Charging batteries on shore power

[lawrence_craig]

Hello all.

I have a pretty new set of Bosch 12v batteries onboard. Bought in August last year, used for about 60 cycles max, not dropping below 60% charge.

I have since been living onboard connected to shore power with a Victron Centaur charger.

Normally, the voltage from the charger sits around 13.5-13.6 volts. I assume this voltage is coming from the charger to keep the batteries topped up whilst we use the 12v services.

However, today, whilst doing some work on the 230v system, the batteries dropped to 12.4V. This suggests to me that there is either a problem with the batteries (losing charge quickly) or with the charger (not charging the batteries correctly).

Has anyone had a similar experience? Any advice?

Thanks,
Lawrence