BQ24210: Multiple cells and chargers in parallel - charge mode and load mode

Part Number: BQ24210

Tool/software:

My device has an input for a a 5 to 12V plug pack, four separate 18650 Li Ion cells and a 3.6V regulator supplying the device (MCU, Cat1 Modem etc)

I'm thinking of providing each cell with its own BQ24210 charger for individual charging and management, supplying the VBUS pin of each charger from the plug pack. The four VBUS pins would be connected in parallel with the plug pack positive and the input to the 3.6 regulator.

Something like this

Power Source (VIN) 5-15V Plug Pag or similar
|
+- VBAT of BQ24210 (Charger 1) ----> Battery 1 (18650)
|
+- VBAT of BQ24210 (Charger 2) ----> Battery 2 (18650)
|
+- VBAT of BQ24210 (Charger 3) ----> Battery 3 (18650)
|
+- VBAT of BQ24210 (Charger 4) ----> Battery 4 (18650)
|
+----> 3.6V Regulator ----> Load

When the plug pack is connected, it will also supply the regulator, but when the plug pack is removed will the 18650 cells supply the regulator via each charger's VBUS pin switching from "charge mode" to "load mode".

Am I reading the datasheet correctly? Will this work, and will it protect the four cells? Will it draw from the cells evenly, and cope if a cell or cells are, for example, lower resistance than the others and supply more current than the other cells?

Comments and suggestions please.

  • Hello,

    I do not think this application will work. While all batteries charging should be fine, when the load mode is enabled for all the devices, the highest device will end up charging all the other parallel devices. This is because the load mode and charge enable control are controlled by the same pin.

    Regards,

    Mike Emanuel