All of these things are built into consumer devices already. 0% maps to about 5%, 100% maps to 90-100% depending on where in the charge cycle the device is (it

All of these things are built into consumer devices already. 0% maps to about 5%, 100% maps to 90-100% depending on where in the charge cycle the device is (it will stop charging for a while to discharge some of the battery before starting charging again).