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captenaj avatar image
captenaj asked

Hook up second controller/panel? Do they have to be set to tandem?

Hello all and thank you in advance.

I have a teardrop trailer that came with a 100W solar panel and the Victron MPPT 75/10 controller. I would like to add a 2nd panel so I can chase the sun. I am thinking of the Renogy 100W (or maybe 200W) suitcase panel which comes with the Voyager 20A PWM controller. The Renogy folks say I cannot clip the second panel to the battery because the controllers will think the battery is fully charged and shut off, but it may work if one of them is set to tandem. The Voyager cannot be set to tandem. Do I have to (can I) set my Victron controller to tandem? Can I just clip my Renogy panel to the battery posts? Are there any other settings to consider? I am very afraid of over charging my battery - is this a realistic fear?

Thank you very much for any help!

charge controller compatibility
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1 Answer
kevgermany avatar image
kevgermany answered ·

There's no tandem setting on the Victron. It will charge until the battery is full.

You can use multiple Victron controllers on the same battery without special settings.

No idea about non-Victron equipment.

Overcharging - good chargers use battery voltage to control charging. So charge current is the concern. A reasonable max charge rate is C5, in other words charge at the rate which will completely charge your battery in 5 hours. For example if you have a 100Ah battery, max charge is 100/5=20A. A 100W panel will give a max current of about 8A, usually less in practice.





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