These three components, when put together, take any type of AC power, be it clean, dirty, or anywhere in between, and push it into your electronics. Here is how it works.
The battery charger takes AC power from the wall, and turns it into clean DC power, eliminating spikes, sags, lags, and transients. The power that the batteries can either take if they are not full or pass along to the load is regulated DC clean power. If the batteries are full, the charger simply slows way down, in a regulated and controlled manner. Should the power from the wall go too high, the battery charger speeds up. Should the power go too low, the battery charger slows down to compensate. At all times, the battery charger keeps the reservoir of power in the batteries at or near full, and elimnates any noise from the AC power grid in the process.
When the electronics need power, they get it from the batteries, via the inverter. The inverter takes power from the DC power circuit, either from the battery charger directly, or from the batteies as needed. This eliminages low voltage, amperage, and intermittent power supply issues.
Between the two processes, AC - DC conversion, storage, and subsequent DC- AC conversion of the power; virtually all power problems associated with electronics can be eliminated. The battery backup system uses the switching of power between AC-DC to clean the supply, and DC-AC with a reservoir to fill in any gaps. Click here to understand what power Lags, Sags, Spikes, and Transients are.