I am designing a device that will have two 7.2-V Li-ion battery packs in series, arranged to produce bipolar supplies. The series connection between the batteries is my PCB's ground. The batteries cannot be removed for charging. One battery pack will see a greater load than the other one, so they cannot be charged in series (with a 4-cell charger); I will use one charger IC for each battery pack. Both batteries need to be charged at the same time, however.
So far the only method I've thought of to charge these batteries is to break the batteries' connection to each other and their connections to the loads during charging. I would do that by running all of these wires to a multi-pin charger receptacle. To actually operate the hardware, the user would insert a loop-back plug that would make all of the necessary connections between the batteries and the loads. Oh yes, during run-time I also need to break the Vin and VSS connections between the charger ICs, and use a local VSS for each one.
Cumbersome, wouldn't you agree? Any better ideas? Thanks...
