I have hearing aids that have internal, rechargeable batteries. The charge lasts about 24 hours, and therefore the aids will not hold a charge from before Shabbos until after Shabbos. The aids are dropped into a charger for charging. The charging takes 3 hours. Is it permissible on Shabbos to put the aids in to the charger on a timer that turns on from 2am to 5am? The charger would be off when the aids are inserted and removed. If this is not permissible, would the aids have to be removed as muktza when the battery runs out?

Thank you for your question, Yes you could. (I'll 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 litte box. In that case a timer wouldn't help). All the best!