Battery voltage

[bassfisher]

What is the voltage of a fully charge battery, and does it hurt them to charge them (top them off) even though they are charged? 12.5 to 12.9V

When I charge my batteriers they are charged at 13.7V (I think). Once they are fully charge and I disconnect them they run down to about 12.9V within a few hours (I have no watch that closely), and stay there for a long time. After a few mouths or more, they can run down to 12.7 to as low as 12.2. (Never useing them)

I'm asking this because here of late, when charging my batteriers, they do not charge right. (They never say full.) I have bought a new charger (walley), and still does this sometimes. I have one new TM battery 2 weeks old, the other one, I have no ideal, but it holds a charge for a long time without use, and with use it last me all day for medium use. ( MG TM 67lb thrust 24V , useing it on 1 to 3 speed out of 5, depending on wind, and only use it to move the boat or keep it straight. So no constant use)

[skeeter1804]

The voltage of a fully charged battery will range from 12.4-12.7 volts. A 12 volt battery should never hold a charge at 13 plus volts. The battery charger may be charging at 13.7 volts but when the charger is turned off the battery should stabalize around mid 12's.

[bassfisher]

Also does it matter which type of battery charger we use? (Car battery charger virus marine deep cycle cell charger) I'm useing a car charger.

[CamG]

Originally Posted by bassfisher

Also does it matter which type of battery charger we use? (Car battery charger virus marine deep cycle cell charger) I'm useing a car charger.

I have been told by many to never charge a marine battery with a car charger...don't exactly know the reasoning, but all that I can say is that my batteries last at least 4 years, sometimes more. I charge with a marine trickle (2 amps I believe).

[Abbeysdad]

I use a fairly new Shumacher Ship 'n Shore 2/10/15 amp Multi-purpose (marine) charger I got at walmart. It can handle larger deep cycle (15amp) as well as smaller deep cycle and car (10amp) and lawn tractor (2amp) batteries.
In addition to amps in charging, It also has settings for standard, AGM and gell cell type batteires.
I'm usually set on the percentage readout, but believe the batteries change to 12.9~ amps or so. I also know that the battery continues to charge for some period after the calculated read-out reaches 100 percent. This concerned me until a Shumacher techie assured me that the pc that controls the charge really doesn't use the percentage (a calculated avg) in it's charging routine. Anyway, it works and works well.
I have no experience charging deep cycle marine batteries with automotive trickle chargers.

[Embrey]

fully up, mine usually show 12.9-13.1 always

[Rebbasser]

Although they cost more than a car or trickle charger if you can I cannot recommend an on board charger highly enough. I plug it in when I get back from the lake and unplug it when I head out. It both charges and maintains the battery-it is literally set it and forget it. It will not overcharge or cook your batteries but keeps them ready to go at all times.