12v Battery Charging Query

[Doug99]

I am preparing for winter and charging my 12v car battery 'out of the car' in 'normal' mode of the charger. I have topped up the cells and monitoring the 'charging cycle' by a seperate multimeter.

The charging votage has increased from 14.95v to 15.64v in an hour. When is the battery fully charged? Is it when the voltage levels out to a constant figure? I remember reading somewhere that the figure can begin to fall again but not sure.

VMT

 

[Burnerman]

The battery charge capacity is best looked at by the amount of amps it is consuming, rather than volts.
To check the correct charging voltage, connect a 'dummy load' across the battery (a 12v lamp bulb is fine). This will indicate the actual charging voltage accurately when you measure it with a multimeter.
John

 

[Mursal]

Use a battery hydrometer over a period of time to see if the specific gravity of the acid is changing (1.25 to 1.28 =full charged).

 

[Doug99]

Thanks both.

 

[Peter.N.]

If the battery is good, fully charging it every six weeks should suffice.

Peter