Is this normal? (newbie question)

[WSPFreak]

Hello,

I am new to these micro rc's and I got a ZZSE Viper for X-mas. When I first put the thing together, it ran for a good 6-7 minutes, with the lights on. Now I only get about 2 minutes of runtime, and I have only had this thing for a couple of days. My brother also got one, I believe it is the Corvette, and his is still running about 6 minutes on one charge. I've read some other posts, and bought brand new batteries for the controller, and I am getting the same 2 minute runtime, sometimes less. My question is should I only be getting 2 minutes of runtime, or could there be something with wrong with the batteries in the car? I apologize if this is a common question, but I have checked several forums, and haven't seen to find any answers.

Thanks