Phone's battery swells up when running automation 24x7

I am using an automation framework that includes appium and selenium for my tests.
Tests are running 24x7 on both android and ios.

My setup:
- Android and ios phones are connected to Mac Mini.

After a few months of usage I saw that the phone battery started swelling up and stopped working. I already replaced my phone twice.

Do anyone experienced this before? What can I do to prevent this?

Thanks

2 years. 10 iPhones, 8 Android phones. So far:

  • one android died motherboard (replaced by guarantee)
  • one android same battery problem (replaced by guarantee)

There are basically two things we were doing to avoid that:

  • Keep your test devices in a cool dry place, preferable a server room with temperatures between 16-18 Degrees celsius
  • Do not keep the device constantly connected to a power source. Of course this would be an impossible task without an automation. We were using Acroname programmable usb hubs, which could cycle usb power according to the given schedule.

In general, mobile devices are not created for this type of workload, and the best way to workaround the described issue would be to completely remove batteries from them and connect them directly to a power source. Although, it would be a completely different story. Also, some phones have special controllers inside of their batteries, so one would have to mimic these when using batteryless connections.