My wife (samsung fascinate with 3500 battery) and I (Dinc with 3000 eBay battery) used both recently on a trip. Even plugged into car charger, the phone seemed to use more power than the charger could supply while using Navigate. Would turn off navigate after reaching our destination and even though plugged into car charger, the batter was lower than it was to begin with. Both phones also got extremely hot. My wifes Fascinate would just shut down, but my Dinc kept working, even up to 127* showing on the battery widget!