How many volts should a 12v battery read?

[Michigan boarder]

I had my battery out over the weekend and it reads 11.75 volts. That means it is bad, probably has a dead cell, correct? Shouldn't it read like 12.25 or something? It stil fires the engine, good cranking power, and I have yet to have a problem. But from my experience with golf cart batteries, once a 6v battery drops below 6 it starts pulling down the others and you don't get much of a charge out of it. I had it on a charger, and when I took it off I had a meter on it, watching it drop to 12.09, 12.08, 12.07, etc. It stopped at 11.75.

Time to replace it? I was actually thinking of just using it for the stereo, and adding another battery for starting and "all other", and putting a blue seas switch in.

[shawndoggy]

[electricjohn]

I am surprised it will still crank the engine @ 11.75 volts. I always test a battery by putting a small (<2 amp) load on it and reading the voltage.

[Michigan boarder]

Wow, that is a perfect illustration. Thank you! Safe to say my battery needs to be replaced.

I am surprised it will still crank the engine @ 11.75 volts. I always test a battery by putting a small (<2 amp) load on it and reading the voltage.

Can you describe that more in detail? Not needed for this battery, I know it's time to replace. But I'd like to know for testing the future equipment.

[Earmark Marine]

You might try having it load tested or trying another battery charger or trying another measuring device. Once the charger is removed the charger is always going to leave an elevated and falsely high voltage for a short duration before that charge dissipates and finally settles over a little time. If you can get the battery to accept a full charge and the battery can hold a 12.5 volt or above for 48 hours in isolation then you are probably okay for the time being. But once the battery is degraded then get it out of the system as it is adding to the load on the alternator which isn't healthy and it will degrade any other battery in the system.

David