12V Lead Acid Battery 6 cells have (for new battery) :
- Nominal Voltage 12V.
- 24h after charging OCV should be 12,72-12,73V (each cell is full at 2,12V, and discharged at 1,99V).
- Float Charge Voltage 13,5V-13,7V-13,8V (depends from temperature, for higher temp voltage is lower in desert at 50C should be around 13,2V). Battery can stay long time on charger at float charging voltage.
- In car/truck charging system, when engine is on and alternator charging battery, voltage on battery terminals should be 13,8V, and on alternator terminals 14,4V.
- In cars/trucks is used starter lead acid also called "float battery". There is deep cycle type of lead acid batteries with different specifications.
In cars/trucks vehicle battery have additional rule to make voltage regulation in vehicle electrical system, without battery voltage will have big variations in system with high voltage peaks.