I do lots of testing of apps in real phones, not emulators.
The thing is that the phones must be connected to the PC all day. Because of this, phones battery get swollen and I have to buy phones regularly.
Do you know any android phone which can be connected and on all day all week without getting swollen after a time?
Must be real phones, emulators are descarted.
Not likely as a swollen battery is a sign of a fault happening but not catastrophic yet.
Another option is a phone with a replacement battery so if the battery goes switch the battery and keep the phone going.