12v Battery Monitor
Monitor your car's 12-volt battery... while China monitors your location
I'm no longer recommending this hardware for security reasons. Read below.
See it on Amazon UK
See it on Amazon USA
See it on Amazon Germany/EU
Edit on 5th June 2024: I had a comment on a video from someone saying they've sent the hardware back to Amazon because Norton on their iPhone warned about the app. It turns out the app is sending anonymised location data to servers in China/Hong Kong.
There's an in-depth article about it here.
I believe it's very common for the Chinese government to insist on companies collecting data like this but I feel particularly uneasy about it.
I've kept the links on the page if you don't care, but personally I'll be looking for alternatives that have far less dubious security.
These are affiliate links so I'll get a little money if you buy using them. Thank you!