regarding internal, non-removable, rechargable battery hearing aids, which are charged wirelessly (no electrical contacts) by setting them in a desktop charger. the battery of the hearing aids lasts for about 26- 30 hours on a full charge. This would normally be suffiicient for a single day Yom Tov or Shabbos. When there is a double day situation, is it possible to place the hearing aids in the desktop charger when it is disconnected from the electric (by a shabbos clock) before the hearing aids battery is completely finished – to have the charger turn on at a later time and then turn back off (by a shabbos clock). And then when the charger is turned off, remove the hearing aids for continued use?
There is some controversy about this, however there are poskim that you can rely on to do this. Obviously, the clock will be set from before Yom Tov, with all the conditions that you mentioned.