Can a 12V Lead Acid Charger Charge a 4S LiFePO4 Battery? Why 14.6V Does Not Mean Compatibility A common customer question is: “I have a 12V lead acid battery charger with a 14.6V or 14.7V output. Can I use it to charge a 4S LiFePO4 battery?” The answer is: A standard 12V lead acid charger should not be used directly with a 4S LiFePO4 battery unless the charger manufacturer specifically states that it supports LiFePO4 charging. Although a typical 4S LiFePO4 battery has a full charge voltage of about 14.6V, and some 12V lead acid chargers may also have a charging voltage of 14.6V or 14.7V, similar voltage does not mean charging compatibility. The charger must also match the battery chemistry, charging algorithm, constant voltage stage, and charge termination method.