Stepper motor running off battery

Hi,

I'm trying to run this stepper motor (1A per phase, 16Ncm) with a battery—I have tried 9V, and two 9V batteries in parallel. I am using a DRV8825 driver.

I realise such a stepper will drain the batteries extremely quickly, but shouldn't it work fine until that point? Wouldn't the batteries provide as much current as was needed and then drop their voltage and die?

I have tried powering the stepper with a variable power supply at 9V and it works fine.

So my questions are:
-What am I not understanding?
-What kind of battery should I be using? (It needs to be handheld—small 12V battery, 8-pack AAs?)
-If this doesn't seem realistic, how much smaller should the stepper be for this to work?

I only need about 30min - 1h of use per charge.

Thank you in advance.

Alkaline AA batteries can supply 2 Amperes when fresh, and have about 2.5 Ampere-hours capacity, so they might last for 30 minutes or a bit more with such a motor. 9V block batteries are for smoke alarms, not motors.

If you set the current limit on the driver for less than 1 Ampere, the batteries will last longer but the motor will have less torque.

Small 9V batteries are designed for appliances with <50mA current drain, will typically handle 150mA briefly without horrible voltage droop, but 1A and they are completely overwhelmed. Batteries have internal resistance.

For high current drain use SLA, LiPo, LiFePO4 or NiMH. And read the datasheets. Yes batteries (the good ones) have datasheets. https://batteryuniversity.com/ is a good general resource.