Problem with lack of torque from stepper motors

hey driving device using 2 stepper motors , motors slipping point wheels dont rotate. stepper motors im using have 48 n.cm holding torque rating , 1.7a/phase , using big easy driver ramped full 2a/phase drive them. using 2 9v in series (18v) power them. there not enough current being supplied or option decrease radius of wheels reduce torque on motors?

don't offended using 2 pp3 9v smoke alarm batteries in series , being surprised you're not getting 1.7a ludicrous.  you don't have chance in hell of getting 1.7a out of smoke alarm battery if life depended on it. can throw in trash right , start looking replacement because never had chance begin using those. short answer why internal resistance high. need lipo batteries  a 4s lipo give maximum torque possible  the 1 linked below 1 of cheapest because 2200mah means 2 x 1.7 = 3.4a , 2.2ahr/3.4a = 0.64 hours = 38minutes of use on full charge.

be sure use genuine lipo battery charger , never charge lipo battery unattended because can burst flames if overcharged , why need lipo charger. never charge lipo battery on surface can burn .(meaning must in ceramic pot or metal box or concrete or brick barbaque pit never on wood).

http://hobbyking.com/hobbyking/store/__9943__zippy_flightmax_2200mah_4s1p_40c.html  
 http://hobbyking.com/hobbyking/store/index.asp

Arduino Forum > Using Arduino > Motors, Mechanics, and Power (Moderator: fabioc84) > Problem with lack of torque from stepper motors

arduino