question

Thorsten Koch avatar image
Thorsten Koch asked

2 batteries on a boat with MPPT 75/15 and a 150W solar panel

How to best connect 2 batteries on a boat with 12v auto charger in the game and battery switch (1,2, 1&2 and off). Guess I will need some sort of a relay or diode?


Thanks for any hint.

MPPT Controllers
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Thorsten Koch avatar image Thorsten Koch commented ·

OK, sounds like easy to do, I was planing to put a relay in so either the solar or the automatic charger is connected so I would not have voltage on the cable outside if the Solar is not connected and the charger is plugged in or the batteries are on.


Thanks

Thorsten

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JohnC avatar image JohnC ♦ Thorsten Koch commented ·

Yeh, Your solar panel cables 'outside' will always have V on them under sunlight even if not producing. No current will feedback through the mppt, so it's not as though you have batt power (amps) available there.

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Thorsten Koch avatar image Thorsten Koch JohnC ♦ commented ·

Well... I plan to make the Solar "removable" as I plan to put it on the Bimini in Spain. Thought it might be good to be prepared for a removabel option mounting with Loox buttons. Was thinking about a battery separation relay as well but getting that this might be over the top having the battery selector already in place.

Thanks for your hints.

Thorsten

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1 Answer
JohnC avatar image
JohnC answered ·

Hi Thorsten. You could just parallel in the mppt to the autocharger outputs. They'll each control their output by V, and if you want solar to take priority, just back off the autocharger V-settings (if you can) to a little lower than the mppt's.

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