Fitting wire in a motor:

[Mathurin]

I'd like to do this only once, do it right...

It would appear the biggest I can fit into my motor's axle is AWG16. So be it.
It's bigger then the stock cable was anyways. The hall sensor wires were
made to fit by squeezing them into the gaps between the cables, I plan to
cover this mess with heat shrink tube and then pull it into the axle as far as
it'll go, so it should look like one cable from the motor onto the
connectors. Good plan?

How should I connect these cables to the motor coils?
I'm thinking lead-free solder and a peice of heat shrink tubing.

What I see is that the original wire is twisted/soldered into a buncha coil
wires that apparently got the insulation scratched off of 'em, and this is
covered with a cylindrical cloth insulator that's covered with transparent
plastic. I could prolly the new cable fit into this original insulator.

 

[fechter]

Twist, solder, and heatshrink should be good.
You want to avoid stresses on the wires (leave a little slack) and also prevent them from vibrating enough to crack off later. The cloth insulation stuff doesn't melt when it gets hot. Heatshrink can, so avoid having the heatshrink pressed against another wire it could melt through.
I use silicone glue to tack the wires down. Nylon zip ties come in handy sometimes too.

16ga is pretty small, but if the length of it is short, the losses can be minimized. It would be best if there was just enough 16ga to get through the tight spot, then switch to a heavier gauge for the rest of the wiring.

 

[D-Man]

Mathurin, did you do this mod yet?

 

[Mathurin]

Not completed yet, all my ebike stuff is collecting dust at the moment,
been waiting on the fets to get here. I'll post pics when it happens.

Been thinking though:
How about I strip some 14AWG and put some shrink tube on it instead?
That just may be thin enoufgh to fit in the axle...

 

[D-Man]

I've seen shrink sleeving shrink right off the wire when it gets hot.

 

[fechter]

You could use Teflon shrink tubing that doesn't melt very easy.
As far as the solder connections, if one wire if fat enough, it should carry away the heat enough to prevent melting. If it's really going to get hot, you can use silver solder that melts at a much higher temperature. Crimping is another option. That's what they use to attach the heater wires in a hair dryer. You can remove the plastic shell from crimp connectors and insulate them with something that doesn't melt (like fiberglass tape).

 

[Mathurin]

OK, I keep ruining the wires. I can fit'em in using lots of lube, but they keep stripping the insulation at the bend when being pulled/pushed through. Maybe I'll whip out the angle grinder to make the bend less sharp.


3 AWG16, the five small strands are distributed between the openings:

Just barely fits at all

Trouble at the other end

Edit:

Angle grinder for the most part and finished with the dremel. Hella sloppy
workmanship because I couldn't find my glasses - so I had to grind with
my eyes closed, stop grinding, look, close eyes, grind some more...

EditII: Success!

Here's what you do: Start by fitting the phat cables in 1st, make shure they're all at the right length and there's a hole on the outer bend side cause that's where the hall cables are gonna go. If it's tight, you can push/pull them back and forward to get the third one through. The hall wires are very thin & bendy, so you can't put them on top easily. Slip one at a time in so it touches the outer bend part, and it ought to come out the other end. The last ones are hard to fit, but you can pull the 3-4 hall wires already in without damaging them, then adjust the lengths once they've peeped through. Don't try & pull the coil cables back & forth at this stage, it's be real hard and you'll strip the insulation off at the bend.

 

[D-Man]

I say good show! Those 3 wires look pretty big. You say they are 16 gauge?

 

[Mathurin]

Yup, there's no way I could fit 14 in there. Maybe making the hole bigger/smoother or maybe cable with better quality (thinner) insulation?

But these are a good bit bigger then the originals anyways.

 

[Mathurin]

OK, how about two 14 (or 12?) and using the bike frame/axle as third cable?

 

[Lessss]

I can see it now, he goes to tighten a bolt forgetting the bike is on. He touches the bolt and the ground with his other hand and 48V later. ahzazahaahzaaahaza.

 

[fechter]

OK, how about two 14 (or 12?) and using the bike frame/axle as third cable?

It's "bad practice" to use the frame as a conductor for anything other than maybe 12v lighting. I don't even recommend that unless it's from an isolated dc-dc converter. With an energized frame, the likelyhood of a single failure causing an "unpleasant thermal event" (bike fire) is greatly increased.
With proper fusing, it can be done safely, but I wouldn't do it.

 

[knoxie]

Good work

But what power do you want to run through the cable? as if you keep the wires really short you can get away with thinner cable. I can push 40A through 1.2mm cable with no problems as long as its not longer than about 6 inches. There are loads of online calculators that you can use to test this theory.

Nice job on packing the cables in as the thicker the better, but you may have been able to use the original cable as long as you clipped it right back? the other option is of course to limit the current and up the voltage to get the same power, which means you can keep the existing wire.

Cheers

Knoxie

 

[Mathurin]

Check out the first picture in failed component pics:
http://endless-sphere.com/forums/viewtopic.php?t=155

Serious, I wanna pass about as much current as possible.
And yeah, I do plan to clip it about as short as practical to minimise loss.

Though for now I'm eyeballing weight reduction...

 

[Mathurin]

Right, so once you've passed the wire and all, remember to pass bearings, face plates, nuts etc. before installing the connectors, otherwise they probably won't fit through.