Why didn't my batteries get fried?

[joeNuggetz]

I have a 2 cell ZZ. I made a custom charger out of 3 AA Batteries. I usually charge the car for like 3 minutes. Anyway, since its a manual process, I put the car on the charger and forgot about it. I noticed that the car was still attached when the movie I was watching ended. It was on there for at least a half hour or more.

Well, I tried to race the car around and it worked. I even took a sniff to see if anything was burning. Nothing. Didnt feel any heat either. So I run the car around for a bit. 3 hours later, I try to run the car, and the damn thing was running as if I just charged it. Usually, any ZZ or bit that I charge and not use for a while looses all of its juice. I was suprised to see that everything was still good and that the car worked hours after the initial charge.

Anyone know why this is? BTW, I'm using 2 stock ZZ batteries in the ZIP and like I said, 3 duracell ultras in my custom charger.

Thanks