Question UNDERSTANDING AMPERAGE USE FOR 2DOF MOTIONSIM - BEGINNER

This is my first post.

First off, I'm creating a 2DOF MOTION PLATFORM to use with NOLimitsCoaster 2 - Telemetry version. So I've already gathered some electronics components I want to make sure I could start out whit them, and once I had integrated succesfully all the hardware required to make the Platform works out, I'll improve it with better electronic gear.

Well, my first question is about the amperage needed, I've red internet information about it, but I'm still not able to understand it correctly because this information is not focused on MotionSim building, I just dont want to burn my controllers or laptop (the only one I have now) :,(

I have Arduino Uno & Sparkfun Moto Monster Shield. I have two DC motors DME44B-129 24V 0.94 A (Current rating) to test (I definitely cannot move a platform with them but I still couldnt find 12V wiper motors)

@RacingMat says he just added "a punchy 12V Power Supply Unit about 30A" or 47A... isnt this 30A/47A too much current flowing direct to the Sparkfun Motorshield? Can it blow it? Can it blow my Arduino controller?, Can it blow my laptop electronics? How do I avoid an unsafe use of this 30A/47A current? What recommendations could be given? Do I need to use fuses? Does the motoMonsterShield has any way to deal and process this current? How does the current distributes in those electronic components?

If for example I connect this "12V Power Supply Unit 30A" to the MonsterShield connected to my two DC motors DME44B-129 24V 0.94 A, does this 47A current can blow them? bearing in mind those motors work with 0,94A each? Everything via PWM-Arduino.

How many Ampers would be needed for my two small motors (DC motors DME44B-129 24V 0.94 A)? I've already seen them working with the Arduino-Motorshield connection +12.5v/-12.5v but sadly I wasnt given information in the electronics house the amperage they used A last research was that they probably were working with a Power Supply Unit of 12V 2,5A.

hi, if you want to build a motion platform on which you may seat yourself then the motors aren't sufficient enough, too weak at least.

Those motors will be fine for experiments with SimTools and the motor shields to see if you have everything at least talking, but as Pit said, and you noted, not suitable for a sim.

The current listing at .94A on those motors is probably the running current and without load, a 2.5A rated supply should be fine.

You could run those motors on a power supply that can deliver 1000A and while not adviseable, it would work. It's like your house. You can plug in a nightlight and it works even though the outlet can deliver a lot more current. What matters is the voltage being appropriate. If you plug a 12 volt lamp into a 220 volt outlet it blows, right? The voltage has to be appropriate.

You can kind of think about voltage like pressure and current like flow. As long as pressures are appropriate, you will have proper flow as long as your power supply can supply enough flow.

So to answer your questions - you should be able to run the .94A motors from a 30A power supply as long as the voltages are correct. If the MonsterMotos handle 24 volts you are probably good to go. I'm thinking they are 12 volt units though. (Edit - 16 volts max. You need a 12 volt nominal power supply - a 24 volt supply will blow the MMs.) You'll want to make sure. If they are 12 volt rated, then the 30A 24 volt supply could supply the current but the voltage may be too high. Or it could be fine. I'm on a tablet right now and can't check.

Basically you want everything to match on voltage rating and you want to have enough current capability to deliver everything your loads require. Having more current capability is fine and in fact you want some headroom because under load, motors tend to pull lots more current. The caveats are that power supplies that can deliver boatloads of amps can be a bit dangerous so you want to use fuses or circuit breakers (fuses most common) to minimize light shows and sparks if you accidentally short things out.

One last caveat is if you use a power supply that can deliver way more current than you need is that some power supplies need a minimum load to regulate properly. If you aren't in the proper range for the power supply, you may not even see an output and it may appear to not work.

There are lots of good resources on the web that will give you more background on current and voltage.

Actually, in re-reading your post, you noted those motors are 24V, .94A and you want to run with Arduino and MonsterMoto.

Already noted that a 24 volt supply is too much for MonsterMoto. You need a 12V nominal supply. But the motors being rated at 24V means at 12 volts they will probably run but will be very weak on 12V. But they might not even run. Only one way to find out. Hooking them to lower voltage than they are designed for won't hurt motors for just a test. It's too high of a voltage that kills things.

But for hooking things up and experimenting, as long as you get a 12V supply instead of the 24V one, those motors will still probably work just to see if you can can't roll them properly. But they won't have much torque, may not start turning until you hit significant pulse widths, etc.

And last, the chips the MM uses are pretty strong and are designed for high currents. The biggest factor is the heat sinking capability of the circuit board which the MM doesn't have a huge amount of. Lots hang heat sinks off the top of the chip but it's more efficient to cool the board from below. Your call on what you do.

But the chip in the MM is thermally protected and also limits current in case of shorts to around 55A. It's all in the chip datasheet. You can still blow them and the stresses from shorts and little/no cooling can still kill them, but to a first approximation they protect themselves fairly well. Just be careful with them, heat sink and cool them, and use fuses, and you should be ok. Might blow one or more too but lots have.

@Pit Thank you for your answer, those motors are for experimentation only, I still can't find wiper motors.

@Zed thank you for your help, I'm so glad of reading the information you wrote me, I'll actually follow your recommendations to make this system works out.

by the way, yes I've decided using a 12v supply unit, because I want to familiarize whit this tension once I replace the experimentation motors I've gotten to 12v wiper motors of a higher current rating. I've already seen those motors working with MM shield and Arduino to 12v and unknown amperage in the electronic house I purchased them (in another city far from where I live). Just an arduino example though to test if the board and motors worked ok..and they actually did!

Well, I'd like you to help me with this question...What would be a suitable current for the power supply unit in the next diagram, bearing in mind that now I'm adding a cooling fan (DC 12v 1,3A) to the system. Because I need to order the power supply unit online and I just dont want to order one with wrong especifications. I was thinking about six ampers? what do you think? Do I need a math formula to determine a suitable current for a power supply unit? thank you.

It depends. They may want to pull more current than the rating running at a lower voltage even without a load on them because they will probably be running slower than they would at 24 volts. Motors are funny things - they also act like generators and they do it at the same time. That's why starting currents are quite high - the motors aren't turning and so there isn't any generator action going on to oppose the voltage and current that are driving them. As they speed up, they start behaving a bit like generators and that reverse EMF opposes the applied voltage, current through the motor drops, etc. Since you are running them at lower than rated voltage, they will probably be running slow, and because of that won't oppose the applied voltage as much.

On the other hand, with them running at lower voltage, that will tend to reduce the current through the motor. I don't know which effect will win. I think they will pull less current overall but don't know that.

If that is correct than for experimenting, I'd just go with something around 5A to 10A. Those are common and cheap. I just bought an open frame 12 volt 6 amp supply on Amazon for $14. But if your end game is to get wiper motors and you know about what they will pull, I'd just get supplies of that size and not spend the money twice.

As to how much headroom you need over the rated motor current, I don't really have a good feel for that yet. I tend to overdesign rather than cut the margins thin. It costs more but saves on headaches. But I'm new to sizing power supplies for motors in this application and just don't know what to recommend. Motors in motion sims tend to get driven hard and that means more current. Sometimes lots more current. Enough to trigger overcurrent protection in many of the setups people describe here. There is a ton of good information here and the best advice I can give is to slog through all the build threads of people who built a sim like you want to and see what they used, what worked for them and what didn't. And you will pick up lots more information in the process.

Good luck!

Hi @Zed, thank you for the recommendations, I've been working on the prototype & it's getting really good. There is still no Arduino-MM connection but it'll be done during the next few days. I'm thinking to create a new post about the building and connections themselves. I allocated the fan below the MM as you recommended, and powered them with a 12v 5A power supply unit, protected by a 5A car fuse and 5A wires. Its working out pretty well with no issues at all

I have the aluminum heat sinks devices but I dont know if correct to allocate a single one on top of the two VNH2SP30, putting them together, I dont know if it could cause any short-circuit, or it would be better to cut out the heatsink into two pieces and place them everyone on top of each VNH2SP30. I was researching about, but the pictures can not show very well the details.

thank you!!

Hi. I used same heatsink over both chips and it did work well. Just make sure it does not connect to metal legs of any chips.

Apologies, @masterhoo, didn't see this until just now. Yep, as @dr.feelgood says, you should be fine with a single heat sink since the tops of the chips are plastic and don't conduct electricity. His caution is right on, too. The heat sinks shouldn't touch any connections, exposed leads, etc, unless whatever else It touches is a nonconductor.

I'm putting in a seat belt tensioner after some thoughts and conversation with @SeatTime, and am still going bottom-cooled for my JRK that controls that motor. Printed a little box to hold its power supply and power input module with an unused CPU fan for forced air. Grabbed another heat sink - it's a little tall but oh well - and turned it upside down over the fan. The JRK will get clamped with its thermally-conductive foam onto the flat of the heat sink. That way the fan pulls air through the JRK heat sink and blows it down over the power supply heat sinks below. Not all together yet but hopefully it makes sense from the photo.

Thank you @dr.feelgood I'll install the heat sink according with the picture sent. Thank you @Zed, for letting me know those details about the plastic tops of the chips. I'll open a new thread about the setup of the Arduino-MM connection, since I'm currently starting with the wiring process of them. Thank you!!.