iPhone X Do they make a device that keeps the battery of a backup phone from dying when not in use?

[TH55]

I have heard that letting a battery completely discharge quickly accelerates the life of the battery and is very bad for it, is there a way to prevent this for a phone you seldom use?

I have an iPhone X that I use as my backup phone for kayaking, and with the season ending I’d like to keep the battery from staying dead all winter. I know motorcycles have things that can maintain a charge on the battery to prevent this, surely there is something for a small phone battery. Thanks!

 

[minimo3]

Turn it off - as in full shut down. Then set an alarm to charge it every 3-6 months. When I power mine on every few months to charge up they still have more than 50% batt left (during the full shut off period)

 

[now i see it]

You can get a HomeKit compatible smart plug (Eve makes one available from Apple) and set up a battery charging automation in the Shortcuts app to keep the battery charge between 40% and 50% automatically forever. When the battery drops below 40%, the smart plug will kick on then turn off at 50%. Etc.

Only problem with that setup is the phone has to be left on.

The phone uses battery power even when on the Lock Screen, but keeping the charge level so low and automatically topped off won’t degrade the battery significantly.

Personally- I’d take the advice above and turn off the phone completely at 50% charge level and just set an alarm reminder to check it every month or two.