Battery questions

Duane Siegfri

I just load tested the batteries and found Mastervolt Gel Cell batteries.  4 out of the 12 in the house bank have failed (see the link below).  There was one pair that failed together, the other two are linked to good batteries.  There wasn't a date on the batteries, so I have no idea how old they are, but I assume they are not original.

I also have the Leece-Neville 175 amp alternator on the engine and there is no external regulator, so it's undercharging the batteries, but at least that's better than overcharging them.  Maybe down the road I will install the external regulator.  

I also have the Dolphin 30A and 100A "Power First" chargers.  The 7 page brochure I have notes Gel charging at 28.4V (boost) and 27.2V float and for wet batteries (i.e. "free") at 27.7V (boost) and 26.5V (float).  However I don't see how you would switch the chargers from gel to wet or vice versa.  The Xantrex Battery monitor shows the float voltage to be 27.19V.  I have the charger turned off now, so later I'll check the boost voltage.

Two questions for the group:

1.  Would you replace all twelve when four have failed?

2.  Is there more information on the Dolphin "Power First" 30A and 100A chargers?  I can't find where you would select the type of battery being charged.


Wanderer SM #477

If one downloads the Mastervolt manual for their 85A gel battery, it specifies 13.8V float (≈27.6V in series).

At first blush, the Dolphin charger, if it floats at 27.2V, might not be compatible with Mastervolt gel batteries.

SM2K No. 350 (2002)
At anchor, Le Grazie

Duane Siegfri


On the battery itself it listed:

Float: 13.5 to 13.8V
Absorb 14.25 to 14.4V

which corresponds closely to the 7 page (very synoptic) Dolphin manual I have from the previous owner which has a setting for Gel Batteries of 

Float 27.2V  
Absorb 28.4V

so it seems to correspond pretty well.  However, I'm not sure how to switch the Dolphin back to the wet cell settings.

Best regards,