PWM Charge Controllers

A charge controller is an electronic voltage regulator, used in off-grid systems and grid-tie systems with battery backup, that controls the flow of power from the charging source to the battery. The charge controller automatically tapers, stops, or diverts the charge when batteries become fully charged. Some charge controllers have metering and datalogging capability to show system operation parameters and battery charge status. Some have low battery load disconnect to prevent over-discharge and some have built-in light controls to turn on lights at night.

Charge controller capacities range from 4 amps to 80 amps and multiple charge controllers can be used in parallel for larger systems. The simplest charge controllers turn off the charge when the battery reaches a voltage near full charge, and turn it on when the voltage drops about one volt. Pulse width modulated (PWM) charge controllers turn on and off very rapidly, holding the batteries at full charge, making better use of available power.