I have a sportswatch which can be connected to a PC via USB for downloading the training information, upgrading the firmware, etc. I have used those features for a year on weekly basis, but since today, kernel does not register the watch and Linux ring-buffer logs following if I connect the watch:
[772682.440095] usb 1-3.1: new full-speed USB device number 36 using ehci_hcd
[772682.848050] usb 1-3.1: device not accepting address 36, error -32
[772682.920092] usb 1-3.1: new full-speed USB device number 37 using ehci_hcd
[772683.328030] usb 1-3.1: device not accepting address 37, error -32
[772683.400094] usb 1-3.1: new full-speed USB device number 38 using ehci_hcd
[772683.472094] usb 1-3.1: device descriptor read/64, error -32
[772683.648094] usb 1-3.1: device descriptor read/64, error -32
[772683.824096] usb 1-3.1: new full-speed USB device number 39 using ehci_hcd
[772683.896093] usb 1-3.1: device descriptor read/64, error -32
[772684.072094] usb 1-3.1: device descriptor read/64, error -32
[772684.176098] hub 1-3:1.0: unable to enumerate USB device on port 1
I have tried with different computers and reset the watch to factory state, but this has not helped. As a last resort, I would try to drain the battery of the watch. As seen on the picture below:
..it uses TA type screws in a deep sockets and I do not have a screwdriver for those, i.e. I can not simply remove the battery. In addition, during normal operations, the watch will go to some sort of standby mode in case the battery is very low and it could stay there at least for days.
Has anyone drained Li-Ion battery by connecting the USB +5V and GND through a resistor? Is there a risk that Li-Ion battery will get so drained that later it will not start charging anymore?
Best Answer
There's two answers to this question:
Can it be done?: Probably not. Or in fact, very most likely not. To be a USB compatible portable device it has to not impose any voltage on the power pins by itself, unless triggered to be in host mode, which your watch very likely cannot do, because that mode was not designed into it. So you cannot access the internal battery through the USB pins.
Should you do it, even if you could? Again, probably not. If the battery is well protected internally it should be possible to drain it to a switch-off moment without causing deep-discharge and damage. But you do not know how well the battery is protected at the point your are "tapping" it. Maybe all the protection, not only sleep, but also safety switch off, is inside the watch's processor. Then tapping the battery directly will not include that safety and you can drain it to death.
Or to summarise: If you absolutely must, try getting the screwdriver, but since you don't have it already I might think you're better off taking it to some other place to be serviced.