Accidently put the batteries the wrong way
 

Did I fry my bit? I was doing the dual mod, but didn't realize that the batteries were supposed to connect negative to positive, from the recharge tabs that connect to the pcb.

Now I can't seem to get the car to do anything. The car has a circuit now and I can recharge the batteries. Did I fry the batteries?

sounds like it to me......... lol

you can charge a battery with it now, but will the car run off of it? or did you fry the PCB also?

If you connected positive to positive and vice versa then you didn't increase to 2.4 volts, you merely doubled your capacity at 1.2 volts. You didn't fry anything, however you may have if you tried charging your dual capacity 1.2 volt battery with 3.0 volts (like you're supposed to for a dual battery car).

I recently had the same problem on a single cell bit. 2 clones had opposite battery positions and the batteries seemed to be fried. Charge the batteries individually, pop them out and connect them up to a volt meter. I found that the batteries werent damaged, but charging them "backwards" almost de-charged them. But shoconn is correct, if you hook the batteries together in series then you are not doubling the voltage, just increasing the run-time / capacity.

Later.
bitspeC

Actually that’s Parallel not series. Connecting them positive to negative (Series) doubles the voltage. Connecting them positive to positive (Parallel) keeps the voltage the same but increases the capacity.

Craig