Originally Posted by
gauvins
The usual recommendation is to charge a battery rather than a device such as a phone, to deal with current fluctuation. Does it apply even if the device is turned off? The plan would be to trickle charge my phone, set to off, and to recharge my watch from the phone when needed
Probably. Phones can be pretty sensitive about the charge level they'll accept, and if your charger is providing too little current, the phone may just ignore it. It's more sophisticated and more finicky than hooking up a car battery to a trickle charger.