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tofuricer

House battery only charged when it rains

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I bought my toy home just a few months ago.  On my maiden voyage of 9k miles I ran into a ton of electrical challenges, including some battery issues. The previous owner had installed 3 80kW solar panels and a brand-new battery which worked great at keeping the house battery charged prior to setting out on the trip.  Yay for boondocking!   But when the temperatures started dropping in Missouri, the furnace fan would suck down the coach battery power.  Then the battery didn't have enough juice to start the furnace leaving the home uncomfortably cold.  I thought about adding another battery, but my instinct was that something was wrong.  

It wasn't immediately obvious, but I realized the isolator wasn't working.  So I rigged up a little jumper to power both batteries from the alternator while driving.  This got me comfortably through he rest of the trip and back home. 

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When I could receive a delivery, I ordered a new Tekonsha 7000 12 Volt 3 Terminal Battery Isolator and installed it.  A few days later I was trying to blow out the water lines in prep for winter using a compressor running off the house battery, but battery was dead despite 100 miles driven in the last 2 days.  

So I realized the new isolator wasn't working.  After a little diagnostics with a multi-meter, the ignition input wire to the solenoid wasn't working.  So I traced out that the wire was connected to a wire going to the windshield wiper motor.  I immediately thought "Hmm, I'm not sure that will work."  So I just turned on the wipers and voila!  The isolator works!

I now I have a spare isolator. And I realize my jumper solution probably put a ton of wear on the hood latch from opening the hood to connect and disconnect the jumper, every time I started or stopped the car for the majority of the trip... Oh well.

I am now wondering if this simple mistaken wiring job is what caused the previous owner to add solar and the new battery, in the first place.  Either way, glad to know all I need to do is drive in the rain so my house battery will be charged! ;-)

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Could be a DPO (Dumb Previous Owner) screw-up or might even have been done by a DFW (Dumb Factory Worker)! But at least the SCOWM (Smart Current Owner With Multimeter) has got it figured out! :)

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I think the 12v for the wiper motor is a common feed point for the isolator. But it should be on the switch input or see if you can find the park wire for the motor. It should have 12v with the wipers off.  P.S. make sure it also got 12v with the wiper on.

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Yeah it's a screw up with the wires, that is a common place to power the relay but it needs to be the proper wire or it won't work well. Should come on with the key on nothing else charging you battery in the rain only probably won't give you the best results.

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This sounds all to interesting.  I added a couple of Coast Guard surplus solar panels to my '90 Warrior a couple of years ago.  I was never quite sure that they was working until this summer in Newfoundland. A couple of cool nights in the deep woods (running the furnace, and not in the full sun) left me with a drained house battery.  I did some investigating and discovered that I was getting no charge off the engine.  I assumed the isolator failed. When I got back into the sunshine for a day the battery recovered and the crisis had passed.  The isolator had worked fine before the solar panels. And, I have no idea when it failed. It could have been years ago, or the day before in noticed the problem.  Is it possible that solar charge caused the failure? I intended to replace the isolator in the off season, but now I'm wondering if something else is going on. Any thoughts?

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Make sure your panels have  blocking diodes. Being surplus it's possible they were in the wiring and not the panel without them them will backfeed in the dark. Diodes can be installed in the wiring after the fact but if they are not there it will discharge the battery.

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