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mcmichaelangelo avatar image
mcmichaelangelo asked

Why is my bulk charge voltage so low when PV voltage is high?

I just installed a Victron 100/30 MPPT controller, and am curious why the bulk charge voltage is showing much lower voltage than it "should" show. I have 3 panels wired in series-parallel, and it shows (on this cloudy day) that the panel voltage is 22v, but the bulk charge to batteries is only at 12.74v (instead of 14.6v for the 206Ah lithium battery). I'm hoping this is a noob misunderstanding rather than a hardware issue... Thanks!

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kevgermany answered ·

First thing is to check voltage with a volt meter at MPPT and batteries.

In bulk, voltage is going to be lower than you expect due to battery being partially or fully discharged. Voltage will rise as battery becomes charged.

It would be good to see a screen shot of the voltages and currents as well as the battery settings in the MPPT.

Also what panels are connected?

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mcmichaelangelo avatar image mcmichaelangelo commented ·
Thank you for explaining. That helps. I will check current/voltages when I get a clamp meter after the trip I'm about to take, but I did notice today that as the sun came out and the battery reached a higher SOC (it had gotten down to about 10%) that the voltage increased. It never left Bulk charging. I have two 100w panels in series wired in parallel to a 240w panel. When they were in direct sun today, to data looked about what I thought it should (I know there's a loss with the mismatched panels). Thanks again for your help.
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