motor to controller wires heating up when over 70% throttle

[void7775]

hi.
i've bought a golden motor which has the motor all black like this:
http://s2.postimg.org/w30b9qw3t/P1070304.jpg
1000w 48v. 20A controller.
i bought new lead 12v 18ah batteries. (initial current 5A)
i used the cables taken from the cord of something like this http://cdn.altex.ro/media/catalog/product/cache/1/image/600x/9df78eab33525d08d6e5fb8d27136e95/3/8/381.250k_-381.251k-_-381.25_1_1.jpg
they seem the same diameter as the motor power cables.
the wires from the battery are not getting hot at all while the 3 wires from the controller to the motor are getting hot if the wheel is stopped or if I apply the brakes hard to simulate a hill climb. the motor wires are original and came with the motor itself. they are going directly in to the motor.
the LCD also has a voltmeter. so I've put the bike wheel in the air and pushed the acceleration to the max.
the power bar is empty when I don't push the brakes. the power bar gradually goes up to full when I push the brakes (gradually to maximum). the voltage reads something like 48v when it's running without brakes. and when I push the brake that hard that it makes the wheel stop it drops to a minimum of 41v.
the wires of the battery are also heating up.
1.what cables should I use?
2.could it be the connections? I just use screw bolts to hold the wire pinned down to the battery connections.
i was pushing the brakes until the power meter got to about 70%. only then the wires started to be hot a bit.
3.why are the original cables of the motor also heating up? if the wires of the battery would be bad should only they be heating up?

 

[flangefrog]

What you need to understand is that the current flowing from the controller to the motor is actually not the same as the current from the battery to the controller. The controller acts like a buck converter and lowers the voltage while raising the current (watts stay constant). If you put 48V and 20A into the controller then at stall you may have 4.8V at 200A going into the motor. The exact amount depends on the motor's resistance and the controller's phase current limit. When the motor is turning it gets a little more complex as it acts as a generator - the voltage it generates is called Back EMF. At no load the back EMF is about the same as the battery voltage and results in almost no current flowing (except to cover core losses).

I'm not sure what country you're from and if it uses 110V or 220V AC but where I live the mains cable for a 4 way adapter is usually rated at 10A. As your system draws 20A from the battery and efficiency is more important on a bike I would go for something a little bigger.

Now as to why the motor wire supplied is getting too hot? I assume they have just not supplied wire that is capable of supplying the currents the motor needs at stall. It is a very bad idea to use the brakes to stall the motor as the high currents flowing can easily burn it out. Even when going up a hill you should pedal to keep the speed from dropping or back down on the throttle so the phase current doesn't get too high.

The connections wouldn't cause the wire to get hot. In fact, less current would be flowing through the wire and the connections themselves would get hot.

 

[macribs]

Get yourself some real cables meant for high Amp. The reason your wires heat up is that they are to small for the Amp you try to push through the wires. You are in the risk of fire. What you need if a beefier wire. Thick ones meant for high amperage. Like wires meant for car amplifiers. Thicker is better. Household wires will not work as you already seen.

 

[dogman dan]

Warm wires like that are normal, but not hot enough to melt.

You can make the wires warmer than normal, by overloading the motor, then the heat wicks out of the motor down the wires.

The standard easy fix for hotter than normal wires is to cut the wire close to the hub, 6 inches or so out, then replace all the fat wires with even bigger wire. 12g should be large enough. You DO NOT cut the small wires, leave those as they are.

This prevents any wire heating from the current, and also allows more copper mass to soak up heat that comes up the wire from the motor.

 

[d8veh]

If your motor wires are getting hot, it;s probably because you have the wrong phase/hall wire sequence. Is it the first time you've used the motor and controller combination?

 

[manman]

If your motor wires are getting hot, it;s probably because you have the wrong phase/hall wire sequence. Is it the first time you've used the motor and controller combination?

Hi I finally managed to get my controller to work it's a LD-BG-AK-007 I bought it about three months ago I thought it would be plug and play but no.
When I connected it to my bike running a 48v 750w Bafang rear hub motor G062 to my horror it made an awful noise a kind of whining and the pedal assist would only turn the motor after about 4 Revolution's also walk mode was really grinding,I read an article that maybe if you swapped two wires from the HALS side on the controller yellow and blue and reverse them and change the phase wire combinations.
So I did the phase wires blue to blue and yellow to green and green to yellow and hey presto the thing works although walk mode is running at 11km pedal assist works but I noticed that the phase wires were getting warm the controller is a 25A 48v .any help please or is this normal .

 

[manman]

Yes it's the first time I've been trying to get this controller to work for about 2 months so today I read about swapping wires around.

 

[manman]

I've tried every combination with phase wires and with correct combination on the HALS connector but that is not working,but when I changed the combination on the HALS yellow and blue reversed and like I said earlier phase wires blue to blue green to yellow and yellow to green .it's the only combination I have found that works,but like I said I noticed the phase was getting warm not hot

 

[AGS]

Use this template when swapping the wires around. There are 36 possible combinations and only one will work properly. You may find that with a couple of combinations the motor spins, but draws excessive current, which is what you may be experiencing.

If your display measures watts then you can measure the unloaded watts while you are testing.

 

[manman]

Use this template when swapping the wires around. There are 36 possible combinations and only one will work properly. You may find that with a couple of combinations the motor spins, but draws excessive current, which is what you may be experiencing.

If your display measures watts then you can measure the unloaded watts while you are testing.

View attachment 358283

Hi thanks I followed this diagram

 

[manman]

The smooth rotation works all the other combination's just made grinding noise or a whiring sound.im not that technical to try 36 different combinations.

 

[E-HP]

The smooth rotation works all the other combination's just made grinding noise or a whiring sound.im not that technical to try 36 different combinations.

Since it's a geared hub, the whirring noise is likely the motor spinning backwards (wheel doesn't turn because of the clutch). I'd try to replicate the whirring (not grinding) noise, then follow the steps to reverse the motor direction (see chart halfway down the page):

Testing BLDC motor's Phase Wiring - Hall Sensors and Wiring. - Electricbike.com Ebike Forum

Testing electrical components of a typical hub motor with a digital multi meter. First take a few minuets and look over the wiring going into the motor for cuts, scrapes, missing insulation and other wiring issues or poor connections that should be resolved first. Smell for...

electricbike.com

 

[manman]

Hi so i used the diagram from tomycat and the 3rd smooth rotation on the left of the diagram works but it seems the phase wires are getting warm as I said before I've swapped the green and yellow wires on the HALS connector and the phase sequence is the same as the diagram on the smooth rotation blue to blue yellow to green green to yellow,now should I reverse the green signal wire in the HALS connector as of now I've only reversed two yellow and blue.

 

[AGS]

Ebike motors use teflon coated wires. It looks like you are using pvc coated wires.

Teflon coated wires mean that you can run thinner gauge wire into the motor than you can with ordinary pvc coated wires.

Teflon wiring can operate at a maximum temperature of around 260C whereas pvc wiring can only tolerate around 105C.

Your phase current is probably approaching 60 amps and you are using wiring rated at 13 amps.

 

[manman]

So if I understand correctly that the phase wires pvc coating is not enough for the protection of the wires,and maybe that's why they are getting warm what is the solution, without opening the controller and putting new gauge wires on the controller.i spliced the original cable to expose the 3 phase wires and 6 HALS connectors so I could connect directly to the controller.

 

[E-HP]

Probably should have started with pics and on a separate thread. The problem with hijacking an old thread is that it confuses the facts, assuming the situations and/or equipment is the same/similar. The controller in the pic appears to be a KT controller with the integrated motor plug. From what I’ve read on this forum, it’s very rare to have a mismatch with that plug with a bafang motor using the corresponding plug. A complete list of your system components and pics might help figure out what the real problem is.

 

[manman]

Use this template when swapping the wires around. There are 36 possible combinations and only one will work properly. You may find that with a couple of combinations the motor spins, but draws excessive current, which is what you may be experiencing.

If your display measures watts then you can measure the unloaded watts while you are testing.

View attachment 358283

don't understand this chart i can't figure out what I'm supposed to do I know how to swap the wires but I a little confused

 

[manman]

Use this template when swapping the wires around. There are 36 possible combinations and only one will work properly. You may find that with a couple of combinations the motor spins, but draws excessive current, which is what you may be experiencing.

If your display measures watts then you can measure the unloaded watts while you are testing.

View attachment 358283

I don't understand the diagram I don't understand the arrows and which are phase and which are HALS could you explain in lamens terms please.