This Anker charger solved it.

It gives a steady 1000mA that is enough to charge and use GPS.

I have to give a huge thumbs up to Anker, because together with the car charger i also bought the Astroslim 3 6000mAh powerbank, which charges two devices the same time, at a steady 1500mA each!!! I loved bothe the car charger and the powerbank, definitely worth their money.
2004-2010: Windows Mobile - 2011 and on: Android