The BMV is currently set to 440Ah because two batteries were disconnected after swelling was observed.
Originally the bank was 6 × 110Ah AGM (660Ah total), all in parallel.
Even with the reduced 440Ah bank, the remaining AGM batteries are showing signs of swelling.
Charging setup remains:
3 × Victron MPPTs
Victron MultiPlus 3000W
Absorption: 14.40V
Float: 13.80V
Equalization disabled
Temperature compensation: -16.2 mV/°C
Batteries are installed in a warm / tropical environment and usually reach 100% SOC daily.
Given this, I’m trying to confirm whether:
These voltages are simply too high for sealed AGM in hot climates over long periods
Absorption time (with multiple MPPTs) could be excessive
A lower float and/or absorption voltage would significantly improve AGM lifespan
Appreciate any insights or recommended “safe” AGM settings.
Its important to know if this is actually correct for your batteries. And then also have a temp sensor on the ve bus as well (it comes with the unit) and make sure it is working.
Second thing is to check the C rating if the batteries and that has been exceeded as well as make sure excess bulk charging prevention is enabled.
I am not a fan of daisy chain set ups. But it seems even the middle one is having issues.
Could just be the heat. By warm- what temperatures do you mean?
You look like you have Victron AGM, I had Victron AGM before swapping to Victron Lithium. I used a temperature compensation of -24.5mV/C for 12V batteries taken from one of the Victron AGM datasheets or manuals and had a temperature sensor on the batteries, do not rely on the one in the MPPT and make sure DVCC and STS is enabled based on the correct sensor. Also I suggest that you would be better with a lower float, say 13.5V. A lower absorption may be advantageous with large numbers of batteries in parallel.
The one issue seen in boats is alternator charging from stock alternators with 14.4-14.6V regulators, there is no float so they get overcharged. If this applies you need an external regulator.
Hot AGMs see an issue where the hotter they get the lower the resistance, so more current flows generating more heat. Sometimes tail current is never reached.
