Does anybody know about Motorola chargers (or usb charging in general)?

[DrkLrdsSlv]

I've got a motorola q9c which charges via usb (but only with a special windows driver) or via a wall wart. It uses a mini usb plug.

Now I recently had my secondary tag-along charger die and quickly ordered a cheapy from amazon. But, apparently my phone only likes OEM chargers, because it refuses to charge with this new one

Suspecting it may be due to the lower amperage of the new charger (450mA vs 550mA), I ripped it apart and frankensteined together a new charger out of old parts, which output up to 1000mA. And once again, no dice. One thing I noticed from the cheap charger was that only 2 pins were used from the usb cable - +5vdc and gnd.

What exactly makes the OEM charger "special" so that my phone will accept current from it?

 

[vgta88]

i think they have a proprietary usb connection. like its wired differently not how much amps its outputing. thats how the razrs were. I think they needed to send a signal to tell if it was a usb headset or a charger.

 

[AlexanderB]

the original one has a tiny resistor in the phone connector.. its wired to the normally unused pin of the usb connector (theres 5 pins in the mini and only 4 in the normal one..)

the other way around would be firmware-modding the phone to charge from any 5v source, this was very easy to do on the razr's dunno about your phone tho..