Replace/upgrade the current battery pack with accumulators that can be charged by USB (USB-3).
Features
The new battery pack would have the same dimensions. But it would have as well a power input (even better several: USB micro, USB-3, maybe lightening) to recharge it. Users could use another power bank to charge it “overnight” by just hanging the power bank to the door handle. No need to take it out, to remove the battery pack.
Reason
ease of use: no need to remove the battery pack
environmental friendly: no need to use batteries
reducing the risk of low battery
an embedded power bank might be more powerful than rechargeable or single use batteries.
Examples
included into new future SmartLocks
to be bought as additional device, for people who would prefer to charge the “new power bank” at a plug.
This is nearly the same I defined in USB Battery Case Dummy
A complete Powerbank with the measurements of a batterycase wouldˋt be possible imho, therefore I just thought of an internal capacitor.
To Carsten, sorry as well, I had not seen your post.
I would prefer not to have to add an external powerbank to the system all the time. But just a USB-plug to recharge whatever battery (AA or maybe a LiPO4 alternative) without the need to remove them. It can be done on the fly over night.