Trickle power to ramboxe et al

[PeterP]

Inspired by Diego’s USB cables to power the HP41 i was wondering if something similar could be built to provide a rambox with a trickle power to avoid the internal buffer battery going dead. I have a number of them in my display and would love to find a way to power them discretely - like a plug similar to that PCB in the Clonix programmer - connected to some USB like power so it retains the OS.

Now I’m concerned about plugging a USB connected PCB into a rambox directly given it provides 5V as if the calc is turned on. Or am I overthinking this? How would the EE geniuses here solve this elegantly? Ive got 2 weeks at home with no where to go and need a good reason to tell my kids that I’m busy with something incredibly important at least some part of the time...