Ni-mh packs will only give enough if you choose the right brands and capacity range.

I personally use 3300mah GP cells on my featherweight, and so do many other people. GP cells are one of the best Ni-mh cell types around and far out-perform standard Ni-mh cells.

3300mah ni-mh cells may not be enough for 2 EV warriors though- as the tracks will probably cause them to draw a large amount of current- depending on the gearing you use. If you can get packs bigger than 3300mah, then great, but be aware that they may not perform as well as smaller yet more expensive cells.

Should you need to source extra-large amounts of current, ni-cad cells will have to do. Sanyo are usually best. You should be looking for 3000mah minimum ni-cad cells.