Questions about hall installation after a rewind

Electric Motors and Controllers
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John in CR   100 GW

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Questions about hall installation after a rewind

Post by John in CR » Feb 08 2020 9:30pm

I'm bringing a stator to be rewound on Monday, and I plan to terminate them and install halls myself. The factory installed the halls at 120° intervals between gaps in the stator teeth, which I plan to copy. It doesn't matter which tooth I use as a starting point does it?

I don't understand the purpose of hall circuit boards. From the factory these motors don't have them, and the hall wires just go straight to the axle where the gnd and +5v of the three are combined to go through the axle. Is there any potential advantage of robbing a hall circuit board from a dead motor to install on this one?

I know to take care that all 3 hall sensors are mounted facing the same direction, and I'll copy the depth the factory used, since they attained 93% peak efficiency. That high efficiency was despite the extra resistance losses of the ingenious 2 speed (series/parallel) manual switching mechanism where they separated the copper strands into 2 groups for each phase, and achieved the switching with a set of 2 position rings with spring loaded contacts and a shaft to through the axle on the non-wire side. I'm doing away with the switching which was the failure prone point of the motor.

Since the rewind will almost double the Kv, I can make use of the hole for the shifting shaft to bring one of the thicker phase wires required outside of the motor. I'm lucky that hole exists, so I don't have to make a new axle and use larger bearings with greater parasitic losses, so I hope to increase efficiency a bit with this rework as well as more than double its power handling at 78V. With the 2 speed contacts soldered in high position retaining the relatively long and thin transitions copper in the switching mech, and poor ventilation these have been run without issue at over 12kw, so with better ventilation and a higher Kv I think it should handle whatever a Thermo Nucular 24fet controller can throw at it. 8)


John in CR   100 GW

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Re: Questions about hall installation after a rewind

Post by John in CR » Feb 16 2020 8:20pm

Thanks Larsb, but I'm not sure the one with the video proved one way was correct, since it sounded enough faster that the increase in no-load current would be completely explained by the increase in rpm. I'd really need to hear the startup and low rpm with both to know for sure, but the second set motor sounded slightly better to me.

If the maximum I can be off is one slot, and my Nucular controller can't self adjust to the correct perfect timing, then I think I'll install 2 sets of halls, so I can see which is best under load as well.

I completely mangled a wiring harness on a HubMonster one time, and after installing new phase and hall wires it was impossible to tell which went to which. I ran it a couple of weeks with the halls crossed (one slot difference), and there was a bit more sound from the motor on launch, and not quite as much torque, with a bit higher no-load rpm. Plus the motor ran noticeably warmer. Still, I was able to hit 166kph with the halls crossed, and only managed 172kph with the halls the right way and with a bit fresher charge.

larsb   1 MW

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Re: Questions about hall installation after a rewind

Post by larsb » Feb 17 2020 12:21am

You’re correct, burties test only proves there’s a difference between the slots.

surely the nuc has phase angle shift setting? Then it won’t matter, you can set whatever shift that’s optimal
Ride on!

John in CR   100 GW

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Re: Questions about hall installation after a rewind

Post by John in CR » Feb 17 2020 1:19pm

larsb wrote:
Feb 17 2020 12:21am
You’re correct, burties test only proves there’s a difference between the slots.

surely the nuc has phase angle shift setting? Then it won’t matter, you can set whatever shift that’s optimal
Hopefully it does it during the auto motor setup routine that also figures out hall corrections too.

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Re: Questions about hall installation after a rewind

Post by larsb » Feb 17 2020 3:16pm

Possibly but i guess there’s a setting also. All good controllers has it.
Ride on!

John in CR   100 GW

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Re: Questions about hall installation after a rewind

Post by John in CR » Feb 18 2020 12:57am

larsb wrote:
Feb 17 2020 3:16pm
Possibly but i guess there’s a setting also. All good controllers has it.
I'm sure it does. I haven't even begun to scratch the surface of the options available. Since the actual timing difference is quite small, the degrees in 1 slot width - the degrees in 1 magnet width, I'm confident the controller will determine the ideal adjustments for low speed torque as well as higher rpm operation. During auto setup of the controller spins the motor up 5 times, once each for determining throttle and brake voltages, and then 3 more times at different rpm for fine tuning timing.

In an abundance of caution I'm going to run dual sets of halls anyway, so I can try both ways and see if there's any difference.

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Re: Questions about hall installation after a rewind

Post by larsb » Feb 18 2020 6:21am

that'll be interesting. If you do then please post the results in some thread :thumb:
Ride on!

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TommyCat   1 kW

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Re: Questions about hall installation after a rewind

Post by TommyCat » Feb 18 2020 9:20am

Just wondering if you'd seen this or if it would help...

http://mitrocketscience.blogspot.com/20 ... t-for.html
See my completed Magic Pie V5 rear hub E-Bike build Here!

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