Solar charging

[jay see]

Question for the knowledgeable.

I'm using a double Anderson from the aux battery to 1. Power the fridge in the back and 2. Adding a folding solar panel when needed. Is there any issues in doing this.

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[Cuppa]

If I have understood correctly - you currently have aux under the bonnet connected to the crank batt via VSR or dc to dc charger? Cable to Anderson plug to power the fridge.

And you just want to use another anderson to connect the portable solar panel direct to the aux battery when you pull up at camp.?

If so I don't see a problem.

Main consideration is that you have sufficiently heavy cable to minimise voltage drop from aux battery to fridge. (Most fridge problems are caused by cable being too thin). More important with the solar than with alternator charging. With fridge running measure voltage across terminals of aux battery. Then measure voltage at fridge. If Voltage at fridge is say, more than 3% less at the fridge then the cabling between them needs upgrading. eg. 12.8v at battery & 12.45 at fridge with the fridge running is as marginal as you would want to go.

Just another thing - most folding panels come with a regulator attached to the rear of a panel. Not ideal. Better close to the battery. It makes a difference. And usually the cables supplied with panels is too light. Address these two issues & you will get more out of your panel into the battery, rather than lost in the cable.

[jay see]

I have my aux battery behind the rear seat and a double Anderson coming off that. I'm using a redarc sbi12d (dual sensing isolator). I have recently mounted a fixed 110w panel which has a mppt regulator mounted to the board, close to the battery. If I plug in my folding panel for an extended stay I should be good??


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[Cuppa]

Might not be a good idea to use two different solar regulators. Better to have a single regulator on the board close to the battery. If the one you have there at psent doesn't have enough current capacity to use with both solar panels I think you should upgrade it.

It won't do any harm to try with two regulators but I have heard stories of folk doing this & wondering why the additional panel is not making any difference, only to discover that one was reading the output of the other & 'thought' the battery was charged. I haven't tried it myself & results may vary with different regulators, but as a general rule I'd say 2 'competing' regs is not the way to go.

If down the track you need to do any fault finding, a single reg will make that easier than with two.

A Redarc SBi12D is a VSR (Voltage Sensing relay). Basically a means of ensuring you don't accidentally flatten your crank battery when running your fridge when not driving. the D version also allows the solar power to charge the crank battery when the aux battery is fully, (or close to fully) charged. You may already know that, but I've added it because some mistakenly think that a VSR is a charger.