Battery water level

[edwmama]

Hello fellow sailors


Can anyone tell me or educate me on this issue that baffles the heck outa me?

Besides my separate starter batteries I have two sets of house battery. One set consists of two 4D connected in parallel. Another set contains four 6V batteries in which 2 pairs are in a series which In turn are in a parallel connection. My question is. Why is it then when I go to top off the water the 4D never require water but the 6 V always do even though the 4D are my primary bats? I am using the 4D and they are always full and the 6V are back ups yet they are always low every two months? Mysterious


Edwin
Lahlia
Cal Cruising 46
Marina del Rey CA

 

[Rich Stidger]

First, I presume that all of these batteries are the same technology. If you are mixing AGM batteries with flooded cell batteries you will always have an imbalance in the charging rates. This is a big NO-NO.

If you are charging the 4D's and the bank of golf carts in parallel, the 6V golf carts have a lower internal resistance. That is to say they will accept charge more readily than the 4D's.

Hence the 6V bank gets most of the charge. You may not be discharging the 6V batteries but if your charger has two outputs that connect to the 4D and to the 6V banks, every time you charge these two banks, significant charge goes into the 6V batteries that are already fully charged. This excess charge will boil off the water in the 6V batteries.

This is one reason why you should always have the same brand, size,and date code for all of your house batteries.

 

[Benny17441]

Also age and condition of the batteries could be a reason.

 

[Bill Roosa]

The 4D are used and not sitting at full charge like the 6 volts are. Batteries that are fully charged will boil off water when you drain the other bank and then charge it and the 6 volts at 14.4 volts.
I'd recommend that you combine the two house banks into one to preclude this from happening

 

[monkeybars]

impossible to tell without knowing what your charging them with,and how the charger is wired to the banks,you could have it wired wrong, what are your 24hr resting voltage readings on each bank,before and after charging,what are your voltage readings on each battery during charging,there are many possibilities.