Solar panel install - how to wire to batteries

[Redlightrob]

Hi all,

I have a lovely 2010 15B trailer and am installing an 80W solar panel for my next trip. I don't have a good understanding of how the DC power system works, so my question is this : There are two 12V batteries on the trailer (one inside by the seating and one outside at the front beside the propane tank) : when I am connecting from the solar controller, do I connect the positive to one battery and negative to the second battery, or both leads to the same battery? I am uncertain if I put them to one battery if they will both charge.

Thanks in advance,
Rob

[padlin]

As long as there is no battery selector switch you can connect to either battery to charge both. If you have a switch, it would look similar to this.

[Redlightrob]

Thank you!

[Ron in BC]

I take it that these are two 12V batteries, not the usual two 6V batteries.

I'm a great fan of having two 12V batteries. If that's what you have then a battery selector switch is the way to go. It isolates each battery and pretty much guarantees that you suddenly have no battery power because one is always in reserve.

If they're not the same age and type then charging them separately is the way to go.

If you have two 12V batteries and no switch they must be connected in parallel so it wouldn't matter which positive or negative terminals are used because the connection is positive to positive and negative to negative.

Ron

[Redlightrob]

Thanks, that makes perfect sense (it is two 12 volt batteries).

[ChuckBC]

Originally Posted by padlin

As long as there is no battery selector switch you can connect to either battery to charge both. If you have a switch, it would look similar to this.

Is this a good switch to use? If you switch to Off and solar controller wire is connected won't it damage controller? Shouldn't solar panel to controller be disconnected first?

[padlin]

I think that's dependent on the controller, but I don't have a switch so it's not an issue. I like the Blue Sea products so that's the brand I would use. If I want to kill all 12vdc in my trailer I disconnect the batteries and pull the fuse from the panel, in no special order.

[Vermilye]

Originally Posted by ChuckBC

Is this a good switch to use? If you switch to Off and solar controller wire is connected won't it damage controller? Shouldn't solar panel to controller be disconnected first?

With most controllers operating close to their current limits it is a good idea to turn off the solar input before disconnecting the battery. In the case of 2 12V batteries with a switch to choose between them, I'd install a switch of circuit breaker at the controller input, and disconnect the panels before switching.

[dfandrews]

Originally Posted by padlin

I think that's dependent on the controller, but I don't have a switch so it's not an issue. I like the Blue Sea products so that's the brand I would use. If I want to kill all 12vdc in my trailer I disconnect the batteries and pull the fuse from the panel, in no special order.

I thought you meant Blue Sky products, but checking that out, I find that Blue Sea makes the battery disc. switches.


Blue Sky does, indeed, make solar controllers (like the excellent one we have in our Escape).