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marius123 avatar image
marius123 asked

MPPT 75/15 shows wrong Voltage

Everything worked perfectly fine for a quite a while but suddenly the solar charger shows a voltage that's not accurate. It is still charging though.

SmartSolar detects 12,95V battery voltage at night, so it's only the battery voltage, no charging voltage (Standard AGM).

A reliable multimeter shows 12,72V measured directly at the connection screws of the solar charger, so it cannot be some corrupt cable or anything.

The 20A fuse is fine.

Load output works fine.

I don't know whether there was any firmware update before the problem started, earlier this year everything was fine. Firmware is v1.59 now.


I could just modify the charging parameters accordingly, but that doesn't seem to be the best solution.

battery system voltage
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Wayne avatar image Wayne commented ·
@Marius123 so are you questioning the differential between 12.95 and 12.72?
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marius123 avatar image marius123 Wayne commented ·
Indeed. Because the charger detects a wrong Voltage it is presumably also setting wrong voltages for charging. I also measured the battery while it was disconnected: 12,72V, connected to 75/15: 12,72 at battery and the screws at the chargers connection terminal. Still, via Bluetooth it gives +0,3V. This is also true when the battery is charged externally.
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rin67630 avatar image rin67630 marius123 commented ·

I can confirm, here too.

I have exactly the same behaviour.

LiFePo Battery voltage is 13,33 V (shown on the multimeter at Victron's terminals and the battery's BMS identically) and VictronConnect and Victron VE are both showing 14,18V.
And the Victron device stops charging.

Device is set to Smart Lithium LiFePo4 preset
Firmware is current V1.6.3

There is definitely a bug in that device.


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1 Answer
Paul B avatar image
Paul B answered ·

Please provide some screen shots of the displays and the multi meter. the difference may also just be your multi meter as well - also please send screen shots of the MPPT voltage setup pages

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rin67630 avatar image rin67630 commented ·

I have exactly the same behaviour.

LiFePo Battery voltage is 13,33 V (shown on the multimeter and the battery's BMS identically) and VictronConnect and Victron VE are both showing 14,18V.

Firmware is current V1.6.3


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