Are these deep cycle batteries? Why can't I check the electrolyte levels?

[Shaneesprit]

Originally Posted by PippaB

The HX500 is rated at 119Ah. I would call it the opposite of deep cycle, it is designed to be fully discharged in 15 minutes, allowing lots of power for a short time to allows orderly shutdown or transfer to generator in data centers.

And you don’t want run them below critical cell voltage - can’t remember the cell value off the top of my head. Fully discharging these sells really damages their future performance, you can do it once when new. To prove your system AH, quite common to get a few failures and heat when discharged fully and fast. Last one I tested blew the cap out of the battery, even if a battery failed would never retest, as the other cells would be depleted.
Discharge time normally around 10 mins with an End of life 6.5 min ( called 10 years but they never last that long) Also storage Temperature less than 25C better at 22C. Warmer cells equals considerably less battery life.

[dmkkeng]

Originally Posted by Whiteoil

It's the original Bavaria charger from 2007, I've been living on the boat all summer this year so it's constantly recharging the batteries. The fridge and lights run off the battery and the battery charger recharges.

It's a 12v 25amp SBC quick charge. Should I pull it out tomorrow and work on it? Anything I could fix on it? This nose will keep me up at night!Attachment 259695Attachment 259696Attachment 259697Attachment 259698

It appears that you don't have the optimum type of batteries on your boat per other comments. I haven't heard of anyone using UPS application batteries on a boat. Also your charger is under sized for your battery bank. A general sizing rule is 10% of the battery bank size/ capacity. Cooling fans can generate a lot of noise, perhaps the charger cooling fan is starting to fail? As others have mentioned the best test to check the batteries is to do a load test, there are battery specific parameters for doing this test, also you should to do each battery seperately.