So was mine. But would only charge to 13 and change but the ammeter was showing a 10 amp load with nothing but the engine running.
I put the battery on a charger till it went into trickle charge mode, took only an hour but the charging voltage was only going up to about 13 and change. The car would also only go to about 13 and change, but show 10 amps charge. 1st line right of center.
After I replaced the battery the car would go to about 14 and change but not show much on the ammeter
Both batteries had resting voltages in the 12s
Batteries have a built in resistance. As they age the resistance increases.