iPAQ 4100 charging problems with USB car charger

[smart_arts]

I cannot seem to get my 4100 to charge via a usb car charger (the guy I bought both of them from says it is the correct charger - HP brand MODEL USB-CLA - output 5.5Vdc: 700mA)

if I set my PPC in the charger whilst switched off and then connect the charger (the red light comes on the charger) the PPC automatically switches on so it seem to be getting some sort of current - but the charging LED does not flash and the battery does not recieve any change in power level

[DrAT]

My hx4700 won't charge via USB unless this is enabled under 'Settings/Power/USB Charging.' I use the fast charging setting.

[smart_arts]

My hx4700 won't charge via USB unless this is enabled under 'Settings/Power/USB Charging.' I use the fast charging setting.

I don't have any "USB Charging" option under setting/power ;-((

[Nurhisham Hussein]

If you have a multimeter, you might want to check out whether then charger is actually giving out 5.5V, 700mA. It's also a possibility that your car battery isn't giving enough output either.

[DrAT]

Sorry about that. Your iPAQ doesn't have the USB charging applet.
As mentioned above, it would be worth checking the output of your charger. Problems can also arise when trying to charge a nearly flat battery via USB.
HP released a ROM update (1.10) for the 4100. One issue addressed was 'USB stability.' Could this have anything to do with your problem?