DC motors run slow and weak. Can the culprit be the motor controller?

Question

I’m working on an Arduino car project. Here’s a diagram:

I am using an OSEPP motor shield to control 4 TT DC Gearbox Motors.

I am powering the motors using 4 AAs batteries, total 4.8V

The problem: the motors run slow and weak.

I believe the OSEPP shield uses L293D motor drivers and I understand these are inefficient.

Will using an Adafruit motorshield with TB6612 MOSFET drivers improve the speed and strength of the motors?

Thanks in advance!

Connect bateries straight to the motor and find out. But MOSFETs will be better just because you can make them bigger. — DKNguyen, Nov 04 '20 at 02:24
Dump the L293 shield and get the FET shield. Low side for PWM and high side for direction then consider 4.8 are near dead SoC voltage for Alkalines 4x 1.2V . it ought to be 4x1.5V= 6V or D cells — Tony Stewart EE75, Nov 04 '20 at 04:38
https://electronics.stackexchange.com/questions/108686/l293-l298-and-sn754410-h-bridge-drivers-on-low-voltage-power-supply — Andy aka, Nov 04 '20 at 09:41
the 1.2V are a typical value for NiMH rechargeable cells. four times that is a typical setup for RC equipment, while your motors might not be designed for the voltage range yielded by 4.8V minus driver drop.. — dlatikay, Nov 04 '20 at 15:57
Does this answer your question? L293, L298 and SN754410 H-bridge drivers on low voltage power supply — Marcus Müller, Nov 15 '20 at 22:30

ocrdu · Accepted Answer · 2022-08-16T08:38:46.173

9

Those are 6 V motors, I think (please check). You are feeding the motor shield with 4.8 V, and the not-very-efficient L293D will drop the voltage the motor sees by 1.4 V to 1.8 V, so you end up with only 3 to 3.4 V across the motor.

Using 4 primary cells of 1.5 V each, or 5 cells of 1.2 V each, should show some improvement, and yes, so would a more efficient motor driver; there are several options (that use MOSFETs) for that these days, and they will make a big difference.

You can experiment by connecting a motor to 4.8 V and to 6 V, both with and without the motor driver inbetween, and see the differences.

edited Aug 16 '22 at 08:38

answered Nov 04 '20 at 02:34

ocrdu

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I ended up swapping the old motor shield for the Adafruit Motor Shield v2.3 (https://www.adafruit.com/product/1438) and replaced the 1.2V NiMH rechargeable cells with 1.5V EBL AA Li-ion rechargeable batteries (https://www.amazon.ca/gp/product/B0891WB755/) -- the difference was night and day. Motors runs fast and strong now. Thanks to everyone who posted answers! – Marcelo Bursztein Nov 14 '20 at 16:55

DC motors run slow and weak. Can the culprit be the motor controller?

1 Answers1