a 12v automotive battery is fully charged when it reads (1270 specific gravity) in all cells at 70 degrees F.
specific gravity is read with a cheap hydrometer. parts stores have them...cheap....... wear gloves and eye protection. correct electrolyte levels with distilled water.
if you use a volt meter, you are looking for at least 12.6 volts, or higher, as an estimate. any other method is also an estimate. it does not measure variance between cells.
if a battery goes completely flat it cannot be fully charged in less than 4 hours and 20 minutes. using a technicians charger that is.
a homeowners trickle charger can take days. any other method promises more because its designed to save time and it is an estimate that will get you by.
its an accepted fact in the original publishing regarding ohms law.
your dealer will have the appropriate test equipment and supplies. if not then they sell alot of batteries
Check with multimeter.
If in vehicle, try starting it.
Just a quick way is to measure the voltage. 12.6 is considered a good battery. You really need an actual digital battery tester though.
most battery charges now are automatic and stop charging just before the battery is fully charged, some even have different colour lights to indicate % charge.
Without the correct (expensive) gear, you can't.
Work it out, if the battery's flat & it's a 60Ah battery and your charger delivers 5 amps then it needs 12 hours to charge fully.
Green light will blink
SIMPLE ANSWERS ONLY please
