BQ24133 adds backup lithium battery pack

SuperShen

BQ24133 adds backup lithium battery pack [Copy link]

Now I am designing a circuit for charging three lithium batteries using BQ24133. The design requires adding a backup lithium battery power supply. If I directly add the backup battery to the output of the BQ24133 power supply with a diode, if the system power supply is higher than the original lithium battery voltage, will it cause BQ24133 to misjudge and turn on the MOS tube of the external power supply to charge the internal lithium battery? Or how should I design it if I add another backup power supply?

qwqwqw2088

The system power supply has a high lithium battery voltage, which may cause misjudgment. The backup lithium battery power supply also needs to be charged. It is best to design another set of charging backup

SuperShen

qwqwqw2088 posted on 2018-4-17 15:31 The system power supply has a high lithium battery voltage, which may cause misjudgment. The backup lithium battery power supply also needs to be charged. It is best to design a separate charging backup

If I want to connect to the backup power supply, do I have to connect a diode in series at the 24133 output position?

qwqwqw2088

SuperShen posted on 2018-4-17 19:01 If I want to connect to the backup power supply, does that mean I must also connect a diode in series at the 24133 output position?

Connecting a diode in series at the 24133 output position can be switched. You should choose a Schottky with a small forward voltage drop. It is best to choose a power MOSFET switch to replace the diode. The problem is, if I understand correctly, it is the switch between the main battery and the backup battery. When the main battery is powered, the backup is charging. Then, when switching power supply, you also need to switch charging. In this case, it is recommended that both the main and backup batteries have a set of charging circuits, and then switch the main and backup batteries for power supply.