Voltage discrepancy- big swings under and over battery voltage

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cousinlarry asked Dec 17, '22

Voltage discrepancy- big swings under and over battery voltage

I have a smart shunt and a smart solar. The shunt seems to be reporting the correct voltage, but the smartsolar is all over the shop- during the day it’s saying the battery is 14+ and at night 8 volts. The battery voltage, according to the smartsolar, is always out of range to charge- so it never charges the battery from solar even though panel voltage is 60+. Here’s some screenshots https://imgur.com/a/jI7AhKu

Why would there be such a wide discrpancy? I’m camping right now and this is the first time I’ve seen it, going to get a multimeter today and test.

voltage

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Answer 1 · 2022-12-17T21:36:01Z

wkirby answered · Dec 17, 2022 at 09:36 PM

I presume that the MPPT absorb Voltage is set 14.3V?
With MPPT reaching absorb Voltage with zero current and zero yield today I'd immediately think that the MPPT is disconnected from the battery for some reason. Check connections and fuses or circuit breakers / fuses between the battery and the MPPT.

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Answer 2 · 2023-01-08T10:25:05Z

cousinlarry answered · Jan 08, 2023 at 10:25 AM

In the end a fuse had blown between the battery and the smartsolar. The erroneous voltage reading on the smartsolar was a red herring… I wonder why any voltage is listed if the battery is not connected?

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