Batteries and Cockpit Power

LUnaCY

Active Member
Aug 28, 2018
206
Afton, MN
Boat Info
310 Sundancer 2002
Engines
Mercruiser 5.0 MPI Bravo III
I installed 2 of 3 batteries today. The third fluid level was way down over the winter trickle charge...I added 3/4 gallon of distilled water to it and put it back on trickle. I wont be surprised if I have to buy a new one.

But...after installing 2 batteries and turning on my battery master i could get only the blowers and ignitions to power...no lights, no hydraulic bilge lifts, no trim tabs. The two i installed were the ones in series. Not sure which powers what..generator, l/r engine. There is a third with separate cables that Ill get to tomorrow...hopefully that gets the rest of the boat powered. A bit surprised that the batteries arent tied for cockpit power.

Was hoping to have the hydraulic engine compartment working since its so heavy.

Vent complete.
 
Reading others posts. Maybe i made a bad connection on one battery. Seems the grounds are common, but the positive is separate.
 
There should be no batteries in series on that boat (unless someone changed them to 6 volt batteries). If they did get connected in series then 24 volts was applied to a 12 volt system; expect damage. A float charge (what many call trickle) should not boil a battery dry; there is an issue with the battery and some of the plates have shorted or there is an issue with the charger. Regardless if the battery took that much water then the plates were exposed and it is essentially toast. All of the grounds on the batteries connect to a common ship's ground buss as does the bonding system and AC power ground. Probably best to look at the owners manual for that boat and verify the battery wiring configuration.
 
Thanks for the info. I mix up series and parallel. But the grounds were common. The positives were separate.

It truly was 3/4 gal added. A little black corrosion I assume in a few cells after I inspected the added fluid.

Its only been on trickle overnight, but Ill take it in to have checked and purchase a new one. Doubt one overnight of trickle did anything or if they can tell.
 
The two batteries in parallel are the house bank and starboard engine. The 3rd single battery is the port engine and all helm electronics, including hatch lift.
 
The two batteries in parallel are the house bank and starboard engine. The 3rd single battery is the port engine and all helm electronics, including hatch lift.
Thanks! Thats what I was hoping. The first two are further back and the ones I installed. Ill get a new one today for the third.
 

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