NeuEnergy battery tray ?

[BrianG]

The only additional problem with the notching idea is if using something like a Slash/Pede/Rustler/etc where the tray walls act as part of the chassis. For that, additional bracing would probably be the easiest, or arrange the cells on edge so the wires face upwards. Makes the COG a bit higher and requires some type of foam or something to fill the sides up to the walls though.