Battery Charging

For a 12V battery to be fully charged it must have a voltage of 14.2-14.4VDC (Volts DC). If batteries are not fully charged then the battery will degrade and over time a 200Ah battery will begin to perform like a 100Ah battery. Once the battery has reached this state of charge then it must be kept at a constant voltage of 13.2-13.4VDC. This is the float voltage. If the float voltage is too high, the battery will begin to "gas", boiling off electrolyte and shortening the life-span of the battery. These different stages of charging is called "multi-stage charging".

Not all battery chargers are capable of performing multi-stage charging, and they therefore reach a compromise between the two stages. Charging a battery at 13.8VDC. The result of this is a slow incomplete charge, excessive gassing and once again resulting in a shortened life-span of the battery.

Many of today's inverters incorporate a battery charging circuitry. This is easily done as an inverter changes DC current to AC current, and a battery charger does exactly the opposite. So it only takes a few additional circuitry for an inverter to multi-function as a battery charger. In these inverters, transfer switches are also incorporated. Therefore, when a generator is attached to the inverter AC loads will run directly off the generator and when the loads are not in use but the inverter is still running, this electricity will be used to charge the batteries.