It's pretty easy (at least for single devices) to use a timer powerpoint switch and guess/tweak an appropriate duty cycle to keep the battery topped up often en

It's pretty easy (at least for single devices) to use a timer powerpoint switch and guess/tweak an appropriate duty cycle to keep the battery topped up often enough without leaving it charging 24x7. I have an old iPad that's been running for 5+ years with 1hr/day charge time. (I cooked it's predecessor's battery to a screen-cracking-bulge in about 9 months.)