u/hevis

I have 3x220Ah AGM batteries (same brand and model, bought at the same time) connected in parallel in my off-grid setup. Charging is handled by a Victron SmartSolar, discharge only via Victron MultiPlus. The setup is in Finland, unused during the winters (temps get down to -25c).

The setup has worked fine for the last three years, however, this spring I noticed corrosion on the positive terminal of the primary battery to which the other batteries are connected to.

Is the sudden corrosion a symptom of something that should be dealt with?