Compared to Li-ion batteries, Lead-acid batteries have a wider recharge threshold. The charger begins in CC mode and then switches to CV mode. From Figure 25 charge regulation voltage, and float voltage can be calculated according to Equation 1 where R1 = R15 when Q3 is off, and R1 = R15||R16 when Q3 is on. The circuit uses the STAT2 pin, which is pulled high while the battery is charging, to turn on Q3 and increase the charger’s CV regulation point, to the battery’s bulk voltage until the charger senses that the current has tapered off. Once the charging current falls below the termination current threshold, STAT2 goes to low impedance. This causes Q3 to turn off, thus lowering the recharge threshold voltage, VRECHG, to the battery’s float voltage. When VBAT drops to VRECHG, the charger returns to CC charging and sends a pulse of current to recharge the battery to the bulk voltage and the cycle repeats.