My daughter has a light up mirror with a 12v DC adapter, but also appears to be battery operated.
It broke, so I've opened it up and saw what I think is very strange wiring!
It has a standard 3.7v li-ion battery with its own DWO1 protection circuit, however it's directly wired to the 12v barrel jack (!?!)
Putting aside 12v going into the 3.7v li-ion for one moment, the wiring of the circuit seemed weird to me as both the 12v DC and the battery output that powers the little light control PCB are both wired to the same P- and P+ points on the protection circuit. I thought I'd measure the volts directly on the P- and P+ points ,while 12v DC is connected, to see what was being output, but it would only read the battery voltage of around 3.2v!
As you can see from the photos, I'm essentially putting my multimeter on the red and black wires that come directly from the DC barrel jack so where has the 12v gone?
I hope that makes sense! Please help, this is driving me crazy!
(Spoiler, I've removed the battery and 12v dc, and converted the mirror to 5v USB)