50W panel from a non-RV project.

Hi Bob, You said you had a similar set up to Davids. But with the Amp-L-Start, you wouldn't need a dual output charger would you? The 12V supply to charge the coach batteries would be used by the Amp-L-Start to charge the chassis - right?
Thanks for the reply.
Ed

[BobC]

Originally Posted by edju

Hi Bob, You said you had a similar set up to Davids. But with the Amp-L-Start, you wouldn't need a dual output charger would you? The 12V supply to charge the coach batteries would be used by the Amp-L-Start to charge the chassis - right?
Thanks for the reply.
Ed

I didn't read David's comment about a dual bank controller as his having one but as a suggestion in lieu of a modern BIM (Battery Isolation Manager), Amp-L-Start or Trik-L-Start. He wrote:

I use a 50 watt panel with a 10A PWM controller connected to two AGM batteries. The BIM keeps the chassis batteries charged. I draw about 0.07 amps from the coach batteries with the battery disconnect switch off.

This is identical to my setup (with a single output controller) except I don't have a modern BIM like David's to manage things, just a solenoid that kicks in to allow the alternator to charge both the chassis and house batteries. BIM's are bidirectional and allow charging in both direction while managing the connection so that one battery doesn't deplete the other. Because I don't have such a BIM I have an Amp-L-Start.

By the way, you could simply use a jumper but it's not going to manage the connection but I wouldn't advise it. It's never a good idea to simply connect two different battery banks together.

Since your chassis battery aren't charging when the house batteries are charging, I assume that you don't have such a BIM (or, if you do, it's not functioning properly).

With a dual-bank solar controller alone, your chassis battery won't charge when connected to a trickle charger or via your converter/charger when connected to shore power. You'll need the Amp-L-Start for that, in which case you can get by with a one-bank solar controller connected only to your house battery. On the other hand, a dual-bank solar controller and an Amp-L-Start may give you the best of both worlds and won't interfere with each other.




__________________
Bob C
2002 Itasca Suncruiser 35U
Workhorse Chassis