Using 2xL298N to control 3 DC Motors and Components Compatibility!

Projects General Guidance
1

Hello!

I'm working on a project for my Software Engineering Class. My Group Mates and I are assigned to do a Forklift using Arduino with other components/materials... All of us have already heard of Arduino before, but we've never used it, so… we began doing a research to collect some ideas to work on and it lead us to this:

A simple wheeled boxed frame with ''basic'' movements, e.g.: forward/backward, right/left. It should lift up and down to about 1kg objects (or even lower). It's basically a standard forklift without worrying about aesthetics. Our goal is to make something like this, in terms of functionality (I don't know if I can post external links, if not, sorry):

*About the video: Our Fork Carriage will just go up and down when lifting the objects, it won’t make these complex movements such as moving sideways. The rest should be pretty much the same.

Our idea is to use 2 dc motors for the truck movement, controlling both motors individually, each one attached to one rear wheel, spinning them in the same speed when going forward or backward, and when moving to right or left the wheel on the opposite side of the turn (turning left -> opposite side is right...) rotates clockwise and faster than the other wheel rotating counter-clockwise. E.g.: I want to turn left, so, the right wheel rotates clockwise with high speed, and the left wheel rotates counter-clockwise with less speed than the right wheel.

A 3rd dc motor will be used to control the Fork Carriage movement, rotating clockwise or counter-clockwise to lift up or down the objects. We also have planned to control the forklift with a Smartphone via Bluetooth because this method seems to be the easiest to control the forklift without using any cables to send data/commands.

We have some doubts about controlling these 3 DC Motors individuality. We initially thought of using two L298N Motor Drivers to control them, in which one of the L298N would be used to control 2 DC Motors (Forklift Movement) and the other L298N would be used to control the DC Motor of the Fork Carriage Movement. Our question is: Is it actually possible to control 3 DC Motors with 2 L298N Motor Controllers? If the answer is ‘YES’, then, we would be grateful if you guys give a look on the Schematic/Circuit we’ve made that’s attached in this thread.

Some previous replies already addressed my doubts about the use of 2 L298N, and, as they said, this chip won't be enough to handle the DC Motors. We've researched a bit more and we found out a Motor Shield and a Module that fits our budget, we can find it supposedly easy and fast (needs to be fast because we just have 11 days to finish this project).

Motor Shield: VNH2SP30 Monster Shield and Module: VNH2SP30 Monster Motor Module.

The Shield would be used for the 2 DC motors that moves the Forklift and the Module for 1 DC Motor that controls the Fork Carriage's Lifting System. __*__What do you guys think about those components? Can they be used together with the Arduino UNO and running those 3 DC Motors? Bearing in mind that we don't need a Formula 1 car, just a normal (a bit slow) Forklift that can lift objects up to 15cm +/- above the ground, and that is able to move through places with some load in it without any problems.

With all that said, I'm going to write down below which components we’ve planned to use on the project (edited):

  • Arduino UNO

  • 1x VNH2SP30 Monster Shield + 1x VNH2SP30 Motor Module (1 dual ch + 1 single ch, replacing
    2x L298N) (Is this enough? Previously was 2x L298N)

  • 3x DC Motors with Reduction Gear Box(Same as before, just added + info)
    • Rated Voltage: 6v-24v
    • Nominal Voltage: 12v
    • Free Load Current: 430 Ma
    • Free Load Speed: 83 RPM
    • Max Continuously Output/Under Load: 1.6A
    • Max Under Load Speed: 65.4 RPM
    • Max Under Load Torque: 11.1 Kgf.cm
    • Max Under Load Power: 5W
    • Starting/Stall Current: 6A
    • (As already mentioned, 2 Motors will be used for the Forklift's Truck movement and 1 Motor for the
    Fork Carriage's movement)
    • (Can we possibly change the DC Motor of the Fork Carriage to a 360º Servo Motor using less weight
    requirement?).

  • 1x HC-06 Bluetooth Module

  • Power Supply (We’ll write down below a little more about this):
    • We don’t know for sure what kind of power supply we should use to maintain our setup, bearing in
    mind that the components won’t will run at full power all the time, just when needed. We want
    something cheap and compact, because our rig will have about 20cm x 30cm of length and this is why
    we chose some AA Batteries, we can’t afford to buy and use something big and over-powerful like a
    Car Battery. We’ve seem that there are some projects with two 12v DC Motors making use of AA
    Batteries or Rechargeables, and this lead us to think that the same thing could work in our project.

• Maybe a 9v Battery or 4~6 AA Batteries for the Arduino + a Power Bank with 10000mAh 5V, using a
Voltage Converter to 12V for the DC Motors?

Summing all this up:

1. Is it possible to use 2x L298N simultaneously? If it is possible, then…

2. We want to know if the components that we choose to use are compatible, especially the Motor Shield/Controller and the Motors, because the current of the motor when starting is 6A. The Shield and Module can be used in parallel with Arduino UNO both to control those DC Motors?

3. Are those AA Batteries and Power Bank enough to supply our Arduino, boards and motors? If not, what kind of power supply would you recommend? (must be cheap, we can’t afford to buy anything expensive, sorry).

4. Are there better electronic component options that’s easier to manipulate that we could use to control our motors and the Forklift itself? (We are from Brazil, we’re limited on the variety of components and they’re also a bit expensive to us and we also don’t have time or money to order them from oversea).

5. Can we build a Forklift that works properly with all these components or do we have to order other electronic components?

Bearing in mind all the things we’ve written here, and that we are just rookies, we would gladly accept your suggestions and effort to help our little project. Again, sorry for the long thread, our goal is to give as much information as possible to demonstrate what we hope to accomplish.

Any help will be appreciated and thank you guys for your time!

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2

Many issues here.

  1. you try to run 3 DC motors, each rated 1.6A under load, 6A when stalled (stall current should be the same as startup current).
  2. you try to do that using L298 motor drivers that are rated 2A peak, while requiring a pretty big heat sink to even do half.
  3. you try to run that off a handful of AA batteries.

First thing to do: see if that motor of yours (note that higher voltage means higher current!) can even lift that 5 kg load. I wouldn't be surprised if they're not strong enough to do this with reasonable speed.

Similarly: make sure those motors are powerful enough to move your whole rig - easily 10-20 kg, if not more with motors and gears and proper battery and whatnot - at a reasonable speed. Again, the specs don't sound too promising.

Then: find a proper motor driver. Not an outdated one like the L298. Something that's at least a bit modern, and that doesn't drop 2V (that's where all that heat comes from). A motor driver that can supply the stall current.

Finally: get a proper battery. A car battery comes to mind. 12V output, and lots of current available.

3

L298s will not drive those motors at full power. Three of those motors will not run well on a set of AA batteries. One of those motors will not lift 5kg.

If you want to use that equipment I think you will need drastically change your requirements.

Steve

4

slipstick:
One of those motors will not lift 5kg.

Add enough gearing and it will. It may just take half a day to get the load to the desired height.
Just the other day I was playing with a stepper. Takes only 100 mA at 5V, but no way you're going to stall it by grabbing the shaft, which is quite easy with ungeared motors taking much larger current. It's max speed of about 20 rpm won't get you anywhere fast, though.

5

wvmarle:
Add enough gearing and it will. It may just take half a day to get the load to the desired height.
Just the other day I was playing with a stepper. Takes only 100 mA at 5V, but no way you're going to stall it by grabbing the shaft, which is quite easy with ungeared motors taking much larger current. It's max speed of about 20 rpm won't get you anywhere fast, though.

Perhaps I should have mentioned that I was thinking practically rather than in a pedantic purely theoretical manner. But of course you're right with enough gearing and no requirement to get the weight to any reasonable height in a single lifetime almost any motor could do it provided you can get it run for long enough.

I'll give up trying to help. It's just not worth wading through all the resultant...

Steve

6

Thanks for the fast reply. The first thing we want to say is that we are flexible on how much
weight it can carry or lift, giving us more freedom on how to proceed with our project, that’s
why we chose to get a base on a project like that one from the video linked in the main thread.

wvmarle:
First thing to do: see if that motor of yours (note that higher voltage means higher current!) can even lift that 5 kg load. I wouldn't be surprised if they're not strong enough to do this with reasonable speed.

Similarly: make sure those motors are powerful enough to move your whole rig - easily 10-20 kg, if not more with motors and gears and proper battery and whatnot - at a reasonable speed. Again, the specs don't sound too promising.

• Hum, that’s a problem, because we might’ve misunderstood how the torque power of our
motors works with how much weight it could carry/lift. We still don’t know what specs the
motors should have to lift a certain weight, in this case, with a speed of 4 cm/s (0.04 m/s) +/-
or carry/move in a speed of 0.1 m/s (Yes, it’s a bit slow, but we assumed that a Forklift don’t
lift things in high speed neither moves fast, because this could lead to problems), taking into
account what you and the others have said, we’ll probably lower the requirements of weight
that the Fork Carriage lifts to about 1Kg max (or even lower than that) and for the Forklift,
assuming rig + load, would be about 3Kg max (or even lower than that if necessary).

• We’ve planned to build our Forklift similar to the one in the video that we linked. It doesn’t
need to be heavy or big… it’s just a project for quick demonstration, so, as we have mentioned
above, we can and will lower the requirements as soon as we discover what specs the motors
should have to run properly.

wvmarle:
Then: find a proper motor driver. Not an outdated one like the L298. Something that's at least a bit modern, and that doesn't drop 2V (that's where all that heat comes from). A motor driver that can supply the stall current.

• Yes, we are now searching for a better one that fits our budget, because as mentioned before,
here in Brazil the limitations are real, both in price and variety of components.

wvmarle:
Finally: get a proper battery. A car battery comes to mind. 12V output, and lots of current available.

• Yes, sir. We’ll definitely try to get a better one that fits our project. We have a Power Bank with
10000mAh 5V, using it with a Voltage Converter to 12V, do you think that’s enough for the
motor’s power supply?

• What do you suggest for us to use in order to match our requirements? We want the Fork
Carriage to lift up to a height of 20 cm +/-.

• We’ll keep updating this thread as we research and learn more about it, please, keep helping us.

Finally, but not least, thank you for your time, we really appreciate it!

7

Thanks for the fast reply.

slipstick:
L298s will not drive those motors at full power.

• Yes, for what we’ve read in some replies, they don’t.

slipstick:
Three of those motors will not run well on a set of AA batteries.

• What do you suggest for running those 3 Motors?

slipstick:
One of those motors will not lift 5kg.

• Why can’t the motors lift 5kg? Could you explain to me?

slipstick:
If you want to use that equipment I think you will need drastically change your requirements.

• Yes, we’ll probably lower the requirements, as we’ve said to 'wvmarle'. We have freedom
in terms of how our project works, so, we think about reducing the weight required to lift to 1Kg (Or even
less). We want to lift objects about 15cm +/- above the ground.

8

KuroG:
• Yes, sir. We’ll definitely try to get a better one that fits our project. We have a Power Bank with
10000mAh 5V, using it with a Voltage Converter to 12V, do you think that’s enough for the
motor’s power supply?

No chance. A typical power bank can supply no more than 2A. Then you convert from 5V to 12V, at an optimistic 90% efficiency, so that 5V 2A becomes (5/12) * 2 * 0.9 = 750 mA max.

For your motors: rig it up in a simple lift mechanism, with gearing to get to the speed you want, see how much it can lift. Then scale to the desired weight. Then double that required power, as you don't want to run a motor at its limit. That should give you a good measure of the required motor. Get one that has at least that calculated torque, and try again.

For batteries, you can also consider a Li-ion battery bank. Get a few 16850 batteries, they're good for several amps, four of them in series give your 13-16V depending on charge level. Consider using a separate battery for your logic parts, or a buck converter to produce the 5V you need.

9

wvmarle:
No chance. A typical power bank can supply no more than 2A. Then you convert from 5V to 12V, at an optimistic 90% efficiency, so that 5V 2A becomes (5/12) * 2 * 0.9 = 750 mA max.

Ok!

wvmarle:
For your motors: rig it up in a simple lift mechanism, with gearing to get to the speed you want, see how much it can lift. Then scale to the desired weight. Then double that required power, as you don't want to run a motor at its limit. That should give you a good measure of the required motor. Get one that has at least that calculated torque, and try again.

• Hum, we’ve been reading some articles about what specs are needed to lift X weight in Y height and we
discovered that there are some calculations to make. As we don’t have the motors yet, we'll try to get the
power, torque and speed required from those math formulas. After that, we’ll double the required power like
you said. Thanks for the advice.

wvmarle:
For batteries, you can also consider a Li-ion battery bank. Get a few 16850 batteries, they're good for several amps, four of them in series give your 13-16V depending on charge level. Consider using a separate battery for your logic parts, or a buck converter to produce the 5V you need.

• That's it, you gave us a reliable option for the batteries, because here the 18650 (we didn’t find the 16850
ones) is very affordable in pricing (if we search for the right ones and not scums). Check this out: 4x 18650
Batteries with 3.7/4.2v and 2200mA+, in series, would they be enough?
About the logic parts (I assume they are the Arduino and Bluetooth Module, right?), from the beginning
we've planned to use a secondary battery to supply them, are normal 1.5v AA Batteries in series enough for
those logic parts, or do we have to get a better battery for them as well?

Lastly, we've changed the controllers for the DC Motors. If you take a look at the original thread,the part that we listed each component, you'll notice that the change was from 2x L298N to 1x VNH20SP30 Monster Shield (2 Ch) + 1x VNH20SP30 Monster Motor Module (1 Ch). What are your thoughts about those, are they good enough for what we want? Are they compatible with Arduino UNO running simultaneously?

Thank you for your time, we really appreciate it!

10

KuroG:
• That's it, you gave us a reliable option for the batteries, because here the 18650 (we didn’t find the 16850

My mistake. 18650 indeed.
Get sets with protection electronics built in, then you don't have to worry about overcurrent (when shorted they just shut off) or over discharge.
2,200 mAh means you should be able to draw 2.2A for 1 hour. The batteries themselves can offer several amps of power (I don't know how much exactly). Probably enough to run your rig for 10-30 mins. Good for demos.

About the logic parts (I assume they are the Arduino and Bluetooth Module, right?), from the beginning
we've planned to use a secondary battery to supply them, are normal 1.5v AA Batteries in series enough for
those logic parts, or do we have to get a better battery for them as well?

Maybe another LiPo? The Arduino is happy with that voltage (do make sure to set it to 8 MHz), the Bluetooth probably as well - check specs of your specific module.

VNH20SP30 Monster Shield (2 Ch) + 1x VNH20SP30 Monster Motor Module (1 Ch)

I think you mean the VNH2SP30 Monster Shield?
That should definitely do - but probably overkill. 14A is a LOT of current.
My feeling says that a 2-3A 12V motor will be able to what you need. But that's what you first have to figure out: what kind of torque do you need, then find a motor that fits the specs, then find a motor controller that can control it (for a 2A motor you need a 2-4A controller, not a 14A controller - that's continuous, do check for peak as well).