Anyone know the exact Voltage of a fully charged boat battery?

[cantermore]

I know this almost sounds silly; but might anyone know the exact voltage that should be in a fully charged 12 volt boat battery? one would think by the name its 12 v of course but for some reason I thought it was more..

 

Thanks

[irishfield]

If it's been charged and sitting for a few days...usually about 13.2 to 13.7 Volts If it's less than 12..she's toast

[cantermore]

Thanks, I have an older manual charger on it & pulled it off at 12 & its holding around there, I have a meter on it but will let it run a bit more to get it up there.

[irishfield]

If it's holding at 12 it should charge some more. You have 6 cells...each produce about 2.2 volts when charged..so if you have a bad cell you'll only get about 11.4 volts or so...

[huey graphite]

Make sure when you test the battery voltage you have a load applied such as running the trolling motor or a bilge pump (something with sufficient amp draw.... lights aren't enough). This will give you a true indication of the status of your battery. With no load your only getting a "surface" voltage and even bad batteries can sometimes read 12V.

 

Typically a fully charged battery should be around 13.0V under load. A discharged battery will measure 12.0V or under. Batteries significantly under 12.0V will sulfate and have very little run time.

[irishfield]

..and what Huey said! Had a customers battery that wouldn't start his airplane last week. It had 12.8 volts...and absolutely not a drop of acid left in it from him overcharging it all summer at his cottage.

[cantermore]

going out to put the charger on it now but will find something to load it down first, I know I have a 12 V compressor that should do it. If not the downriggers are here too

 

Thanks again