Fully charged it should read 12.6 volts with a digital volt meter. 12.4 = 75% charge, 12.2 = 50%, 12.0 = 25%.
Fully charged battery should have 12.6 volts. 75% charged 12.4 volts, 50% charged 12.2 volts, & 25% charged 12.0 volts.
With a fully charged battery (12.68 volts) and engine running at idle with no accessories on, 14.5 volts. You will not get a accurate reading if the battery is not fully charged.
12.6 volts as read with a digital DC volt meter.
12.6 volts at full charge. During charging at least 13.8 volts are applied to the battery.
A fully charged battery cell typically has a voltage that varies depending on its chemistry. For example, a fully charged lithium-ion cell typically reaches about 4.2 volts, while a nickel-metal hydride (NiMH) cell reaches approximately 1.4 volts. Lead-acid batteries are fully charged at around 2.1 volts per cell, resulting in about 12.6 volts for a typical six-cell battery. Always refer to specific manufacturer specifications for precise values.
A fully charged 12 volt battery will output 12.6 volts are read with a digital volt meter.
With the engine not running you should read 12.6 volts on a fully charged battery. With the engine running you should read from 13.5 to 15.5 volts at the battery posts.
A fully charged 12 volt automobile battery will read 12.6 volts with the engine not running and 13.5 to 15.5 volts with the engine running. It will read 12.4 volts with a 75% charge, 12.2 volts with a 50% charge and 12.0 volts indicates a 25% charge.
Each cell of a modern lead-acid car battery should have an average voltage of about 2 volts but - depending on the cell's condition and its state of charge - the exact voltage at any time may be somewhere in a range from about 1.8 volts (when it is almost fully discharged) and up to 2.25 volts when it is fully charged.
2.2v when charged.
A battery float charger is intended only to keep a fully charged battery from losing its charge. It will NOT work to charge a battery that is discharged or damaged. Check the voltage of the battery to be charged. Do not use charger if the battery voltage is less than 9.6 volts.
It varies by manufacturer and battery.