"(Ill just mention that there are certain types of chargers that charge the hearing aid right when you put the hearing aid in the charger. these chargers come in a little box. In that case a timer wouldnt help)." Why would the little box be different? Specifically, the box needs to be plugged into a power source, and the box does nothing if not attached to power. If the power plug is plugged into a timer, wouldnt the result be the same and permitted?

Shalom, if the box does nothing when the aid is put in then it's fine. I meant that there is a certain aid box that's pretty common today that charges the aid when the aid is put in the box and turns the aid off when you take the aid out. If your aid is different, then it's o.k. The idea is that you cannot do an act that directly uses electricity. However, you may (in your case) do גרמא meaning an act that indirectly charges the aid. All the best!