What will I need to use a Solar Panel and Battery Charger/Maintainer together?

[Ironclads]

I currently have two charger/maintainers hooked up to my 2 12volt deep cycle batteries. My batteries seem to discharge when the generator isn't running and nothing is turned on. Is this because of the charger/maintainers, or something else do you think? When my RV generator is running these charger/maintainers both charge and then maintain the batteries. I have a 12V 100 Watt solar panel and a solar charge controller I want to hook up to my deep cycle batteries as well. Do I need anything in between the solar charge controller and the batteries? Is there any switches or other things I need to do so my solar panel can charge the batteries when the generator isn't running, but not be damaged by the charger/maintainers when the generator is running?

Thank you for your help. I much appreciate it.

[NCmountainsOffgrid]

what type of RV do you have? is the generator On-Board, or a separate unit? Why are you using a battery charger, and not your built-in Converter/Charger?

how do you have your two 12v batteries connected to each other, Parallel, or Series?

your 100w panel, with controller, should charge the batteries fine during the day...
any charger used by the generator or shore power shouldn't matter with the solar, the solar controller takes care of that, that's it's job...


2014 Thor Palazzo diesel pusher
Magnum ME-2012 Inverter/Charger
100w/5amp Solar, 20amp PWM controller
50amp Shore Power service

[Ironclads]

Its a 1993 Dutchmen Classic 5th wheel. I've been using the charger/maintainers since I heard that the charger onboard will ruin batteries over time. The batteries are in parallel. So you think I can connect the solar controller directly to the batteries and not worry about anything getting damaged when the generator is on or plugged in? Oh, and the generator is a Champion 3100 30amp separate unit.

[zamboni]

It's not uncommon for RVs to have phantom loads or "energy leaks", even when everything seems turned "off." Newer ones tend to have this more due to the fancy gadgetry, but since your rig has some years on it, there may be a switch or other device gone bad that's allowing the batteries to discharge. Even a small discharge, when it goes on 24/7, can add up to a lot and perhaps be more than your maintainers can compensate for.

If you have a multimeter, try turning everything in the coach "off" (maintainer disconnected) and then measure the current coming out of the batteries. This will require disconnecting one of the battery cables and putting the meter between the battery and the cable - don't forget to plug the meter's probes into the correct ports or you'll smoke it : ). If the meter reads anything other than zero you have a phantom load to chase down. If you don't have a multimeter...they're really cheap and super useful, you should be able to get a simple one under $20.

BTW you say your batteries "seem to discharge". What specifically are you observing that makes you say this? How old are the batteries?

- Jerud
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1220W array / 1000Ah LFP house bank
MidniteSolar Classic 150, Magnum MS2812
ME-RC, Trimetric, and JLD404
Full-time 100% electric boondocking (no propane, no genny) since 2015
2001 Fleetwood Prowler 5th wheel 25 foot, self-rebuilt
www.livesmallridefree.com

[Ironclads]

I've used my voltage meter, but I'm not sure how to do what you suggest. Here's my meter: https://www.radioshack.com/products/...tal-multimeter Would this meter be able to test to see load? they are new batteries, less than a year old. If I can't track down the issue, I may just install a switch at the batteries so things are definitely off to the rv when not in use. Thank you for your help and suggestions thus far. Much appreciated.

[SunEagle]

I've used my voltage meter, but I'm not sure how to do what you suggest. Here's my meter: https://www.radioshack.com/products/...tal-multimeter Would this meter be able to test to see load? they are new batteries, less than a year old. If I can't track down the issue, I may just install a switch at the batteries so things are definitely off to the rv when not in use. Thank you for your help and suggestions thus far. Much appreciated.

Most RV's already have a battery disconnect switch which will remove any and all loads from the DC system when it is not in use. Those switches were installed that way so you can store your RV for a while and not come back to dead batteries.

[zamboni]

Ironclads, that meter is rated to 200mA max, which is not very much current (0.2A). If you do have a phantom load, there is a possibility it is larger than 0.2A, and might blow the fuse in your meter. At least you'd know there was a leak, but you'd have to open up the meter and replace the fuse before you could proceed to find the cause of the drain. Of course, it is also possible there is no leak or it's smaller than 0.2A in which case nothing bad will happen. It's kinda your call. Personally i'd look for a meter that can do 10A, which is pretty common even for inexpensive pocket meters.You can probably get something for under $20 on Amazon. I hate telling people to go out and buy stuff, but a more capable meter isn't a bad idea. You can leave the old one in the truck for checking the starting battery.

My rig is a 2001 and had no main disconnect...and even if it did, i wouldn't trust RV manufacturers to actually put it upstream of everything. This could be an actual safety feature -- two of the most common phantom loads i've heard people mention are CO2 alarms and breakaway switches. I wouldn't be surprised in both cases if those devices are wired upstream of a "main disconnect". The CO2 alarm obviously stays on 24/7 by design, and breakaway switches are very rudimentary devices which could fail closed.

[bcroe]

I prefer to insert a small (193, etc) 12V bulb between the battery + and its disconnected + cable.
In case of a larger current, nothing will be damaged. If the bulb does not light at all, put your
DVM across it and see if there are any measurable millivolts. Bruce Roe