So the solution to this problem is fairly straightforward. Just add another switch. So in addition to the high side pass element that routes current in from the external source, add one more switch in between the system node and the battery itself. This allows us to decouple the battery from the system when needed. For example, if the battery is deeply discharged, and it is plugged in an external adapter, it is possible to isolate the very-low-voltage cell from the system, power up from the external supply, and then take any action needed such as pre-charging the battery until it is high enough to “share” the system node. This approach also allows the charger to independently monitor the charge current into the cell itself vs. the total current drawn from the adapter to check for any fault conditions.