First time of posting so here goes!
My Mastervolt MASS 12/60 has suddenly started charging at slighty higher voltages and I'm concerned about reason for this and the damage it may do to my batteries.
The system is a Mastervolt MASS 12/60 supplied by either a landline or on board generator, a Mastervolt MICC monitor/controller and a 550ah domestic battery bank (3 - 4 year old AGMs). I also have a Sterling 150 amp 3 step charger as a backup.(in reality this is 2 chargers separately switched in one case). I should stress that this unit is not part of my problem
Up to recently the charge voltages were exactly as stated by Mastervolt eg in bulk rising to 14.4 v, in absorption constant at 14.25 v, in float constant at 13.8 v (with dip switch set to Gel compensation). Now they rise to 14.62 v in bulk, remain at 14.62 v in absorption and fall to 14.3 v in float. Setting the Gel compensation to off reduces the float voltage 13.6 v.
The MICC has been checked against 4 digital meters, including one that had recently been calibrated, and is accurate to within .02 of a volt at around 14 v. It is wired to sense at the batteries. Voltages have been double checked back as far as the battery bank using several digital meters. All cables, connections have been checked and double checked. All cables and wires are significantly over spec ed.
I temporarily replaced the batteries with 2 almost new 110ah ones with the same results.
If I switch off the Mastervolt and switch on the Sterling charger (half of it) I can continue to monitor charge voltage via the MICC. Whilst I can't quote offhand the bulk and absorption voltages I do know that it settles down to a float voltage of 13.25 v.
I have spoken to someone at Aquafax who are now the UK agent for Mastervolt and he didn't seem to think I had a problem!! He suggested it could be the batteries (since proved not to be so). He also suggested it might be the heat (we were talking during our brief summer a couple of weeks ago). Not so as the problem pre-dates that time. His final and most forceful 'explanation' was that by disconnecting the boat from the mains when I left it for any any time I was using the charger incorrectly and that it should be left connected 24/7. He didn't want to hear my point that my concern was that the charging characteristics had changed.
Am I worrying over nothing or is there something wrong somewhere? Have I overlooked something obvious?
Any help or suggestions would be much appreciated