[serdeniz]

Hello,

There is a very strange problem in 24V DC system of a sailboat. There are three 24V battery bank (domestic use) which consists of two series 12 Volt batteries (There are 6 batteries). Three banks are connected in parallel.

Captain says that one of the batteries in each bank gone dead after 3 months. In each bank the battery which connected as – 24VDC was dead.

+ Batt1 - + Batt2 -

24VDC loads are supplied from (+) side of Batt1 and (-) side of Batt2. (I could not upload a figure, sorry)
In each bank Batt2 was gone dead.


He replaced dead batteries with new ones but he made a fatal mistake: He purchased smaller capacity (AH) and starter type batteries. He installed 182 Ah starter battery in series with 225Ah service battery to have 24 V seervice bank. Now I check the 182Ah starter battery and it is dead, inevitably. He admit his mistakes but, again batt2 (starter batteries) of each bank is gone.

There is a Mastervolt Mass 24/100 charger, one of previous models. Batteries are gel type batteries. I suspect if mastervolt is adjusted for wet type batt. I have checked electronic board but could not find any dipswitches where you can make adjustments.

There is also another battery which gives 12 VDC for electronics. There is a DC to DC converter to charge this battery from the 24VDC system. This battery is OK. Minus of 12 VDC is connected to minus of 24 VDC system by a circuit breaker. I don’t know if this breaker is necessary but captain said that one of his electrician told him that batteries in 24 V bank are decharging over this connection so there must be a isolator (diode). This sounds me nonsense.

I am sorry for my incapable English but hope you understand the situation.
Is there any comment on the problem?

Thank you in advance.