Car has been starting with difficulty for a week or two. Yesterday it refused to start at all. I put it on charge this morning and the meter showed 14v. Looked at it half an hour later and the meter showed 13.3 v with green light on saying charging complete. The car started. Does anyone have any suggestions as to what happened?

It charged, then it stopped charging; as intended by the charger's designer I expect.

 

Resting voltage (nothing connected, and not recently in use or on charge) of a fully charged lead-acid battery is about 12.6/12.7V.

 

Charging voltage has to be higher, and for a while afterwards the battery will still show this higher voltage. After an hour or two it'll show the 12.6ish volts if fully charged and the car isn't taking excessive current in its  'fully shut down' state. See below.

 

 

Many thanks, I'll connect the battery charger up later to see what it shows.

Wino is quite right,most automatic chargers cut out before the battery is fully charged. Sometimes you can't beat a non electronic charger.That is one which has a transformer to lower the mains voltage to about 16 to 20v ,which is then rectified to change AC voltage (and Current) to DC.  The battery is directly connected to the rectifier output.Even better if it has an ammeter to show the charging current at any time. 

Also it has been said many times before really cold weather sorts the good and the bad batteries out.  It is no good saying it reads 12-14volts when measured with a multimeter which takes a very very small amount of current.Try leaving the meter connected when turning the starter over (300 to 600 ammps load).You will be in for a shock it will read about 9v if the battery is OK,and next to nothing with a faulty battery.

Edited 8 January, 20215 yr by AndyPandy

I have just charged my spare battery which i do at regular intervals, my electronic charger also cut out too early in my mind given the low temperatures so after leaving it overnight I charged it again, it was reading 13.3 volts, I left it 4 hours & it was at 12.7v, however when I used my decent pulsed load tester it showed 300ah vs the 640ah rating and 20% remaining life, yesterday on the 2nd test it showed 5% remaining.

 

I dont think that its good enough to use on a vehicle now but might help for a very short jump start.

I conected my charger up and it read 12.06 % which the list above shows as 50% charge so I dumped it and bought a new battery.