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    Brushed to Brushless upgrade
    by billhook301 ๐Ÿ‡ฌ๐Ÿ‡ง ( Leading Seaman)
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    23 Posts 22 Replies 0 Photos 20 Likes
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    DodgyGeezer
    Warrant Officer
    ๐Ÿ“ Brushed to Brushless upgrade
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    Country: ๐Ÿ‡ฌ๐Ÿ‡ง United Kingdom
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    In some respects you can think of a brushless motor as part way between a standard brushed electric motor and an I/C engine.

    The brushless can turn on and off like the electric motor, and is clean like the electric motor.

    It has a high power-to-weight ratio like the I/C engine, can't run slow like the I/C engine, and you need to make sure that the heat is flushed away....
    2
    Martin555
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    Hi DodgyGeezer,
    Thank you, I feel much better informed.

    Martin.
    1
    If it looks right it probably is.
    DodgyGeezer
    Warrant Officer
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    "...I am much wiser about this subject now..."

    Court comment attributed to the famous barrister F E Smith, in the early years of the 20th century:

    "Judge: Smith, I've listened to you for an hour on this case and I'm still not one bit the wiser.
    Smith: None the wiser perhaps, my lord, but certainly better informed."

    ๐Ÿ˜
    1
    Martin555
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    Hi DodgyGeezer,
    Thank you for the information.
    I am much wiser about this subject now.
    Thanks.

    Martin.
    If it looks right it probably is.
    DodgyGeezer
    Warrant Officer
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    "...So would you say that if you made something like my HMS Cottesmore (1/48 scale) and was to run it at more realistic speed it would be better to use brushed motors?..."

    1 - Do what you are happiest with, and experiment to learn more...!

    2 - Brushless are a more efficient motor type, use a more advanced technology, and will probably supersede brushed technology at some point. They are being used more and more often in household appliances. I expect that we will eventually move to them 100%.

    3 - I don't know your particular model, but if you moved to brushless you would get more power and a longer running time out of the same batteries - though maybe not enough to notice...?

    4 - If you want to maintain slow running, you might think about gearing the brushless down, or using a Sensor motor. Both of these options involve extra cost, and you might not find the performance advantage worth while. Sensor prices seem to be coming down, so that might be something to think about for the future. That's probably what I would use if I were making a big slow-speed model at the moment...
    1
    DodgyGeezer
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    ".....brushless motors the main question is speed controller as I would need forward and reverse...."

    Simple answer.

    You can get reversible brushless ESCs. However, watch out, as boats are a minority interest and many cheap reversible brushless ESCs are designed for car use. These may have a 'braking' feature, which means that the controls work like this:

    forward stick = forward
    backward stick = motor braked
    quick forward and backward again = motor goes in reverse

    which is optimum for cars, but cumbersome for boats. A proper boat designed brushless ESC will be fine, as will be a cheap car one where you can turn off the 'brake'. RNinMunich recommends the Quicrun series of Chinese brushless ESCs, but of course products change all the time.

    So check that the ESC you are after is reversible, and has a 'no-brake' setting....


    Rather more complex background explanation.

    This is my understanding of how one particular 'brushless' system works - there may well be other technologies out there... :

    'Commutation' is the process of switching each coil in an electric motor on at the right time to get attracted to the nearest magnet and off when it passes the magnet, so that the armature will rotate in one direction.

    In a brushed motor this happens mechanically, and we don't need to worry about it. If you want to know a bit more, get a Taycol motor and start reading papers like this: http://what-when-how.com/electric-motors/commutation-electri...

    In a brushless motor, commutation is done by software inside the ESC. So the ESC is essential to a brushless motor - it won't run without one.

    What the software in a brushless ESC does is start the motor with a pre-programmed series of activations of coils. Once spinning, the software detects the generated back-emf as a magnet passes each coil, and uses this to work out the motor speed, timing, and hence which coils to activate next, depending on the throttle signal. Obviously, this happens very fast.

    If the motor went round slowly, the generated back-emf would be very low, and the ESC would have difficulty detecting it. So a typical brushless motor has a minimum speed which is quite high compared to a brushed motor.

    In a sensor motor, the ESC can be much more precise about timing because it reads it off the Hall-effect sensor. It can also run at much slower speeds. But the extra kit, and the low production levels mean that these are going to be more expensive motors.

    For a brushless ESC the starting process, and the reversing process, are much more complicated than they are in a brushed motor. In each case the software has to try to detect what the motor is doing and adjust the timing to get it running in the right direction 'blind', with possibly odd feedback from the coil back EMF. For a brushed motor, the ESC just reverses the polarity and the mechanical commutation automatically applies a force in the direction you want.

    The result is that brushless starts can be a bit jerky, and brushless reverses need 'setting up' with a process of signalling from your transmitter or using a program card. Since cheap brushless ESCs are often turned out with little documentation, making them reverse can sometimes be difficult for an inexperienced purchaser.
    http://what-when-how.com/electric-motors/commutation-electric-motors/
    ๐Ÿ”—
    2
    Martin555
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    Hi DodgyGeezer,
    Thank you for all of the information.
    I understand this a little bit more now.
    I see many models hammering across the water but I like to see more scale speeds.
    So would you say that if you made something like my HMS Cottesmore (1/48 scale) and was to run it at more realistic speed it would be better to use brushed motors?
    (I must admit that is what I have fitted)

    Martin.
    If it looks right it probably is.
    billhook301
    Leading Seaman
    ๐Ÿ“ Brushed to Brushless upgrade
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    Thanks for your input DodgyGeezer I mainly fly aircraft and all fitted with brushless motors the main question is speed controller as I would need forward and reverse.
    1
    Sky Diving, if at first you don't succeed, give up.
    RNinMunich
    Fleet Admiral
    ๐Ÿ“ Brushed to Brushless upgrade
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    Country: ๐Ÿ‡ฉ๐Ÿ‡ช Germany
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    "????????????????? "
    Oops! We seem to have ruffled some feathers chaps๐Ÿค”๐Ÿ˜ฎ
    Sorry pardon Bill, but that's what tends to happen with conversations amongst friends!

    A word or two of appreciation for the folks who took time to offer workable solutions (and offer evidence that they work) would not have been out of place.
    Doug
    Young at heart - slightly older in other places ๐Ÿ˜‰ Cheers Doug
    DodgyGeezer
    Warrant Officer
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    Yes - S3 / S4 etc refers to number of cells in a Lipo. Lipos are 3v-4.3v per cell, need special chargers and critical care compared to the more robust NiMh batteries. Unless you really need the small, light, ultra- powerful Lipos for racing or something, I think it's best to stick with hi-power NiMh cells.
    1
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