Brushless pump motor

Discussion in 'Electrical & Radio' started by ZARUBA1987, Sep 29, 2020.

  1. ZARUBA1987

    ZARUBA1987 Well-Known Member

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    Just curious. Question for the captains that run brushless motors on there pumps. What Are key feature to look for ? I may plan to run my full unit pump brushless info would be appreciated
     
  2. SnipeHunter

    SnipeHunter Well-Known Member

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    Shaft Size should be the same as your impeller shaft (1/8" and 3mm are pretty much interchangeable. On the other hand if the motor shaft is 4 or 5mm and the impeller has a 1/8" hole.....that no work-y.

    KV - aka how fast do you want it to turn (KV * Battery Voltage = RPM)

    Motor voltage rating - often expressed as a range like 2-4S LiPoly( which basically means 7.4-14.8V) The motor will most likely run outside of that range, you just might run into some problems.

    A suitable ESC to control/run it, you can't just use a relay like with brushed motors.

    Bolt Pattern to attach it to the pump, depends on the pump and how easy/hard it is to drill a few new holes for you.

    On an Outrunner motor the outer body spins along with the shaft so you want to keep stuff away from that, an Inrunner is more like typical hobby motor with the can is stationary and just the shaft spin. THis is less of a big deal than it sounds like but something to be aware about.
     
    Nate G and Beaver like this.
  3. rcengr

    rcengr Vendor

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    I also replace the bearings with oilite bearings. I find the tiny ball bearings don't last very long once they get wet.

    I usually put a shroud around the motor. This not only protects the pump from things that may rub, it reduces swirl which drops amp draw and reduces air ingestion.
     
  4. Kevin P.

    Kevin P. Well-Known Member

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    For outrunners, the NTM propdrive 28mm series has been popular.

    Here's a summary of my experience:
    For 4S LiFe / 3S LiPo, around 1800kV gives an optimal balance between flowrate and current draw (25A) with the BC pump. If your attitude is "Give me all she's got captain!" then around 2200kV approaches the high end, but you pay a fair amount of amps (+10-15) for fractions of a gpm. As Chris mentioned, RPM is directly proportional to voltage, so if you're running 2S, then you'd want a higher kV (2700 - 3000ish) but your current draw would be beyond what I'd recommend (P = I * V).

    I printed pump shield for the reasons mentioned above, I made it snap on to the BC pump base and use two posts for anchoring/quick screen cleaning. Has worked out great so far. Sort of see it here, I added some screen around it to keep out hoses/wires
    https://rcwarshipcombat.com/threads/wwi-kongo-ircwcc.446322/page-11#post-533725

    Specific motors:

    Need the 19mm bolt spacing pump motor plate from BC

    The shaft on this one is a little short for the BC pump, but it's worked OK during my testing
    https://hobbyking.com/en_us/propdri...148&indexName=hbk_live_magento_en_us_products

    I picked up 2350kV turnigy motors with a 4mm shaft, so need a different impeller from BC, but I feel more confident in the impeller/shaft engagement. Looks like they aren't listed on hobbyking anymore

    For an ESC, I've been using about 60A car ESCs from HK. I like this one because of heat sink it comes with
    https://hobbyking.com/en_us/hobbyki...606&indexName=hbk_live_magento_en_us_products

    I have files for potting forms too. So far so good with my operational experience. I've seen a fair amount of pump ESCs smoke in the past, so have extras
     
    Last edited: Sep 30, 2020
  5. ZARUBA1987

    ZARUBA1987 Well-Known Member

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    Location:
    Tarkington Tx
    Alway appreciate your technical write up kevin. You always get me pointed in the right direction. I’m running 3s. That video of your Kongo turned fire hose was crazy
     
    Last edited: Oct 1, 2020