Battery Charging Information Figure 4-1 PWM Charging mode ·Bulk Charge In this stage, the battery voltage has not yet reached boost voltage and 100% of available solar power is used to charge the battery. ·Boost Charge When the battery has recharged to the Boost voltage setpoint, constant-voltage regulation is used to prevent heating and excessive battery gassing.The Boost stage remains 120 minutes and then goes to Float Charge