What battery to use with VNH5019 Motor Driver Shield

Hello, I bought a Pololu Dual VNH5019 Motor Driver Shield for Arduino 2507. The DC motor I am using requires 7.2V. What voltage and amp should I supply to the Motor Driver Shield? Are there any advantages or disadvantages of using higher voltage batteries such as 11.1V, 14.8V or 22.2V?

Hello.

If you want to supply 7.2V to the motor, you should use a power supply that can supply at least that much voltage. You should also make sure that the power supply can supply at least the stall current of your motor.

One of the advantages of using a battery with higher voltage is that you can get additional torque and speed. However, using a brushed DC motor at a higher voltage also shortens the lifespan of the motor. If you do use a higher voltage power supply, you can avoid shortening the lifespan of the motor by lowering the duty cycle of the PWM, effectively limiting the voltage applied to the motor.

- Grant

Thank you Grant. If I use a battery with higher voltage (e.g. 11.1V,14.8V), will the motor driver shield limit the voltage to avoid killing the motor? I guess a slightly higher voltage battery would allow the motor to generate higher torque but if the voltage is too high, it could kill the motor. I am considering two applications. In one application, one 7.2V motor controlled by one Motor Driver Shield. In another application, two 7.2V motor controlled by one Motor Driver Shield. What voltage and mAh of battery do you recommend in each case?

The answer depends on the motor stall current, the averaged expected motor current and the desired run time. What are those values?

I will check if I could get more info from the manufacturer. According to the advertised specs, the motor consumes a current of 1.2A when there is no load. As for the desired run time, 5 to 10 minutes. If possible, 20-30 minutes or longer. If possible, the weight of the battery be below 500g. The lighter the better.

OK. I got the data you requested.

・stall current...18A
・the averaged expected motor current...5A

Battery capacity is measured in ampere hours, or milliampere hours. It is only approximate so you should buy a battery at least twice as large as the estimated total energy consumption. 5 A for 10 minutes is 5/6 Ah, so 2 Ah or 2000 mAh should suffice. However the battery also has to deliver the startup current so the maximum discharge rate, measured in C units (capacity) is important. Look for a 2 Ah, 10C (20 amp) battery.

Thank you. So, anything battery with over 2000mAh and over 10C would be good? What voltage should I choose for the 7.2V motor in the following two cases?

a) One VNH5019 to drive one motor
b) One VNH5019 to drive two motors (is 2000mAH and 10C good enough)?

Hello.

The guidelines Jim provided for selecting a battery sound reasonable for one motor. If you wanted to run two motors from a battery with our dual VNH5019 motor driver, they will act as a parallel load and you will need a battery with the same voltage and the ability to provide twice the current.

If you want to understand more about how batteries are rated, I suggest reading the Understanding battery capacity: Ah is not A post on our blog. If you do not know the difference between wiring a circuit in series or parallel, the Parallel circuits post on our blog or an introductory electronics book might also be helpful.

-Nathan

[quote=“nathanb”]Hello.

The guidelines Jim provided for selecting a battery sound reasonable for one motor. If you wanted to run two motors from a battery with our dual VNH5019 motor driver, they will act as a parallel load and you will need a battery with the same voltage and the ability to provide twice the current.

If you want to understand more about how batteries are rated, I suggest reading the Understanding battery capacity: Ah is not A post on our blog. If you do not know the difference between wiring a circuit in series or parallel, the Parallel circuits post on our blog or an introductory electronics book might also be helpful.

-Nathan[/quote]

Thank you. Do you mean I have the following two choices:

  1. One VNH5019 for one motor case: Any battery with 2000mAh (or above) and 10C (or above).
    If I want to use two motors, just buy one more battery of this specs and one more VNH5019?

  2. One VNH5019 to drive two motors: Any battery with 4000mAh (or above) and 10C (or above).

Besides the cost and space, what are the advantages and disadvantages of using only one VNH5019 to drive two motors?

How do you intend to use two motors?

To make robot.

Then it should be obvious that two motor drivers are required.

Could you please let me know the reason? In the case of a big two wheeled robot, can’t I just use one VNH5019 to control two motors?

One VNH5019 runs one motor. You can buy a board with two VNH5019 drivers, for two motors.

Hello.

Just to clarify what Jim said, the VNH5019 is an integrated circuit designed to drive motors. This type of IC is generally referred to as a motor driver. We have integrated this motor driver into two of our products, the Dual VNH5019 Motor Driver Shield for Arduino (which you referred to in your original post) and the VNH5019 Motor Driver Carrier. The Dual VNH5019 Motor Driver Shield for Arduino has two of these motor driver ICs on it and can control two motors independently, while the VNH5019 Motor Driver Carrier has a single VNH5019 IC and will only control one motor independently.

-Nathan

Thank you. I have the Dual VNH5019 Motor Driver Shield for Arduino. In this case, is it advisable to use one driver shield (with two VNH5019 chips) to drive two motors? If I use one motor shield to drive one motor, I will need to get one more Motor Driver Shield for Arduino and one more Arduino to put on the same robot. Any advantages in doing that? In case I use just one Dual VNH5019 Motor Driver Shield for Arduino to drive two independent motors, what battery specifications do you recommend?

Hello.

If you look at the product page for the Dual VNH5019 Motor Driver Shield for Arduino you will see that this product can independently drive two DC motors. What specific benefit do you hope to get from using two of these shields on two different Arduinos?

The two blog posts I linked to on Thursday have more information about how electronics consume power and how you would select a battery. We have also offered you some guidelines here, but your follow up questions do not seem to follow logically from the advice we have provided. If you are still confused about selecting a battery, you might find it easier to get started with some introductory electronics project kits before attempting to build your own robot from scratch.

-Nathan

Hi guys,

Since using the wrong battery could cause life, I made some selections for you to double check. I plan to use one Dual VNH5019 Motor Driver Shield for Arduino to drive two motors with specifications mentioned before.

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hobbyking.com/hobbyking/stor … ouse_.html

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hobbyking.com/hobbyking/stor … ouse_.html

hobbyking.com/hobbyking/stor … ouse_.html

You have been given enough information and direction to make a reasonable choice, but if this is truly a life or death decision, drop the project immediately.