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ALDI stick vac conversion to brushless

Discussion in 'Electronics & Electrics' started by Kimmoth, Sep 15, 2023.

  1. Kimmoth

    Kimmoth Member

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    Bought one of these knowing I wouldn't get much for a hundred bucks, but it seems to have decent enough bones. Figured I'd probably have a go at... overclocking it ;)

    Having known of the existence of aftermarket RC motors since the 80s, and how much difference they make (and that was before brushless!), I've had the idea to hot up a cordless gizmo with such a motor for ages, since I realised many of them use the same size motor. So anyway, it's time.

    This thing is 6s, 2.2Ah, with a 120W 545 motor, which was specced with advanced timing (there are three adjacent notches in the end of the can to hold the end cap in different places). Not sure what rpm it runs at, but it's good for about twenty minutes at full power. I figure a more efficient brushless motor running at like 250-300W might give it some proper grunt if there isn't too much flow restriction.

    The plan is to use my 3p5s/15s DeWalt FlexVolt batteries with it, which are 6Ah/2Ah. I'm assuming it makes a lot more sense to use them in 5s rather than 15s, but correct me if I'm mistaken... Anyway, I'm hoping for at least about half an hour from these batteries.

    Can anyone tell me the disadvantage of sensorless motors? A vac would seem like a fairly undemanding application; I'm guessing I can totally get away with the cheaper option, right?

    For the controller, I found this: https://www.ebay.com.au/itm/295865099072
    Seems hard to go wrong for $20. This would be suitable, right?

    As for motors, it seems a 3650 is the go. I get winding specs but not kV, not sure what that's about. Can't be actual kilovolts, can it? There's no way the tiny SMD board in my little drone is handling 11,000V with those tiny spark gaps...? I found this page about speccing a brushless motor, but couldn't make enough sense from it. As for number of poles, I'm guessing I don't have to worry about that since the cheapo motors I'm looking at don't seem to offer different options.

    Then I just grab a DeWalt battery clip and get hacking. Hoping I can get enough knowledgeable peeps to chime in to help me figure out the spec I need for motor and controller...

    For under $65 plus BYO tool batteries, this project seems pretty worthwhile, and probably quite applicable to similar gadgets. When the bits arrive I'll post a step-by-step for posterity.
     
  2. /invariance\

    /invariance\ Member

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    This sounds like fun.
    A bit Tim "The Toolman" Taylor-ish ;)
     
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  3. ArmoureD

    ArmoureD Member

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    Sounds like one hell of a mission for a stick vacc but it'll be fun none the less.

    Back in my younger years my friend installed $5k worth of audio gear in a $1.5k car. Silly move but he achieved his task.
     
  4. chook

    chook Member

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    Sounds like he was meant to be a PC enthusiast and spend thousands cooling his Celeron 300A so that he could save a few hundred on the CPU itself ;).
     
  5. mAJORD

    mAJORD Member

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    KV rating is a term generally used for RC cars, planes etc , it's RPM per Volt un loaded. It's not going to matter too much I don't think, because even the lower end of these motors will spin faster than the old 545 brushed motor most likely volt for volt.

    the ESC you looking at seems a bit weedy , you might be better off with something resembling a bit more of an RC ESC, just with manual speed control. or an actual EC ESC thats designed to work with that motor, then some form of PWM to controll it


    PS I had this exact vac (if it's the one they put on sale recently) , that it was pretty good for the $, but it was the battery that died on it in the end, and quite prematurly, so replacing them is good.. other than that it was fine. Just clean the rotating brush of hair often if you have long haired ppl in your house, they don't like that at all, and will mess up the bearing in there.

    i replaced it with the Viaomi A9, which is better, but it's also another $100
     
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  6. Thraxeh

    Thraxeh Member

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    Not if you have seen Great Scott!'s Youtube channel - he wanted to do something similar but with a different kind of vacuum and mainly focused on the 3D printing of a different turbine, but he is using the same kind of motors and ESC's you are probably wanting to implement, so might be worth a watch still...

     
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  7. OP
    OP
    Kimmoth

    Kimmoth Member

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    [​IMG]

    I was thinking let’s see how that $20 controller goes, but I had to pay another $10 to avoid a long shipping delay, so I had a look what there was for $30. This one comes with a direction switch.

    It occurred to me yesterday while banging dust out of the filter, being able to chuck it in reverse could be a good thing. I assume a centrifugal impeller isn’t completely useless in reverse…?
     
  8. pH@tTm@N

    pH@tTm@N Member

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    interesting project, I like it.
    Just 1 thing to watch out for probably covered in the youtube vid. The impeller will only be efficient at a certain range of RPM. Hopefully in your case it has a bunch of RPM remaining, but at some point more RPM will just = more noise, and possibly LESS suction. In addition there will be a point where more RPM will mean the impeller just lets go :) So more not always = better
     
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  9. OP
    OP
    Kimmoth

    Kimmoth Member

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    Yeah, I'm going to come up with some sort of rig to pull water up a tube, to get a proper quantitative comparison.

    If it... doesn't suck, maybe I can find a higher rpm impeller to fit. There appears to be a lot of similar parts available.

    Or! Maybe it's possible to just tweak the free ends of the vanes to sufficiently alter the impeller's characteristics.
     
    Last edited: Sep 22, 2023
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  10. OP
    OP
    Kimmoth

    Kimmoth Member

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    Here's the baseline. Ghetto vacuum gauge goes up to about 2.7m.

    [​IMG]

    Tried reversing the polarity, but there's a hint in the name... centrifugal impeller still centrifugally impels, only poorly.
     
    Last edited: Sep 22, 2023
  11. OP
    OP
    Kimmoth

    Kimmoth Member

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    Got the controller and battery clip, but Australia Post is incapable of performing a click and collect delivery and has consigned the motor to limbo... maybe I'll get hold of it today, fingers crossed
     
  12. OP
    OP
    Kimmoth

    Kimmoth Member

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    So the controller could only handle half the amps the motor needed, and fried in about a second.

    Ordered one of these in 50A, that should do the trick. Gotta hook it up to an Arduino though, so that's a bit of extra hassle... Hope I can find my stash of nanos
     
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  13. Current

    Current Member

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    What about a relay. Apply 12v to one side, the other side fires through 100amps or less ( 100 amp rated relay)

    That way you'll truly find out what she can do.
     
  14. mtma

    mtma Member

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    Sensorless controllers generally have lower ability at start up. If the motor is loaded with resistance torque it may not start up correctly or might be unstable at low speeds when loaded.

    The sensorless controller/motor combination uses information from the back-emf to derive the commutation timing, which usually means that the motor has to be spinning in order for the timing information to be detected. For a fan application this is usually irrelevant, in fact some sensored controllers transition to sensorless at a certain speed because the back-emf actually contains more accurate information than the electromechanical setup of the sensors, so there would be no difference a the operating point.

    As an aside, there's actually methods to detect the rotor position that don't necessarily need the motor to be spinning but don't expect many hobby grade ESC's to implement anything useful there unless they're for traction, but again for a fan it's basically irrelevant.
     
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  15. OP
    OP
    Kimmoth

    Kimmoth Member

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    A relay would only work for a brushed motor.
     
  16. OP
    OP
    Kimmoth

    Kimmoth Member

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    So removing the impeller was pretty fraught; only just possible without destroying it. But unfortunately I was too conservative with the kv spec on the brushless motor, and it doesn't pull as hard as the original. Also the original electronics cut out after a few seconds without the suction motor attached, which makes the power head not a thing... That at least is easily rectified by grinding all the circuitry off the board soldered to the original battery and replacing it with a $10 BMS.

    I shelved it when I found an unused DeWalt stick vac for cheap while looking for replacement impellers, but that thing is actually pretty gutless and has no power head... So I guess at some point I'll buy a faster motor and see if I can remove the impeller again... Should've actually gone ahead and insisted when I tried and failed to get the back off the brushless motor for a squiz, because now I have to do it with the thing screwed onto the impeller assembly... Give myself a 50/50 chance for that, and if I fail, it's junk unless I scrounge an impeller from a similar vac.

    Had a look inside the DeWalt; it actually uses a larger motor with a 5mm shaft and a larger diameter impeller, which seems more readily replaceable, except for the fact I can only find them with an 8mm hole which is just through thin sheet; I'd have to get onto a lathe to make an adaptor, bugger that. Also doubtful there's an aftermarket scene for that size motor, though I haven't checked.
     
  17. OP
    OP
    Kimmoth

    Kimmoth Member

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    What I should've done, and would have, if I'd come across the info that a brushed motor is at little disadvantage in a fixed rpm application like this, is to see how it went on 5s before going brushless, but I guess I only realised the suction was already pretty decent after I tried the DeWalt on my vacuum gauge.
     
  18. Mickatroid

    Mickatroid Member

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    Many years ago I had a mains powered ozito blower from Bunnings. I had never had a blower before and was stunned by its air output. A couple of years later it had a safety recall because the impellers were exploding. The replacement was so gutless.

    Two things there. If they explode it can harm you but that impeller at least could handle a lot more RPM so far as throughput went, even if it did explode sometimes :leet:
     

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