[kllrnohj]

The heat isn't too hard to deal with, there are solutions (including the weird ones like water cooling cases https://www.ebay.com/itm/175003613243 ). Simply adding airflow tends to get you pretty far by itself, even. Device test labs are a common-enough thing and handle running phones like servers at scale without too much difficulty.

But there's more nasty lurking problems in this area, like that phones aren't designed to be continuously powered. They will naively try to keep the battery at or near 100% charge, which will destroy it relatively quickly, and not uncommonly in the "it's bulging and increasingly likely to burst into flames" variety. 2 years is considered a "decent run" for things like device test labs as a result (see eg the FAQ on https://github.com/DeviceFarmer/stf )

[jdboyd]

It seems that putting a timer on the power source (set to say 30 minutes on, 30 minutes off if the load justified it) would be a fairly simple way to significantly extend the battery life. I've been thinking of putting together something like that for myself to charge a bank of test phones for 30 minutes twice a day.

[kllrnohj]

I'm not sure it would. What would extend it is if the phone could just pull from the wall directly & not the battery, so the only charging / discharging the battery gets is from being unused & slowly re-topped back to 80-90%.

If you do your timer idea it seems like either you're going to be hitting it in the 80%+ recharge over & over & over again, which doesn't seem meaningfully different from leaving it plugged in? Or you'll be in the sub-80% quick-charge zone, which will destroy the battery even quicker.