I bought the recommended car charger from Sprint and it sucks. When plugged in, my phone drains almost as fast as if it wasn't plugged in at all. I have read that some chargers are much more powerful than others. What should I look for? Any suggestions? Also, I have this transformer thing that plugs into my lighter and has a regular AC plug outlet. Couldn't I just plug my home charger into that in the car and get as good a charge as at home?