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I’m working on an Arduino car project. Here’s a diagram: enter image description here

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!

Marcelo Bursztein
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    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
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    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
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    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
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    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](https://electronics.stackexchange.com/questions/108686/l293-l298-and-sn754410-h-bridge-drivers-on-low-voltage-power-supply) – Marcus Müller Nov 15 '20 at 22:30

1 Answers1

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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.

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