Recently I happen to replace a new iPhone 4 replacement battery, with a little bit of peel down of the battery, I saw there is a bare lithium battery unit with a PCB battery protection board.
My idea is to lead two wires from the input to an external pack of 3 paralleled Panasonic NCR18650A (3100mAh 18650) batteries, totalling battery capacity to around 3.7v 10Ah.
My question is will this work? Charging and Discharging, reasonable accuracy on the percentage of battery capacity measuring? Thanks.