I just got 4 new 12 v sla batteries. I started to charge them, and the green light was already on on the charger. Does this mean they are fully charged already? I'm just learning about electronics. I just don't wanna mess up the batteries. They are reading 51.1
over 6 years ago
The light turning green on the charger indicates that the battery pack is charged up to the full level, however with brand new battery packs it is recommended to leave the charger on the battery pack for around 12 hours for the very first charge.
The reason for this is to give them a deep initial charge before they are used. New batteries will will charge to a full level fairly quickly but then a short while afterwards their Voltage will drop a little, and the charger will bring their Voltage up again. This process will repeat itself until the batteries are deeply charged and ready to be used.
If the batteries were used without giving them an initial deep charge no harm done, just give them a deep charge now and they will be fine.