Onboard Batteries for non-ROV device

Hei. Does anyone have any experience or ideas regarding onboard batteries for the non-ROV device? I would like to use a M100 motor with Basic Esc powerd from a 12V battery.
Restrictions: Non-rechargeble. Type: AAA, AA, A, A23, C or D alkaline batteries.
I tried with two parallell Batteri GoldenPower Maxi P+US Alkaline 12V 50mAh batteries. I ran the motor on a 1600 microseconds PWM signal wich sould have given me approx 1A. The voltage dropped from 12 to 7V instantly and i got only 0.2A. Appriciate any suggestions for batteries, what to look for when choosing etc.
Regards