upgrading phase wires gone wrong

bwesson

1 µW
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Aug 3, 2021
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hello im new to this forum but certainly not new to electric bikes and i seem to be a little stumped and hoping someone can help shine some light. I have a 1500 watt hub motor and stock it came with very small phase wires like probaby 18 or 20 gauge. its pathetic. I have a kelly controller and i juiced it to the point where my bike goes 53mph and the phase wires got so hot that they melted together and shorted inside the motor where it connects to the coils. No biggy i assumed i need to increase the size anyway given they were so small. I bought 12 gauge wire and there was no chance i was getting all 3 to fit inside the axle. So i settled on getting 2 in the axle and leaving one original phase wire in place but once it exited the axle i spliced in the 3rd 12 gauge wire. Now im having bad vibrations on acceleration and massive loss in torque.... All the phases are soldered and heat shrinked together. I feel okay about the soldering but not great because for some reason i couldnt really get the solder to really melt with the wires that well even with flux...but none the less i feel okay about it. Im wondering if maybe these issues are due to that short section of the phase wire thats really thin? or could it in fact be a bad solder connection? any input would be great. I know this is long and thanks in advance for any help.
 
You need to go really big wires from axle exit to controller, the bigger the wires the better from the axle exit. Othewise you need to find some thin insulation wire to fit inside the axle, I tried ptfe teflon wire and it worked well.
 
A lot of people will strip the insulation off of the wires where they enter the axle and shrink wrap them instead. This usually gives enough clearance to get all of them through.

As for the issues you're now experiencing, hard to say. Could be a poor connection, or you could conceivably have damaged the controller or motor during the initial meltdown. Further exploration will be necessary to determine what the issue is.
 
You could look into motor winding wire, not sure if anyone has done that and then heat shrink the wire where it goes through the axle but I havent read anyone doing that and its maybe because its just to easy to nick the coating on the wire.

Found this but smallest is 16 awg
https://www.alphawire.com/Products/wire/hook-up-wire/ThermoThin/2616
a) Conductor 16 (19/.0117) AWG 10% Nickel Plated Copper 0.056
b) Insulation 0.007" Wall, Nom. PFA 0.070+/- 0.002

A better explaination, 16g is the smallest, 3x16g=11g (effective)
https://www.digikey.com/en/product-highlight/a/alpha-wire/thermothin-hook-up-wire
ThermoThin's ECA fluoropolymer insulation contributes to the cable's smaller size while providing excellent dielectric properties, as well as outstanding chemical resistance. This 600 V wire is available in conductor sizes from 36 AWG to 16 AWG and is well suited for a multitude of applications where space is at a premium and extreme temperatures must be withstood.

More info
https://huesonwire.com/site/capabilities/reduced-diameter-cables/

20g is the smallest
https://wire-cable-tubing.wireandcable.com/viewitems/mil-w-16878-nema-hp3-hp4-mil-aero-wire/-6-type-et-wire-thin-wall-extruded-ptfe-insulation

Types Explained
https://blog.jemelectronics.com/wire-insulation-types-explained

12g thin insulation
https://www.wirestrander.com/portfolio/items/thin-insulation-automotive-wire-extrusion-line

Magnet wire
https://temcoindustrial.com/product-guides/wire-cable-and-accessories/magnet-wire/magnet-wire-faq
If you use heat shrink you can install the phase wires, then shove heat shrink from the outside into the axle, do each phase then heat shrink all 3.

Another way is to use a Sensorless Controller so all you need is 3 phase wires and no hall sensor wires. If you want a motor temp sensor then you do that wire first. Buy a bunch of incremental wire gauge in the best insulation thickness you can find and try to fit 3x10g to start, and move thinner. Then do as I said, install 10g or larger wire from axle exit to the controller.

Some people just use stock phase wires and install 10g from axle exit to controller.

Or you can buy a motor with better wire routing measures.
https://ebikes.ca/shop/electric-bicycle-parts/motors/igh-305.html
https://ebikes.ca/shop/electric-bicycle-parts/motors/grin-all-axle-hub-fast-wind.html
 
HrKlev said:
So, you have now 2 large phase wires and one thin? Idk much about motor theory, but that doesnt sound like a good setup. The thin phase wire will suffer a much higher voltage loss than the two others.

I have 2 large and 1 thin only until it exits the axle and then it goes to large
 
bwesson said:
HrKlev said:
So, you have now 2 large phase wires and one thin? Idk much about motor theory, but that doesnt sound like a good setup. The thin phase wire will suffer a much higher voltage loss than the two others.

I have 2 large and 1 thin only until it exits the axle and then it goes to large
That short bit of "thin" wire will act as "resistor" and be where the heat build up is.
I think that the HiGo L1019 cables have some of the smallest compound cables you can get.
The OD is 7.5 to 7.7mm (measured) with the exterior jacket. That jacket is about 0.8mm ... so a bit less w/o the jacket.
Can you fit that through you axle?
View attachment HiGo L1019 Connectors and Cables.pdf
 
LewTwo said:
bwesson said:
HrKlev said:
So, you have now 2 large phase wires and one thin? Idk much about motor theory, but that doesnt sound like a good setup. The thin phase wire will suffer a much higher voltage loss than the two others.

I have 2 large and 1 thin only until it exits the axle and then it goes to large
That short bit of "thin" wire will act as "resistor" and be where the heat build up is.
I think that the HiGo L1019 cables have some of the smallest compound cables you can get.
The OD is 7.5 to 7.7mm (measured) with the exterior jacket. That jacket is about 0.8mm ... so a bit less w/o the jacket.
Can you fit that through you axle?
HiGo L1019 Connectors and Cables.pdf

No I doubt it. The current wire is 4.5mm OD
 
I was in a rush in my last post so I didnt really have a good look around.

https://www.daburn.com/CRTHighVoltageCoronaResistantPTFEWire.aspx
Chart gives you OD, and says
Small Size: You do not need bulky, thick insulation jacketing as used with silicone rubber and polyethylene insulation to get your Hi-Voltage requirements.
No short lengths, 250m is a ton.
12g OD ia 0.142
10g OD is 0.174
A bit shorter OD here
https://www.daburn.com/2428PTFEWireMIL-W-16878Type-EEMIL-W-16878/5.aspx

I found a guy who sold whatever length you wanted in PTFE Teflon, he was a guy selling guitar stuff but he had the ptfe wire I used and out of California. He wasnt on ebay, but theres always someone selling shorter lengths/quantities somewhere, like I found a guy on ebay selling ziplock bags of Mobil 28 aviation grease I used for geared motor. Minumum quantity on that from auth dealer was like a case @ $200+
 
speedmd said:
Is it running higher RPMs also or just lower torque? Sounds to me like a bad connection as mentioned above. Digital non contact thermometer will spot it if so. Should show higher resistance on a multimeter also.

It's vibrating and sluggish on lower torque. Once I get up to speed it smooths out and rides like normal
 
Grin sells a nice 9mm 3x12awg + 7x24awg cable.. Also use teflon coated high voltage wire, not the silicone thick jacket stuff. I use 10 gauge AWM wire. rated 1000 volts 600 degree C
 
Thinnest insulation can be easily done with kapton tape. But be sure it is real kapton, there are lot of fakes around, try it with soldering iron first, if it melts it is fake. Firs strip PVC insulation of a standard stranded cable. Wind a layer of 1cm wide kapton tape so it overlaps half or two thirds of previous turn. Finish it with another layer but this time not wound around, but align wider strip of tape along the wire and roll it in. This is to protect the wound tape from damage on edges - it will pass through freely. I advice to get rid of any sharp edges on the axle first and then cover it with a layer of kapton tape.
Kapton tape is very thin, can withstand temperatures up to 300°C short term and is quite resistant to abrasion. This is much thinner and way much heat resistant solution. You can even better fit the cable if the strands in it are not twisted, after covering them with kapton tape the strands are still able to change shape of the cross section and filling square slot can be much efficient this way - you can get rid of the empty spaces that round cables allways leave...
Example from my experience - I was able to fit 3x6mm2 in place of 3x1,5mm2 in Magic Pie motor... It works without problems third season I think now...
 
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