xantrex xc 2524 overcharging

I have a Xantrex model xc 2524 24 volt/25 amp battery charger that seems to be overcharging. It charges a pair of 8D house batteries that are set up for 24 volts. For years when we are plugged in at the dock with the charger on the house batteries stay at a constant 27.2 volts. About three days ago they are suddenly reading 29.5 volts (on the Link 2000 panel). There is very little draw on the house batteries when docked, just LED interior lighting. For now I am turning it off until the batteries cycle down to about 24.8 volts and turning it on until they hit about 27.5 volts.That's what they do when on the hook and are running the refrigerator and running lights . The batteries have never been cycled down past about 50%, and although six years old have not been discharged even to that level very often. These are lead acid batteries which have always been kept filled to the proper level with distilled water. I do see the temp sender on the battery terminal is cracked where the wire enters the plastic housing. Maybe that's the issue? The digital display in the charger stopped working last summer after we had some reverse polarity issues at the dock which turned out to be a loose ground in the dock pedestal. Also created an over voltage spike and multiple short term power failures. Maybe the unit is giving up the ghost after that abuse?

What was the temperature where the batteries live? If cold, the temperature sensor could still be working and instructing the charger to charge at a higher voltage. LA batteries have a negative temperature coefficient: the lower the temperature, the higher the required charging voltage; and vice versa.

Charlie has a good point. According to Trojan battery specs, at 50 degrees F one could be well into the 28.x volt range for float and well into the 29.x volt range for bulk charging. At colder temps the battery voltage could be higher.


Ken

Hmm, that is a good thought. I've been laying up in a marina in Palm coast Fla. for the last month. We have had some colder temps and no engine heat at all. Temps rising into the mid seventies by the weekend. I'll see what happens. Also will monitor engine room temps, 50 or lower would not surprise me recently. Thanks

Good points made above. Are you having to add water to the batteries more frequently? That's an indicator of overcharging. When and how are you taking that voltage reading?

No sign of over charging at the batteries themselves. No boiling, no drop in electrolyte level, tops and caps are clean and dry. The Link 2000 monitor is always on and before this anomaly so was the charger. The Link monitor has always read 27.2 to 27.4 volts when the charger is on continuously when plugged in at the dock. We've been living aboard full time since May 9th. I see the monitor many times a day due to it's location.This is the first time it has varied from it's usual readings.I monitor the battery voltage when on the hook and run the genset as needed to re-charge. Never go below 50% discharge and rarely that low.I also check electrolyte levels about once a month or so. I read a great quote- "most batteries don't die- they are murdered".