Rich I don’t know for sure because I’ve only had a new phone for a few weeks and haven’t paid much attention to the charge on the old one.  My guess is 2-3 days. I’ll do some experimenting and let you know. But yes, it’d need to be charged regularly even when switched off. 

The FindMyPhone App (on my active new phone) does keep a record of where & when the other devices on my Apple Acct last ‘pinged’, even if their battery is currently flat. 

Yes those little hearing aid size batteries do last well. They are same model battery which power my CatEye bike odometer, and they are surprisingly durable.

Kelly yes it’s a useful, coincidental feature. The other, main use of the unlocked old phone (when travelling overseas) is fitting it with a local SIM and re-using it as a phone. 

On a recent, short trip to UK/Europe the ‘overseas roam’ service of my usual service provider simply wouldn’t work.  This was the first time it’s failed in numerous trips. I got by on WiFi, but on future OS trips I’ll buy a local SIM and use my old phone for comms. It won’t only be a back up tracking device. That’s a useful by-product. 

Hi Steve, Android does indeed have a Find My Device app available in the Google Play store. It worked beautifully recently when Jen lost her phone in Colorado. 

Rich my old, simless iPhone (an 11 max) retains charge for about 4 days when switched off but still emitting a blue tooth signal detectable by the FindMyPhone app on my new iPhone and mini-iPad. 

Thanks for testing that, Graham.   There are definitely some cases where I can see that being useful!

I think Android’s Find My Device feature only works if the device has a Wi-Fi or cellular data connection. It doesn’t work like Apple’s Find My where it reaches out via Bluetooth to any nearby iPhone to report its location. But I’ve read that Google is working on rolling out a similar feature. Or maybe they have by now.

Ahh, I see. That sounds right.