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Was working fine , but my multiplus ll 48/5000/70 pushed up the voltage too high while charging off the generator, despite my best efforts to define the parameters for the LiFePo4 10kwh smart battery. Annoyed to say the least , but is it (the MPPT), a goner ? Ex parrot ? ceased to be etc ?
Hi @Rik
Sorry to hear it. This is unfortunately one of those situations where it is better to be safe and sorry.
The MPPT was thinking that it was responsible for the battery voltage rising to unsafe levels, and the normal method for safely controlling battery voltage (adjusting PV voltage) was not responding as expected (because the power was coming from the generator instead), so it disabled itself to prevent an uncontrolled runaway.
I don’t think there is any recovery possible :(
Hi , thanks for getting back to me , I'm finding the transition from lead acid to lithium a fussy business... back to work then . Best regards Rik
If this is an unmanaged system, i.e., the battery is not in control of an installed GX device, then the battery BMS may be the culprit.
If you observed a voltage spike towards the end of the charging cycle, This is almost certainly a BMS protection event where the BMS cut the battery out of the charge circuit. The charger couldn't react quickly enough to suddenly seeing an open circuit and clamp down on the charge current to avoid causing a voltage spike.
This can happen with any charger. The more powerful the charger, the more severe the spike.
The best way to deal with this is to set your absorption voltage to 3.45V/cell or 51.75V for a 15S battery (48V nominal) or 55.2V for a 16S battery (51.2V nominal) with a fixed 2 hour absorption time. Disable any tail current settings. Float set to 3.40V/cell or 51V (15S) /54.4V (16S).
This will increase charge time and decrease current/power sooner and to lower levels as the battery nears full. It should reduce the frequency and severity of any spikes. Regular charges to full and daily It will also give the BMS additional time to top balance the cells.
