Burning phase wire contacts that breakdown

medusa569

medusa569

100 W
Joined
Sep 17, 2010
Messages
161
Location
Washington DC
It happens occasionally but I never know when. I run a 42 volt battery on a 9C motor.
The motor wire look to be about 14 gauge...and I currently switched from bullets ( which also burned and eventually melted) to a spade type that allegedly was rated for higher temps. How is it people using higher voltage battery packs aren't complaining about wire /contact melt down and yet I'm getting it. Do i need a thicker wire in the motor, change to a higher temp type wire or use acid based solder? HELP.
 
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I had heat issue with my phase wires too. I had them all jammed in my downtube and bullet connectors.

What I did was, shorten the phase wires as much as I can. I also got rid of the bullet connectors and installed an MT60 connector. It’s rated for ~100 amps. Shortening the wires about 6-8 inches and this connector seem to resolve the issue, for me. By shortening the wires, they lay nice and straight. When I stripped them back, to shorten them, I noticed some insulation starting to melt at the hard bends in the wire.
 
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How many battery amps are you running on the thing?

If we're talking >40A, you could benefit very much from:
As short of phase wires as you can get away with..
And/or an upgrade to 12 gauge wire.. by cutting the wires about 1-2 inches out of the axle and then soldering 12ga on.. ( i would suggest two layers of shrink tube at the least to protect the wires after )
 
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I don't know how many amps I'm dealing with ...I'll report that back later on. I followed one of the Mikah videos when i built my last pack. The current connectors I\m using are spades allegedly rated for 10-12 gauge wire and temps of 900 degrees F. They really do get hot. I've though about increasing the phase wirtes but it's a tight fit for the anxel exit as it is. Can i safely increase the hole for the thicker wires? I will say that i left bukllet type connectors behinf about a year or so ago as they did charge and burn away. This time it seems that the solder is the melting point but i'll have to recheck what happened on my last ride. I never knew that soldering the phases was being done. even if you soldered it how is the heat dissipated? The wires out of the motor around already about 6".
 
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medusa569 said:
It happens occasionally but I never know when. I run a 42 volt battery on a 9C motor.
The motor wire look to be about 14 gauge...and I currently switched from bullets ( which also burned and eventually melted) to a spade type that allegedly was rated for higher temps. How is it people using higher voltage battery packs aren't complaining about wire /contact melt down and yet I'm getting it. Do i need a thicker wire in the motor, change to a higher temp type wire or use acid based solder? HELP.
Click to expand...
Switching to good quality connectors will probably solve your issue. The wires are probably just getting hot because they are conducting heat away from the crappy connectors (if the connector is heating up, it's be definition crappy). Are you crimping or soldering them.? Similar to how some people will increase the conductor size up to the motor, copper is really efficient at conducting heat, so the thicker conductors will pull the heat away from the thinner ones exiting the motor. Connectors should never heat up if they are sized properly and the bond between the wires and connector is solid.
 
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medusa569 said:
I don't know how many amps I'm dealing with ...I'll report that back later on. I followed one of the Mikah videos when i built my last pack. The current connectors I\m using are spades allegedly rated for 10-12 gauge wire and temps of 900 degrees F. They really do get hot. I've though about increasing the phase wirtes but it's a tight fit for the anxel exit as it is. Can i safely increase the hole for the thicker wires? I will say that i left bukllet type connectors behinf about a year or so ago as they did charge and burn away. This time it seems that the solder is the melting point but i'll have to recheck what happened on my last ride. I never knew that soldering the phases was being done. edven if you soldered it how is the heat dissipated? THe wires out of the motor around already about 6".
Click to expand...

I wouldn't worry about expanding the axle, upgraded wires 1 inch out of the axle is totally fine. Think about it, you're lowering resistance in ~90% of the wiring, the last 10% of the wiring ( from axle entrance to motor ) matters a lot less.

If your current wires get hot then a fatter guage wire is 100% recommended. Once you remove that resistance, you will notice an increase in available power since the power that was previously used to heat the wires is now making it into the motor ;)

Like other people said i would consider soldering on some seriously beefy aftermarket connectors also, i like 4mm hobbyking bullet connectors but they're a pain in the ass to solder so i wouldn't vouch for them today. :)
 
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scianiac said:
What connectors are you using exactly? Picture or link? It sounds like they are just poor quality connectors of both types. Even half decent quality bullet connectors in the 6-10mm range can handle 100s of amps.
Click to expand...
I'm currently using XT150 connectors. I like them the best so far. They require a good amount of heat to solder them on though.

PS. Never use acid core solder for electronics.
 
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Ah I should have been more specific there, I meant what connectors is OP using as I have a suspicion they are those cheap crimp on barrel or spade connectors you get in big sets that aren't worth the metal they're made from.

But yes I totally agree the XT series is my favorite connectors so far, slowing converting everything to XT30/XT60/XT150 but am trying some QS8s and 8mm bullets for phase on my new build, overkill but kinda just wanted to try them out. Soldering the XT150, the most important trick is to plug another connector in when you solder the controller side which keeps the pins aligned even if you overheat the nylon shell with an underpowered iron.
 
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I’m not the best at soldering. Flux and tinned the wire before solder. I was just sure to have the conductor pushed all the way into the connector and enough solder to secure the wire. I didn’t want to make a mess. It was a bit tricky. Just be sure that the wires are all the exact same length and to slip the ends over the wires BEFORE soldering.
 
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Thanks to all who responded. Luckily this time only one wire's solder melted. Just soldered it back in but did notice how thin those phase wires are coming from the motor. I think I will switch them out for thicker wires. I am glad though to see that the simple spade connectors ( rated 100 amps) i currently have did not suffer any burning. So I think i'll beef up the wires and choose a solder rated for higher temps. While the xt150 looks convenient (but expensive) as it was pointed out you can't easily test with them. For the hall wires what is the thinnest I can get away with? If I'm going to open the motor i might as well solder them back in. I won't trim them back yet and I noticed the wire length on ebikes.ca are pretty long (mine is about 6 inches) so I think just beefing up the wires will work.Ebike Phase wires .jpgEbay Hi-Tempspade connectors 100amp.jpgEbike crimp disconnect .jpg
 
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Honestly I still think if the solder on the connectors is melting, it's at least partially the connector's fault. I wouldn't trust those type of spade connectors for more than 10A, also they are supposed to be crimped which would probably work, but regardless those style of spade connectors have a bad habit of losing their spring force that keeps them making good contact. Some MT60 or some 6-8mm proper bullet connectors would be a much better option.
 
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It's been many years since I Bought my 9C motor but I believe it was rated about 500W, don't know about amps. Loos like current wires phase wires from motor are solid core 14 gauge. Since I've had about half a dozen burnouts over the years it's certainly won't hurt to beef up the wires. I stumbled upon a poster here that tweaked his motor for a steep mountain climb /race and his main changes were to increase the wiring and add a cooling system to the motor. I\ll be reading that more intently later when I'm ready to open the motor.
 
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99t4 said:
Those can be tricky to solder well. Unless there is a good full solid bond the entire depth of the cups you can get heat problems from high resistance there.

What is your soldering method?
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Well with bullets there's only one way to solder. Fill the pool and then slowly remelt on wire. with the crimp on I do crimp first for stable position and then solder over it as the solder will wick in filling the gaps. I must say I understand what everyone is so leery of spade connectors..but these are different. As a matter of fact they are manufactureed with so tight a roll I had trouble connecting them and you'll see in the picture the connection stayed even after the heat was great enough to dislodge the wire.
 
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scianiac said:
Honestly I still think if the solder on the connectors is melting, it's at least partially the connector's fault. I wouldn't trust those type of spade connectors for more than 10A, also they are supposed to be crimped which would probably work, but regardless those style of spade connectors have a bad habit of losing their spring force that keeps them making good contact. Some MT60 or some 6-8mm proper bullet connectors would be a much better option.
Click to expand...
I tired barrels many times before and though I do like them they couldn't withstand the heat eventually melting away and charring to bits.
I used the 2 most common sized barrel and both of them bit the dust.
 
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scianiac said:
Honestly I still think if the solder on the connectors is melting, it's at least partially the connector's fault. I wouldn't trust those type of spade connectors for more than 10A, also they are supposed to be crimped which would probably work, but regardless those style of spade connectors have a bad habit of losing their spring force that keeps them making good contact. Some MT60 or some 6-8mm proper bullet connectors would be a much better option.
Click to expand...

endless-sphere.com

Please help diagnose a near meltdown

There's two parts to this issue, part one is a crash that damaged the hub motor cable, and part two is the discovery of a near melt down by the battery, which may have been caused by the crash, but might just be coincidence. Part 1: On my commute home a driver cut me off, which caused me to go...
endless-sphere.com endless-sphere.com
Same issue, but I think I'm reading that the goal is to change out the wires, not to choose the right connectors.
 
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NOt necessarily.. Different solders have different melting points...so while I knows these wires and connectors are getting dang hot at least this time is was only the solder that showed damage..not the connectors. Before with other types of connectors they did get mightily burned. I might be wrong but the evice doesn't so far reflect that. It won't hurt to switch out the wires first and see how it goes. And so far the only burning is the connectors that are near the motor as opposed to the connections near the controller.. So the motor must be getting might y hot and wicking that heat outward.
 
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