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-   -   Hacker Motor problem (https://www.wattflyer.com/forums/showthread.php?t=82523)

bigvern 06-08-2022 10:51 AM

Hacker Motor problem
Hi there I have a Hacker A50-16s electric motor in a sebart sukoi , it has at least 15 years old and has done a lot flying
It has always been flown on 6s. Th ecs is a hacker master spin opto 99, overkill I know but it was spare and my hobbyking ecs bit the dust.
The ecs is set to automatic option 2 (outrunner). The ecs was replaced as the hobbyking ecs was making the motor hunt during flight
The hunting has now disappeared however it performs as though the power of the motor is only available at the top 20% of the throttle travel
The motor does run at all the throttle range but it is gutless. The batteries are brand new, the ecs throttle range is calibrated correctly, I have no
strange power curve set as its the same set up I have used for years and has worked before the issues started.
Any ideas ??? My electronics expert buddy is convinced that one of the windings has given up or one of the magnets has lost some of its magnetism

bigvern 06-12-2022 10:36 AM

Well I have done some tested this morning and I have confirmed my thoughts that the motor is not working correctly

At full throttle I am getting 1.23Kw @ 58 amps which is what I was expecting, at 50% throttle I am getting 200w @ 5 amps
not enough to pull the skin off rice pudding as they say !!!
Just checked the price of a replacement Hacker A50-16s, I dont think I will be buying a Hacker :(

ron_van_sommeren 06-12-2022 02:01 PM

Apart from battery voltage, voltage sag, power and current readings you need rpm readings as well for debugging.
At full throttle, half throttle, with and without prop.

Possible causes, problems, solutions
  • Mounting screws too long, delved into motorcoil(s)?
  • No mixers, dual rate, throw reduction active in transmitter?
  • Does a servo on throttle channel do what you expect it to do, i.e. full throw?
  • Battery polarity okay on battery connector? (Something I would always check on a new battery, or a new wiring harnass.)
  • Bad connection somewhere between ESC FETS and/or in motor:
    Motor stuttering? Won't run? Read before asking.
  • Several motor tests
    1. Drytesting brushless motors - WFF (RCG user vollrathd)
    2. Opening an outrunner for visual inspection
    3. Generator test, only using a power drill and a voltmeter
      (Re)winding and building motors - RCG (sticky) → opening post → #40 Generator test.
    4. Overheating magnets causes de-magnetizing (irreversible! :(), which in turn results in higher velocity konstant Kv. Motor wants to run faster, thus drawing more current and more power.
      Motorcurrent and -power drawn are proportional to velocity konstant Kv³ :eek::eek::eek: , resistance losses in the copperwire are proportional to current² :eek::eek:
      Therefore resistance losses are proportional to Kv⁶ :eek::eek::eek::eek::eek::eek:
    5. Higher current → hotter motor → weaker magnets → higher Kv → higher current → hotter motor → weaker magnets → higher Kv → higher current ⟲⟲⟲ etcetera etcetera.
      Thermal runaway, major conflagration :(
    6. Determining whether magnets still have original strength, by determining whether velocity konstant Kv (in rpm/volt) is still the same, three simple straightforward methods.
      www.bavaria-direct.co.za → motor constants
    7. If you don't trust your ESC: use another brushless motor as a generator:
      Three Phase Alternator - Three Phase Motor? - RCG

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