I have a Multiplus 24/800/16 that used to run on 2 Lead Acid batteries (2x12V in series) but now has been fitted with a LiFePO4 battery (BLueNova BN26V-108-2.8k MPS).
The Multiplus worked fine with the Lead Acid batteries. But with the LiFePO4 one it behaves strangely. It starts fine, bulk charging at full current, but after an hour or so the inverter starts kicking in about every 20 to 30 seconds and then switching back to mains again. Occasionally the red LED comes on briefly and VictronConnect reports a "Battery Ripple". The unit keeps switching back and forth between mains and inverter every 20-30 seconds or so until I switch the mains off, let the battery drain for a few hours and then switch mains back on, at which point bulk charging resumes and I'm good for another hour or two (depending on SOC) until the battery voltage reaches a certain threshold and the whole problem start again.
I'm not sure if this has anything to do with settings. With the Lead Acid batteries I used the Multiplus out-of-the-box, but the LiFePO4 battery requires a few adjustments. So I did the following:
As per the Multiplus manual I set dip switch DS2 to ON, then toggled dip switch DS6. The lights on the Multiplus blinked to indicate that the setting had been stored.
In Victron Connect I made the following changes:
General - Enable battery monitor set to ON. VC now shows correct battery capacity of 200Ah.
Charger - Charge current set to 16A; Lithium batteries set to ON; Absorption voltage set to 28.40V as per manufacturer's specs; Float voltage left at 27.60V as per manufacturer's specs.
Inverter - DC input low-shutdown set to 23.50V. (The manufacturer specifies 23.2V as the minimum voltage at full discharge, but I don't want to discharge the battery that far so I've put it at 23.5V); DC input low pre-alarm set to 24.50V; DC input low restart set to 25.50V.
Nothing else has been changed.
The most obvious assumption would be that the Multiplus is simply rejecting the mains current quality, but then why would this not have happened with the Lead Acid batteries?
I experimentally reduced the charging current to 6A so see if that would make any difference, but it doesn't.
What can I do to troubleshoot this problem?
