My son and I both have the HTC Thunderbolt, and have both experienced the same issue with the battery drain after using the Verizon car charger. Each and every time after the phones have been plugged into the car charger, the phones well get about 2 – 4 hours of stand by life MAX. Both phones get very hot and the battery is almost to hot to touch. This happens every time we use the car charger. If after using a car charger you remove the battery and reinstall the battery the phones will now get at least 8 hours or better of standby life. I repeat this happens to both phones EVERY time we use the car charger.
Almost forgot to mention that I used two different car chargers as well.
I have to believe this is a safety issue and that Verizon needs to look into this issue ASAP.