Low voltage on RV batteries

[wchoe]

I have a 24ft Gulfstream Mini Vista Cruiser Class B+, with three 12v deep-cycle lead-acid batteries totaling 310Ah. One older Interstate, and 2 EverStart batteries which are a year old. Lately, the voltage drops below 11v, even though only 25% of capacity is used in 1-day. The remaining voltages of the individual batteries do vary due to the way they're hooked up. Have tested them with battery analyzer and load-tester which says they're good. I use them mainly for lights, water-pump, e-bike, laptop, phone.

The RV converter charges at a constant 13.4v when hooked to shore-power. Also have a DC-to-DC charger which does multi-stage charging when driving. Wonder whether the different ages and capacity of the batteries, is causing this problem.

Please let me know if anyone knows why this may be happening.

Thanks