Car charger question

[Guest chrisdealb]

I've got a usb car charger lying around, specification: 5V 850mA

Before risking a test, I was just wondering whether this will be ok to use for charging my touch dual? The mains charger is 5V 1A, so not identical, hence I'm a bit apprehensive.

If anyone who knows a bit more about these things could give me a bit of insight it'd be much appreciated.

Thanks in advance!