BQ25703A: Lead Acid Battery Charging

Hey Franz,

The BQ25703A charging profile is completely adjustable/programmable by the host controller. The only profile the device handles automatically is the transition between CC and CV modes. Other than that, the charging regulation threshold, maximum charging current, and charging current profile are all adjustable by the host.

For Lead Acid batteries, there are two common ways to charge. The first is a low-current CC-CV charge profile that charges to what is normally called the float voltage. The other common method is to have a low current CC charge up to an "Absorption Voltage" that is higher than the float voltage, and once there, transition to to a float voltage that keeps the battery charged to that level indefinitely. 

Again, you would have to implement this in your host, but it is mostly a sequence/flow diagram of I2C commands to the charger.

Regards,

Joel H

Hey Franz,

That is correct. If you look at the charge profile for Lead-Acid vs. Li-ion, the main differences are (optionally) the Absorption voltage, and pre-charge current (which must be controlled by the host on this charger anyway), and the termination current (because Pb-Acid does not terminate charge and is kept at the float voltage).

Regards,

Joel H