Hi, my agm batteries (10x 12v 230ah) have a 14,6V - 14,8V bulk and 13.6V - 13.8V absorbtion voltage. I already reduced the voltage to 14,5v for bulk and 13,5v for absobtion. But they all make a very low bubbleing noise. Is this dangerous for the batterie and do I have to reduce further? Thanks
If the Battery bubbles, that usually means, you produce Hydrogen and Oxygen (some call it HHO). That's explosive. That usually means, you loose water from the battery - need to check, if they need to be refilled.
If the water gets too low, the plates in the battery will be exposed to air -> not good. Also the acidity might get out of balance.
With AGM however, they sould be sealed, right? So none of the produced gases can escape? I assume they have some kind of a pressure relief? On the other side, I have seen sealed batteries, which will start to bloat. Careful.
In general, why the Battery bubbles, before totally charged, that is a question I can not answer, but am curious too.
I have one well used 230Ah Lead-Acid starter Battery, which has a similar behavior. Use an automatic charger (a bit weak, only 10Amp max), and the charger wil never show full Battery, but the battery starts to bubble. On other Batteries (admitted, the have on 70-80Ah), the charger will show fully charged, and no bubbling issues.
I assume the bubbling, before fully charged, could mean one of the following, even though this are just some thoughts and I am not sure, hope one here will be able to shed some more light on the topic:
I managed to cook a gel battery (internal short between plates) which was bubbling while releasing gas and acid through the relief valve. Obviously it was also bloated but luckily no explosion which can also happen with dramatic effect. AGM will be no different. Both can and do sometimes dry out eventually.
I would be very suspect of a VRLA battery with audible bubbling.
Bubbling could also occur from a high charge rate during the "bulk" phase (which occurs before reaching absorption voltage). Try lowering the charge rate to 10% AH capacity (100 AH bank would have a 10 amp charge rate). Official recommendation says to keep charge rate at a max of 20% AH, but "ideally" be 10%.
