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Paul Carmichael avatar image
Paul Carmichael asked

MPPT dropping into float

I have 2 150/60s and they've been working for years. The panels are on different elevations but split evenly between banks. Yesterday both mppts produced around 17kWh each. Today one of them has been in float all day and the battery is at a reported 85%. The voltage is showing at 48.xx whilst a multimeter shows 52 at both mppts. Tha panels are all a bit grubby with dust, but not obscured. Last night I had the mains connected to top up the batteries, so this morning the ccgx showed 100%. It's been a gloriously sunny day and the batteries have been slowly discharging all day. Is this a known issue? They are both running software 4.2.

mppt charging
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Paul Carmichael avatar image Paul Carmichael commented ·

I just disconnected the pv cable for about 2 minutes and the charger stayed in float mode.

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2 Answers
Matthias Lange - DE avatar image
Matthias Lange - DE answered ·

If the voltage at the MPPTs is much higher than at the battery you should take a look at the fuses/switches between the MPPTs and the battery.

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Mark avatar image
Mark answered ·

When you disconnect PV (ideally from a circuit breaker after the MPPT charger has been disabled using the switch in VictronConnect), what does the MPPT read as the PV voltage - is it ~0V? (Alternatively you can just check it at night...)

If the PV voltage is not ~0V in this state then the MPPT may have developed an internal short circuit, leaking battery voltage into the PV side and preventing a 'new day' (new charge cycle) from starting.

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