I have a battery powered hotspot from my provider. Like a phone, it refuses to run off usb without a battery installed. But it yells at you and shuts down when

I have a battery powered hotspot from my provider. Like a phone, it refuses to run off usb without a battery installed. But it yells at you and shuts down when plugged in for too long. I need to have it online all the time. I "fixed" it by plugging the charger into an old school mechanical timer. Every six hours, it runs off the battery for 30 minutes. Has been working great for 2 years.