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Author Topic: Do I have to consider my solar setup when I change the house battery?  (Read 142 times)

richardhufford

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I just purchased a new house battery and it occurred to me that I might need to be more careful installing it than I would with a battery for my car.  The solar controller is on whenever the sun is out, so at the very least letting the positive battery terminal touch the chassis would probably cause a short, even if the negative terminal is disconnected.  Do I need to turn off the solar controller before I change the battery?  Would I do this by pulling the fuse?  Here's are photos of my solar system:  Two are of the controller and one is of the panel on the roof. 
  Another question I have is:  Is this the whole solar charging system, or is there another box somewhere?
Thanks,
Richard Hufford
San Jose, AZ
1991 Thor Establishment M275
1959 Willys Station Wagon

AStravelers

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Re: Do I have to consider my solar setup when I change the house battery?
« Reply #1 on: August 02, 2017, 05:36:48 PM »
A properly installed solar controller should have a fuse or cutoff switch to disconnect the controller from the battery.  Usually external from the controller.

If the 2nd picture is of fuses, the red wires look awfully small to be the main disconnect fuses.  They could be some internal fuses in the controller.

If you can't find a fuse or cutoff switch then when you remove the cables from the battery wrap a small towel or rag around the cable ends so they are well protected from touching the frame of the RV. 

Al & Sharon
2006 Winnebago Sightseer 29R
2009 Chevy Colorado 4X4

http://downtheroadaroundthebend.blogspot.com/

Lou Schneider

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Re: Do I have to consider my solar setup when I change the house battery?
« Reply #2 on: August 02, 2017, 08:44:23 PM »
Don't worry too much about shorting out the solar panel wires. 

If you short a battery, you unleash all of the power stored in it with a large spark and bang.  A shorted solar panel only produces a little spark, whatever power it's producing at that moment, and the short doesn't harm the panel or controller.

In fact, one of the specifications for a solar panel is Short Circuit Current ... how much current the panel delivers into a dead short.

And always when working on a battery, disconnect the negative wires first and reconnect them last.
« Last Edit: August 02, 2017, 08:54:00 PM by Lou Schneider »

richardhufford

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Re: Do I have to consider my solar setup when I change the house battery?
« Reply #3 on: August 05, 2017, 12:03:15 AM »
Thanks.  I successfully replaced the house battery, and I don't think I damaged anything.  I had more trouble with the corroded battery holder than I did with the solar electronics.

After I disconnected the negative terminal, I connected an ammeter from the positive terminal to the frame, and it showed a current of about 1.25 amps.  Then, I thought of the chassis battery, so I disconnected the negative terminal of the chassis battery.  The current from the positive terminal of the house battery to the frame was then about 1.5 amps.  If the batteries are properly isolated, shouldn't I measure the same current, regardless of whether the chassis battery is connected?

I then pulled the fuse to the solar controller, and the current went down to zero.  Then I replaced the battery.
San Jose, AZ
1991 Thor Establishment M275
1959 Willys Station Wagon

 

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