Optimizing Motor Performance: Series vs Parallel Wiring

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Discussion Overview

The discussion revolves around the optimal wiring configuration for powering two electric motors (PC case fans) rated at 12V - 0.3 A each, using a power source that outputs 12V at 0.3A. Participants explore the implications of wiring the motors in series versus parallel, particularly in relation to maximizing motor speed and performance.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant suggests that wiring the motors in parallel would maximize voltage across each motor, potentially allowing both to run at full speed.
  • Another participant points out that running both motors at full speed would exceed the power supply's rating, which is limited to 0.3 A.
  • There is a question about whether current or voltage is more critical for motor performance, with some uncertainty expressed regarding the characteristics of motors compared to resistive loads.
  • A participant mentions that wiring in series would likely result in both motors running slower, but this is not definitively established.
  • One participant reports experimental results indicating that neither configuration behaved as theoretically expected, with motors running slower in parallel and unevenly in series.
  • Suggestions are made to consider a higher-rated power supply to accommodate the motors' combined current requirements.

Areas of Agreement / Disagreement

Participants generally agree that the power supply's current rating limits the options for wiring the motors. However, there is no consensus on the exact performance outcomes of the series versus parallel configurations, as experiences and expectations differ.

Contextual Notes

Limitations include the dependence on the specific characteristics of the motors, which may not behave predictably in series or parallel configurations. The discussion also highlights the importance of power supply ratings and the potential for voltage drop under load.

Who May Find This Useful

Individuals interested in electrical engineering, hobbyists working with motors, and those seeking to understand the implications of wiring configurations for performance in practical applications may find this discussion relevant.

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I'm working on a project that needs to power two electric motors (PC case fans). These fans are rated 12V - 0.3 A. The power source is a AC-DC adapter that outputs 12V and rated for 0.3A.

My question is simple: should I wire these motors in series or parallel maximum their speed?

I have a (very) tenuous grasp on electrical engineering. I think that parallel would be better to maximize voltage across the motors but, from what I can gather, this would effectively split the current to each motor while a series circuit would have the same current throughout. Which is more important for an electric motor: current or voltage? Or am I looking at this completely wrong?

Thanks for any help.
 
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Just on the ratings, to run both motors at full speed would exceed the rating of the power supply.
They take 0.3 A each and the supply is rated for 0.3 A.

So, your choice is limited.

You could try putting them in series and accept that they will run slower than normal.

You could run just one of them.

You could find a power supply that can handle 0.6 A.
 
So hooking them up in parallel will allow both fans to run at full speed?

In series, would they both run at half speed?

I can always get a new AC-DC adapter than can handle the increased current if need be.

[Edit] I know its an obvious question, but I'm unsure because they are motors that seem dependent on current, not a load like a simple light.
 
If you put two identical resistors in series each will dissipate one quarter of the power they would have if they were on their own across the same supply.

But motor characteristics are not as predictable as that and they vary with load as well. You would have to try it.

If you can get a better power supply, then try them in parallel to get full power out of them.
 
Ok, that might explain it. I tried both configurations and it seemed that neither one would act as theory suggests (parallel: they would run slower than they did alone; series: one would run faster than the other). I'll look into a higher rated PSU, thanks for the help.
 
Yes, sounds like the power supply voltage was really suffering.

Get a supply with about double what you actually need. Ratings on these are not very conservative and you could easily blow up a supply that is barely good enough.
I'd be looking for 1.5 to 2 amps. Regulated is better even if you have to pay extra.
 

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