USB device with battery

[Corky34]

My google-fu has let me down so hopefully you guys & girls can educate me.

It maybe a dumb question but if you charge a device, like a game controller or torch, from a USB port on a PC and leave it connected after you've shutdown the PC and then turn it off at the wall does it drain the battery? My first assumption was no but i noticed when everything is powered up the following day the charging light lights up for a good while so I'm wondering if my assumption is wrong.

[jimbouk]

You'd hope no - I'd assume the 'charging up again' was due to the charging circuit in the battery not being that smart and just happily trying to top up a full battery. They should at least have a diode in them though!

[BobF64]

Batteries naturally drain, even when a device is "off", but over night i wouldn't expect a lot of drain.

Logically, the way to test this is to charge the device fully, this time unplug it over night, then plug it back in the next day, does the same charging happen?

[Corky34]

Thanks for the advise, my main worry was that i was doing something wrong/damaging by not unplugging USB devices with batteries in them.

I'm going to do some testing like you suggest BobF64, I'll use a stopwatch to see what the difference is with it being plugged in and unplugged, not that it's all that important if no damage is being done by leaving it plugged in, it will just be interesting to know.