just got a new 3905 E-maxx.

[suicideneil]

Geek, and crazy. What do you need the voltage regulator for exactly?

If you want to use A123s, then the best option for a stock emaxx is 5s, so a 3s and 3s pack in series; only when you start playing with BL setups do you need a pair of 5 or 6s packs in parallel (6s2p for example like yours truelly runs).

The 10.8v itsnt going to net you more than a snails pace top speed, unless thats what you want, and 7s3p of nimh cells is just daft- thats about 3lb of batts, one pack of which has nowhere to mount to (easily atleast).

You dont need to go crazy with weird electrical setups, follow conventional wisdom to avoid burnt fingers and electronics

What are your future intentions for this truck anyway?