Battery State Of Charge (SOC)

One of the most common questions our customers ask us is “how do I know when my battery is fully charged”?
Who better to answer a charging question then NOCO Genius one of the worlds most respected battery charger companies.
According to the NOCO technical department, a batteries State of Charge measures the available capacity of the battery, which is expressed as a percentage. State of Charge is rated from 0-100%, with 100% representing a fully charged battery and 0% representing a fully discharged battery. A batteries State of Charge can be measured by reading either the terminal voltage or the specific gravity of the electrolyte. Terminal voltage can be measured with a volt meter, whereas, the specific gravity is measured by using a hydrometer. Battery hydrometers can only be used with flooded batteries, not sealed (Gel Cell or AGM) batteries.Below is a SOC reference chart for terminal voltage and specific gravity readings for a 12V lead acid battery:

As you can see from the SOC reference chart a battery that is 100% fully charged will have a voltage of 12.70 and a battery that is only 50% charged will have a voltage of 12.20.
All of the NOCO Genius multi-purpose chargers are designed to diagnose, recover, charge and maintain your batteries so you never have to worry about the SOC when your Genius charger is connected.