Larsb review of 72124 motor

EFOIL.builders Propulsion System (Motor, Gears)
68

Could any of you hand rewinders do a video about this? I would love to see how this is done!

69

There’s plenty on youtube. If you search ”rewinding turnigy rotomax” there’s a nice video by a norwegian guy (if i remember it correctly)

1 Like
70

Top one on the forum , bottom mine when I serviced it

71

What do you use to take coating off before soldering ?

72

For multistrand wires i’ve used molten NaOH salt bath, dangerous but effective
For single wire winds dremel :smile:

73

Lackabziehpinzette :hugs:

74

Thanks, i haven’t seen those before :+1:

Otherwise this small bit looks nice:

EDIT: price is 350 EUR… forget it

75

Got the wire today! Now i just need to find some winding time :smile:
image

1 Like
76

Is it class H ? How much ÂşC can it handle ?

77

It’s class H, 200deg C
The varnish on the 2.5x1.25 wire i’ve tried before is incredibly tough so this is high quality wire.

2 Likes
78

Super excited to see the results.
Please do some static tests comparing it to 65 flipsky motor(I do not have one so I can’t compare myself).
If It’s not superior to Flipsky then a general redesign is in order(otherwise it kinda defeats the purpose of making it)

79

You have an idea how you’ll wind it ?

Maybe you can try following :

1 strand in hand (of your rectangular wire of 2mm²)
7 turns
Star connection

Will give around 47% fill factor which should be doable and 6707 RPM unloaded at 55V (122 kV).

Just my calculations.

80

Aiming for 8T delta at 150kV and 50%
I think you have an error, 7T star results in kV 99 (109x11/7/1.73)

Even 6T star at 116kV 38% is an OK winding
5T star at 31% is no improvement, just fixed winding issue.

We’ll see what’s doable for me. This is the first inrunner i do and i probably won’t press out the stator if not absolutely needed

81

You are right. I totally forgot to set the right material for the rotor :rofl: :sweat_smile:

Let me come back in a couple of minutes with something updated.

82

Ok so here it is :sunglasses:

I’m working with a model I designed that I think very close to the reality :

image
image795×926 35.2 KB

(This is 45° of the rotor / stator assembly).

So, based on this model here is what I have :

Current situation :

  • Connection type : Delta
  • Strand diameter : 0,4mm
  • Strands in hand : 7
  • Estimated wire insulation thikness : 0,005 mm
  • Number of turns : 11

Gives me following data :

  • Conductor area : 0,8796 mm²
  • Insulated wire fill factor : 26,48%
  • No-load speed (rpm) : 5411 at 55V => 98kV

These data are in line with what’s been advertised by @Konstantin_Cunichin (minus copper area / wire fill factor). I’ll therefore consider my motor model valid for following optimizations.

Optimized model considering @Larsb 2mm² rectangular wire :

Larsb’s proposal (8T delta) :

  • Connection type : Delta
  • Strand width : 2 mm
  • Strand height : 1 mm
  • Strands in hand : 1
  • Estimated wire insulation thikness : 0,1 mm
  • Number of turns : 8

Gives me following data :

  • Conductor area : 2 mm²
  • Insulated wire fill factor : 55,01%
  • No-load speed (rpm) : 7440 at 55V => 135kV
    => Beware, stator lamination is not optimum for such speeds, efficiency will decrease.

Sliman’s proposal :

  • Connection type : Star
  • Strand width : 2 mm
  • Strand height : 1 mm
  • Strands in hand : 1
  • Estimated wire insulation thikness : 0,1 mm
  • Number of turns : 6

Gives me following data :

  • Conductor area : 2 mm²
  • Insulated wire fill factor : 41,26% (way easier to wind even by machine)
  • No-load speed (rpm) : 5597 at 55V => 102kV

=> around 20% more troque at up to 70% of rotor speed compared to Lars’b proposal

Your turn to choose. In the end it’s a compromise between torque and speed :wink:

4 Likes
83

No, it’s not since i will have a battery and controller that i think can saturate the laminations at both kVs. But i agree on the RPM vs lamination thickness. It doesn’t make sense to run this motor at 7500RPM

Also your motor model is theory while i have measured real kV of this motor so my figure is correct. It’s 109kV.

84

Not sure about this. Konstantin measured the Kv with Vesc tool prior to sending and said they all where 98kV if memory serves. See here :

85

Yes, might be the case but i trust my generator kV measurement more than VESC controller kV since the kV is a motor parameter, when measured in generator mode you get no effect from ESC.

86

Your choice, just wanted to help :wink:

87

Yes, sorry, i appreciate it actually. You only get so far alone so a discussion is always valuable :+1: