The main issue is that you are using low quality, machine assembled, NICD cells. The Elite 1500 2/3 A cells are NIMH cells.
I run a 8 cell pack of 2/3 A Elite 1500's on my rig and average 40 minutes of run time running duel 65t lathe motors.
Upgrade to a pack from Holmes Hobbies (
www.holmeshobbies.com ), or
www.cheapbatterypacks.com .