Adding Solar - is there conflict with shore power transformer? - Fiberglass RV
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Old 07-07-2020, 12:50 PM   #1
Nik
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Adding Solar - is there conflict with shore power transformer?

I have secured a 200w PV panel to my roof. I can tunnel down to the "fuse box" where there is also a transformer and some kind of onboard factory trickle charger. I have a quality charge controller and inline fuse.

What about competing charging systems?

1. Is there a conflict between the on board transformer supplying a charge to the batteries and the solar system doing the same - at the same time?

2. What about the tow vehicle battery? The truck alternator usually charges the house batteries, too. Will that system conflict with the solar or will the solar charge the truck battery?

I've been told to install a switch to shut off the solar when I'm plugged into shore power. (I'll forget, does it matter if I forget?)


I know I can isolate the truck battery from the trailer. Mostly I unplug when camping.

I've read some books and online and somehow this question is just overlooked. Perhaps I'm thinking too much. Maybe just hook it up and go and there's no problem!?

Thanks in advance.
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Old 07-07-2020, 01:01 PM   #2
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I'm assuming you have a solar charge controller hooked up to your panels. If you don't, get one. Connecting panels directly to the battery can overcharge the battery. I have run both a solar charge controller and an AC charger at the same time with no apparent ill effects.
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Old 07-07-2020, 01:14 PM   #3
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Yes, thank you. I edited my post to say I have a full solar system with charge controller. Thanks.
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Old 07-07-2020, 01:22 PM   #4
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Cool! I also forgot to mention that I have plugged the seven way in with the car running and the solar controller connected and have not had an issue. Sometimes I camp where everything is partially shaded so I use my tow vehicle to put some extra juice in the battery.
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Old 07-07-2020, 01:40 PM   #5
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Technically both the charge controller and power center charger should be sensing the state of the battery and choosing their state accordingly, so if they're both functional (not a given with old camper chargers), they shouldn't do any damage.
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Old 07-08-2020, 01:05 PM   #6
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I've been running such a system for four years and not had a problem.
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Old 07-18-2020, 02:44 AM   #7
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Generally you can treat the 12V system like one big bus with power simultaneously going in and out from various places without any problems. It's possible you'll make suboptimal use of the solar if it detects the shore charger and backs off to float mode instead of running in bulk, but that's about the worst-case scenario. Maybe if you have a really small battery and the combined solar/vehicle/converter current's too high, but at least one of them's going to see the higher voltage and back off.

I would not shut off the solar while plugged in. In addition to being unnecessary, disconnecting the controller<->battery connection while panels are still connected to the controller can damage at least some controllers.
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Old 07-25-2020, 04:20 AM   #8
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I recently installed an InteliPower converter-charger and asked the factory the same question. They indicated to connect the solar panel controller Directly To The Battery and NOT to the converter-charger panel. All your electrical sources need internal controllers to sense battery conditions to prevent overcharging. I actually turn my converter-charger Off when boondocking on Solar to lower any amp draws. I usually need to charge batteries once a week on generator without adequate sun. The only caution is your vehicle alternator connection. Your trailer Can and Will draw down your Start Battery to the same voltage.
Either disconnect the trailer-vehicle or install an ignition auto-disconnect solenoid to avoid a Dead Start Battery !
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Old 07-25-2020, 10:16 AM   #9
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Quote:
Originally Posted by CHICO DAN View Post
I recently installed an InteliPower converter-charger and asked the factory the same question. They indicated to connect the solar panel controller Directly To The Battery and NOT to the converter-charger panel. All your electrical sources need internal controllers to sense battery conditions to prevent overcharging. I actually turn my converter-charger Off when boondocking on Solar to lower any amp draws. I usually need to charge batteries once a week on generator without adequate sun. The only caution is your vehicle alternator connection. Your trailer Can and Will draw down your Start Battery to the same voltage.
Either disconnect the trailer-vehicle or install an ignition auto-disconnect solenoid to avoid a Dead Start Battery !
👍 👍 👍

Perry
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Old 07-25-2020, 09:20 PM   #10
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Charging from vehicle

Most newer vehicles have a relay that shuts off charge to the trailer battery line. You can check that with a voltmeter connected to the battery in the trailer. First check voltage with tow vehicle running, then turn it off.
Should be 13.5v running then 12.6v off. (approximate)
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Old 07-26-2020, 12:57 PM   #11
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the solar wiring hooks directly to the battery. The positive wire has its own fuse. It never connects into the wiring for the power converter.



Go to a marine supply store. You can get a fitting that goes onto the battery positive battery lug that provides a place to attach and fuse the positive wire from the solar.
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