Why are my phase wires melting??

E

ebike11

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Hi guys
This is the second time Ive encountered this on my Bafang 8fun motor. I extended my phase wires by soldering
silicone wire to reach my controller mounted on my frame. The silicone wire is rated 200 degrees and I used xt60 connectors to my controller.
Today when riding the wires melted the wire jackets completely off in some areas.
Controller is at 30amps and battery is 72V.
Any ideas?? Thanks!
 
You melted the insulation of the silicone wire you added? What size is the conductor (AWG)? It sounds like its far too small.

Remember that phase current can be 2-3 times battery current...
 
Punx0r said:
You melted the insulation of the silicone wire you added? What size is the conductor (AWG)? It sounds like its far too small.

Remember that phase current can be 2-3 times battery current...
Click to expand...

Yes I melted the insulation arggggg....

What size do you suggest for bafang 8fun phase wires? The bafang wires are really stiff but not
that thick of guage.
Thanks
 
Did you melt the wire insulation or the plastic shrouds over the bullet connectors? Can you explain what you mean by "wire jackets".

If the melting happens at the connector, you have too much contact resistance. Chuck the connectors and solder the wires directly.
 
Ah by wire jacket i meant insulation. The wires didnt melt specifically at the connectors, just the length in between the bafang phase wires and connectors. Since I used xt60s it has been better than before. I think Ill need to get thicker wire first
 
xt60 are 2 pins. how do you use it for 3 wires? i would not take xt60 - i use them for controller to battery only, and here they work fine. for motor to controller i use 5.5mm bullet connectors. they won't melt for sure.
the connectors get hot when they have a loose fit, and when connection surface is small. so the bigger and stiffer a connection is, the cooler it will run.
 
What gage wire? I find it amazing if you melted 12 g. 30 amps of 72v is enough to warm 12g enough to feel it, but I never melted any. Melted connectors but never the wire itself.
 
izeman said:
xt60 are 2 pins. how do you use it for 3 wires? i would not take xt60 - i use them for controller to battery only, and here they work fine. for motor to controller i use 5.5mm bullet connectors. they won't melt for sure.
the connectors get hot when they have a loose fit, and when connection surface is small. so the bigger and stiffer a connection is, the cooler it will run.
Click to expand...

Ah, I put an xt60 on each phase wire...yes I think its overkill but since I had them. I had no bullet connectors around
 
dogman said:
What gage wire? I find it amazing if you melted 12 g. 30 amps of 72v is enough to warm 12g enough to feel it, but I never melted any. Melted connectors but never the wire itself.
Click to expand...

would 10 guage be overkill??? I need to up the wire thickness
 
something else is going on. this guy never includes pictures so now i am suspicious of what he is talking about. i think he also reversed the phase and hall wires from the stock colors too. hard to know in a vacuum.
 
dnmun said:
something else is going on. this guy never includes pictures so now i am suspicious of what he is talking about. i think he also reversed the phase and hall wires from the stock colors too. hard to know in a vacuum.
Click to expand...
yes. pictures would be nice. a pictures says more than 1000 words.
 
dnmun said:
something else is going on. this guy never includes pictures so now i am suspicious of what he is talking about. i think he also reversed the phase and hall wires from the stock colors too. hard to know in a vacuum.
Click to expand...

You must be the psychologist of the forum... ok Ill post pictures of burned wire insulation asap if it makes you happy. Nothing else is going on here...I wouldnt waste everyones time if what I said didnt happen
 
look, you want us to help you so you come here and ask for help.

you did not post up any pictures or useful information that we can use to help you. so why bother if there is no way we can get enuff information to even know what you are doing or what kinda equipment that you have?

it is already clear you are capable of igniting the lipo with that high voltage charger and had another thread where you said you reversed the phase wires from stock colors. so when you ask for help, most people who don't follow all of these threads you started and do not have a clue about any of these other unknowns.

sure you get free advice but most don't have a clue about what it is you are doing.

if you have emotional problems related to showing your work then you need to get into counseling first to get over it if you wanna talk to others who do this stuff and know what they are looking at that you wanna hide.
 
You still haven't answered what gauge wire was on there. You're asking a question without complete background and when asked for the full picture, you question the request. Not a good start for a noob.

Post up FULL DISCLOSURE of what you did and someone will figure out what went wrong and help you in the right direction.
 
You need to replace the wires all the way into the motor. That's because the insulation is quite likely to be damaged inside the axle too. Increasing the wire gauge to whatever you can fit through the axle is always a good thing.

cal3thousand is getting on your case because you've been incomplete regarding your info. We don't know what your wires were, but it's quite possible that they were big enough and you ran it with an incorrect wiring combination which can resulting in over-current and lots of heat. You can verify correct wiring by measuring the current from the battery at WOT with the wheel off the ground.

Also, it's a good idea to check for heat often in those initial test rides. Stop and feel for heat in the wires, controller, motor, and occasionally even the battery. Heat is the enemy, and if you went so far as to melt the insulation off of you phase wires, then consider yourself very lucky that you didn't blow the controller or damage the motor.

I don't know which Bafang you have, but they limit most of their ebike motors to 20A or less. Yes you can get away with pushing them harder, but you can't just add a 30A controller and think it's safe for all conditions and loads. The harder you push any part of an ebike system, the more you need to be aware of its limits and what conditions are more stressful. Any system can be pushed to heat failure, but even the cheapest systems can be run reliably.
 
If you are talking about the Bafang BPM, I have doubled the stock phase wires inside the hollow axle, and I was surprised at how easy it was to do. As far as the wires that are outside the axle, if they are slightly fatter than the doubled axle phase wires, then they typically shouldn't be a heat issue. http://endless-sphere.com/forums/viewtopic.php?f=16&t=51237#p758156

You have mentioned 30-amps. If it is flat land, there is a possibility that you may draw 30 amps during the short acceleration to cruise speed. Once you attain your top speed on relatively flat land, the amps drawn will slide down into a range that is lower (just enough to maintain the load).

However, if you ride your bike on very long and steep uphills, you can theoretically draw the max allowed amps constantly. 10-ga should be fatter than doubled stock BPM phase wire. It's also possible that the battery amps are set to 30A, but...the phase amps are set much higher.

Since something is going on that you might not understand, its actually true that pics will help diagnose this. Best of luck...
 
spinningmagnets said:
If you are talking about the Bafang BPM, I have doubled the stock phase wires inside the hollow axle, and I was surprised at how easy it was to do. As far as the wires that are outside the axle, if they are slightly fatter than the doubled axle phase wires, then they typically shouldn't be a heat issue. http://endless-sphere.com/forums/viewtopic.php?f=16&t=51237#p758156

You have mentioned 30-amps. If it is flat land, there is a possibility that you may draw 30 amps during the short acceleration to cruise speed. Once you attain your top speed on relatively flat land, the amps drawn will slide down into a range that is lower (just enough to maintain the load).

However, if you ride your bike on very long and steep uphills, you can theoretically draw the max allowed amps constantly. 10-ga should be fatter than doubled stock BPM phase wire. It's also possible that the battery amps are set to 30A, but...the phase amps are set much higher.

Since something is going on that you might not understand, its actually true that pics will help diagnose this. Best of luck...
Click to expand...

Thanks for the helpful info and link!
Actually Ill try to move the controller to the rear and connect the phase wires directly to my 30A shunt modded ku93.
I noticed that eventhough the bafang wires arent that beefy, they seem stiff and dont cause any melting issues.
Usually it was the soldered 14 and 16guage wire that had the insulation burned off. If I extend the phase wires in the future, ill use 10 guage to be safe
 
did you have this problem with the overheating phase wires when you had the phase wires of the same color connected before you decided to swap them?

i would recommend you try to see if the current is still so high when you use the colors of the phase wires matching each other like it came from the factory.

if the phase wires still overheat then it will be worth investigating.
 
There you go, just a case of too thin wire IMO. But the advice you got is good, the extra heat may have damaged the wire all the way into the motor. But if the stock wire looks ok, just cut it to a few inches from the hub, and splice on fat wire from there. The fat wire will actually heat sink the wire in the hub some.

10 g should do er for sure.
 
dogman said:
There you go, just a case of too thin wire IMO. But the advice you got is good, the extra heat may have damaged the wire all the way into the motor. But if the stock wire looks ok, just cut it to a few inches from the hub, and splice on fat wire from there. The fat wire will actually heat sink the wire in the hub some.

10 g should do er for sure.
Click to expand...

Ok ill try soon
 
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