[Axel]

Oh, gotcha :-) I haven't actually used parallel yet. I did hook it up though, and there was only a very slight mA increase at the engine and .1 voltage increase over stock (could have been due to fact that these were just fresh batteries). While it lasts a lot longer, I doubt by the readouts there that it would make anything faster. It would probably slow stuff down (extra weight).

ya, I did that and found which battery isn't charging...but I don't know why it's not charging. The circuit is setup fine and it works by itself if I revert to stock setup (no dual battery). Weird, huh?
And not only does one battery not charge, but it pulls voltage and mA's off of the other battery, so it ends up that I only get like .5v and 50 mA at the motor.

I can still take both batteries out and recharge them separate and then hook back up and it zooms at 2.4v for a while (actually 2.2 to the motor was what I was getting) and then both batteries die, I recharge through the car, and only one battery recharges again... whichever one has the positive lead connected to it. can I run a positive from the charger to both batteries while in the car without screwing up the parallel/series thing, any way that you know of?