Two stepper motor with A4988

[Riqo]

Hi, I have two Hybrid stepper motors with about 2.7V, 1.68A connecting with a Raspberry Pi. I have 2 concerns.

1) I am designing a portable device therefore in the field there is no fixed power supply. So what kind of external battery is best suit for this?

2) I am running headless. Its all fine when I test with a single motor, but once i start to connect with 2 steppers, Putty can't run. I am not able to log in. Need help pls

[mwrich4]

it sounds like your supply can't give the RasPi what it needs when both motors run. Perhaps a reasonable capacitor might help if the batteries don't have a high peak current output. Single AA's seem to give about 4A in a short (20A range on multimeter)

Make a little monitor circuit that flashes an LED from the Pi at a human rate. If the light stops, the system has crashed.

[HermannSW]

2.7V, 1.68A is 4.536W, Pi4B needs 3A, 5V or 15W, so in total 15+2*4.6=24.2W.
With motors I would always go with lipos, use >=2 cells lipo with one step-down converter to 2.7V for the motors and one step-down converter to 5V for the Pi.
A lipo with 1000mAh and 25C and deliver 25A maximal, there is no limit.
I recently bought 4S 1300mAh 95C lipos, they can deliver 123.5A max:
https://www.raspberrypi.org/forums/view ... 0#p1633505