Wires getting hot and insulation melting

Get all your technical information about electric bikes here.

Wires getting hot and insulation melting

Postby wayner » Mon Sep 18, 2017 8:20 pm

My wife bought an electric 3-wheeled bike. It is kind of a Pedicab with an electric motor driving the front wheel - and you can also pedal. The bike would be quite a bit heavier than a typical two wheeled bike.

The controller for the motor is a generic 800W -48V controller. A couple of times now after using the bike for a bit the motor would cut out. I would examine the wiring, which is a bit of a rat's nest and notice that the wires are very hot and it appears that some of the wire insulation has melted at times, shorting out the wires. This appears to be the green and blue motor phase wire that are the hottest.

Any idea why this would be happening? Would the controller be trying to push too much current for the size of the wires? Any suggestions on what to do to fix this. Is the controller undersized for the weight/size of the bike.

Here are some pictures:
ebike controller.jpg
(174.5 KiB) Downloaded 33 times

ebike motor.jpg

ebike.jpg
wayner
1 µW
1 µW
 
Posts: 4
Joined: Mon Sep 18, 2017 8:08 pm

Re: Wires getting hot and insulation melting

Postby Jon NCal » Mon Sep 18, 2017 9:43 pm

The picture does not really show where the wires are melting. Sometimes the connectors are too small and heat up a lot and melt the insulation. If that is the case, one solution is to remove the connectors and splice (solder) the wires together.
Jon NCal
1 kW
1 kW
 
Posts: 322
Joined: Mon Jun 15, 2015 3:59 pm
Location: Mendocino, California

Re: Wires getting hot and insulation melting

Postby wayner » Mon Sep 18, 2017 10:03 pm

The wires are just twisted together and then taped over with electrical tape. For the most part that is how the wires are connected on this bike. But the electrical tape was melting as well as some of the insulation. Should I solder the wires together, or use a crimped butt connector, or something else?
wayner
1 µW
1 µW
 
Posts: 4
Joined: Mon Sep 18, 2017 8:08 pm

Re: Wires getting hot and insulation melting

Postby Jon NCal » Mon Sep 18, 2017 10:48 pm

Do a proper splice by interleaving the strands and then wrapping some fine copper strand around. Then solder. Oh, don't forget to put the heat shrink tubing on before joining up the wires.
Last edited by Jon NCal on Tue Sep 19, 2017 12:04 pm, edited 2 times in total. View post history.
Jon NCal
1 kW
1 kW
 
Posts: 322
Joined: Mon Jun 15, 2015 3:59 pm
Location: Mendocino, California

Re: Wires getting hot and insulation melting

Postby amberwolf » Mon Sep 18, 2017 11:19 pm

Ditto. If the connection is poor, there will be high resistance, whcih causes heating under load.

There's a number of good ways to splice the wires together that won't have this result. Here's one instructable, which itself has other ways in it's comments section
http://www.instructables.com/id/Master- ... everytime/
and google searches will find others.

My favorite splice for thick multistrand cables is to
--cleanly cut the wires to be spliced
--slide a 2" or longer piece of heatshrink over each of the wires, and leave them pushed back as far as possible from the splice point.
--strip the insulation off a short distance (1/2" to 1" depending on what I'm splicing--bigger it is the farther back I strip)
--slightly spread the individual strands apart, like the end of a broom
--insert one set of strands into the other, so they are interleaved.

If i have a crimper that will do the job, I'll crimp the strands together to make a solid connection.

If I don't, I'll twist the strands so they are pressed together as well as possible, then tightly wrap a single strand of copper from some other cable (cat-5 network stuff works well) around the splice point to hold the strands together.

Then either way, I'll solder them.

Then I'll wait for it to cool, slide one of the two heatshrink sections over the splice, and heat that to shrink it. Then wait for it to cool and repeat with the other one over the top of that one.


Additionally, if I have multiple wires in one cable to splice (like 3 phase wires), I'll offset each cut so that none of the splices overlap each other. Then even if the splice insulation fails tehy can't short to each other.
Last edited by amberwolf on Mon Sep 18, 2017 11:20 pm, edited 1 time in total. View post history.
User avatar
amberwolf
100 GW
100 GW
 
Posts: 23518
Joined: Mon Aug 17, 2009 6:43 am
Location: Phoenix, AZ, USA, Earth, Sol, Local Bubble, Orion Arm, Milky Way, Local Group

Re: Wires getting hot and insulation melting

Postby dogman dan » Tue Sep 19, 2017 6:56 am

Yes, poor connection on the big wires that go to the motor.

Replace with either 4 mm gold bullets from the radio control toys web store, or Anderson 45 amps power poles.

Or just make a permanent solder connection, soldered or using a crimp connector. It just needs to handle at least 30 amps if you use an automotive crimp connector. Big fat one.

Bullets solder, power poles can be crimped, so that might drive your choice.
Last edited by dogman dan on Tue Sep 19, 2017 6:58 am, edited 1 time in total. View post history.
User avatar
dogman dan
100 GW
100 GW
 
Posts: 34166
Joined: Sat May 17, 2008 12:53 pm
Location: Las Cruces New Mexico USA

Re: Wires getting hot and insulation melting

Postby speedmd » Tue Sep 19, 2017 7:46 am

Hand twist will not do it. Wire nut at least. If it is just a few of the wires and the connections are solid, it may be hall - phase wire mix up. Does it run perfectly smooth and quiet? Sometimes hard to tell. If the controller has a self learn option, you may want to run it if all else is solid.
Last edited by speedmd on Tue Sep 19, 2017 7:48 am, edited 1 time in total. View post history.
User avatar
speedmd
100 MW
100 MW
 
Posts: 2699
Joined: Wed Nov 14, 2012 12:16 pm
Location: new england

Re: Wires getting hot and insulation melting

Postby wayner » Tue Sep 19, 2017 8:01 am

Thanks everyone - this weekend I will take your advice and solder these together. Is it not recommended to use shrink-wrapped butt connectors?

There isn't a ton of wire to play with - if you look at the first photo (which for some reason doesn't display inline) you will see that there are only about 2" of the green, blue and yellow wires which I believe are the motor phase wires.

Other than this the bike works fine. Would it be obvious if there was an issue for the wiring of the hall sensors?

Anyone have any comments on whether the controller, which is one of the cheap, generic Chinese 800W controllers, has enough power for a bike of this size. The bike is fairly heavy and the batteries are lead-acid - each of the four 12V batteries is roughly half the size of a typical car battery.
wayner
1 µW
1 µW
 
Posts: 4
Joined: Mon Sep 18, 2017 8:08 pm

Re: Wires getting hot and insulation melting

Postby Rassy » Tue Sep 19, 2017 9:52 am

Thanks everyone - this weekend I will take your advice and solder these together. Is it not recommended to use shrink-wrapped butt connectors?


You have lots of good advice to pick from, but still asked about butt connectors. I like to use butt connectors, particularly on the 10 and 12 (Yellow connectors) gauge wires. Obviously you can't solder them after crimping so here's what I do. Mix up a little silver conductive epoxy and apply a small amount using a toothpick inside the butt connector and to the wire, insert the wire, and crimp. This results in a good mechanical connection with the crimp and a good electrical connection with the epoxy. I usually let it set up overnight before putting any stress on the connection.

I've used this method for years and never had a failure. The down side is that the silver conductive epoxy is quite expensive, but you just use a very small amount at a time. If used where you can see it afterwards it looks just like you had soldered the connection.

https://www.amazon.com/MG-Chemicals-Two ... B008UH4DB2
Last edited by Rassy on Tue Sep 19, 2017 10:35 am, edited 1 time in total. View post history.
-Rassy-
One Tadpole Trike equipped with a Bafang BBS02
viewtopic.php?f=28&t=69419
One Delta Trike equipped with a Bafang BBS02
viewtopic.php?f=28&t=88536&p=1291260#p1291260
User avatar
Rassy
1 MW
1 MW
 
Posts: 1891
Joined: Sun Apr 08, 2007 10:58 am
Location: Eugene, Oregon USA

Re: Wires getting hot and insulation melting

Postby spinningmagnets » Tue Sep 19, 2017 10:02 am

Lithium is so much better from a performance and life-cycle perspective, that...sealed lead acid / SLA gets no love here.

That being said, they remain the cheapest purchase price pack. If you are truly happy with the performance of the motor and controller, the best upgrade when your current battery dies is an upgrade to lithium.
Last edited by spinningmagnets on Tue Sep 19, 2017 10:03 am, edited 1 time in total. View post history.
User avatar
spinningmagnets
100 GW
100 GW
 
Posts: 10674
Joined: Fri Dec 21, 2007 10:27 pm
Location: Ft Riley, NE Kansas

Re: Wires getting hot and insulation melting

Postby Drunkskunk » Tue Sep 19, 2017 5:49 pm

wayner wrote: Is it not recommended to use shrink-wrapped butt connectors?

There isn't a ton of wire to play with .... there are only about 2" of the green, blue and yellow wires which I believe are the motor phase wires.

Other than this the bike works fine. Would it be obvious if there was an issue for the wiring of the hall sensors?

Anyone have any comments on whether the controller, which is one of the cheap, generic Chinese 800W controllers, has enough power for a bike of this size. The bike is fairly heavy and the batteries are lead-acid - each of the four 12V batteries is roughly half the size of a typical car battery.


Neat bike.

-Those crimp connectors are ok, but they aren't the ideal connection. a soldered connection would be better.

-When you splice the wires, It's easy enough to add in another 6 inches to a foot of wire. And you probably should. your motor's wire goes straight down the fork into the motor. that means any water that splashes or drips on the fork or wire will run down the wire and into the motor. Propper instalation would include a drip loop- a short section of the wire that heads down out of the wire before going up the fork, so running water drips off the loop instead.

Image

-if the halls had an issue, the bike wouldn't go. It's possible that the melted motor wires (Blue, green, yellow) can melt the near by hall wires' insulation. best to check them for damage and re-insulate them if needed.

That controller is small, but it's not the controller's fault that the wires are melting. That's coming from undersized wires or a wrong speed motor. Some of these motors come with very thin gauge wire that would be fine for a lightweight bike that never sees a hill, but can't take the amps needed to lug heavy weight of a 2 or 3 passenger bike around. Often the motor is up to the job, but the wires aren't.
Also, If the bike has a motor with an RPM too high for it's application, then it will draw more power than needed trying to haul That will melt wires, and also cause the motor to get very hot.
You can test that 2 ways. (1) feel the motor. if it's very hot, you have a problem. (2) get a speedometer. a cheap walmart thing is fine. check the speed of the motor when you're riding flat out on a straight flat road. then check the speed again with the wheel held off the ground. the off the ground speed will be faster. the top speed should be 3/4ths of that speed, roughly. if it's much less, the motor might not be matched to your needs.

If the motor stays cool in spite of the melting wires, the problem is all in the wire.
Last edited by Drunkskunk on Tue Sep 19, 2017 5:51 pm, edited 1 time in total. View post history.
Buy the ticket, take the ride.
Monster Bike:http://endless-sphere.com/forums/viewtopic.php?f=6&t=38667
User avatar
Drunkskunk
100 GW
100 GW
 
Posts: 6989
Joined: Sat Apr 14, 2007 11:37 am
Location: Dallas, Texas. U.S.A.

Re: Wires getting hot and insulation melting

Postby wayner » Tue Sep 19, 2017 7:25 pm

Thanks drunkskunk- tons of useful info in your post.
wayner
1 µW
1 µW
 
Posts: 4
Joined: Mon Sep 18, 2017 8:08 pm

Re: Wires getting hot and insulation melting

Postby teklektik » Tue Sep 19, 2017 7:31 pm

wayner wrote:I would examine the wiring, which is a bit of a rat's nest and notice that the wires are very hot and it appears that some of the wire insulation has melted at times, shorting out the wires. This appears to be the green and blue motor phase wire that are the hottest.
wayner wrote:Other than this the bike works fine. Would it be obvious if there was an issue for the wiring of the hall sensors?

Frankly, this is where I would start before going down the 'solder everything together' route - particularly since you have limited wire length for a later redo. FWIW, I would recommend that you invest in some Anderson Power Pole or RC bullet connectors for the power and phase leads instead of soldering everything together - but that's a service consideration.

Most importantly: did you figure out the proper phase and hall combination?

It's extremely unlikely that your motor will run properly if you just match up the phase and hall wire colors. The symptom would be excessively large phase currents and perhaps melted insulation. Since you have a couple of particularly hot wires it sounds like two of the phases are working harder than they should which may suggest a bad phase/hall mix.

Also - the business of shorting out wiring is a little unsettling. You say it 'works fine', but I think it would be worth going through the motions of checking out if your controller is still healthy before you finalize wiring with solder. A short may have taken out the yellow phase FETS (which might be why that wire isn't heating up). Take a look at this post for a quick "no meter required" way to check your controller FETs. There's lots of stuff here on ES and I'm sure others will chime in with suggested reading or techniques...

Anyhow - basic advice is to verify your controller health and proper wiring before committing to an all-solder connection scheme that will pretty much preclude diagnostics once in place.
Last edited by teklektik on Tue Sep 19, 2017 8:31 pm, edited 1 time in total. View post history.
Visit Grin Technologies at www.ebikes.ca
Build Thread: 2WD Yuba Mundo V4
User avatar
teklektik
1 GW
1 GW
 
Posts: 3447
Joined: Sat Mar 26, 2011 1:15 pm
Location: CT, USA

Re: Wires getting hot and insulation melting

Postby dogman dan » Wed Sep 20, 2017 6:59 am

You can use the automotive butt connectors ( properly crimped or soldered) to gain an inch, or solder in some more wire to get more inches.

Main thing is you need the butt connector to be the big one, able to handle 30 amps, preferably even more.

Your wires will still always get very warm, because that hub motor is horribly overloaded when three people are aboard, and there is even an inch of uphill. But they should stop getting so hot they melt.

With the wires sorted, its the motor that will now run long enough to overheat, if overloaded enough. :roll:
User avatar
dogman dan
100 GW
100 GW
 
Posts: 34166
Joined: Sat May 17, 2008 12:53 pm
Location: Las Cruces New Mexico USA

Re: Wires getting hot and insulation melting

Postby izeman » Wed Sep 20, 2017 11:54 am

Rassy wrote:...Obviously you can't solder them after crimping so here's what I do....

sure you can - depending on the length of the crimp. hot solder will suck into the joint quite easily. a 1cm/half inch joint can be "after crimp soldered" w/o any problems. still i prefer the method of sticking the wires together, wrap in solid wire and solder all together.

2014-12-31 at 12.47.43.JPG
2014-12-31 at 12.47.43.JPG (97.86 KiB) Viewed 190 times


here the whole wire was stripped as the silicone insulation was to thick, and it got a layer of heat shrink only.
User avatar
izeman
10 GW
10 GW
 
Posts: 4465
Joined: Tue Jun 21, 2011 8:25 am
Location: vienna, austria

Re: Wires getting hot and insulation melting

Postby Rassy » Wed Sep 20, 2017 1:04 pm

Rassy wrote:
...Obviously you can't solder them after crimping so here's what I do....

izeman wrote:
sure you can


Sorry, I wasn't clear. I was talking about the insulated crimp style butt connectors where all you have when finished is your insulated wire sticking a little ways into the butt connector insulation.
-Rassy-
One Tadpole Trike equipped with a Bafang BBS02
viewtopic.php?f=28&t=69419
One Delta Trike equipped with a Bafang BBS02
viewtopic.php?f=28&t=88536&p=1291260#p1291260
User avatar
Rassy
1 MW
1 MW
 
Posts: 1891
Joined: Sun Apr 08, 2007 10:58 am
Location: Eugene, Oregon USA

Re: Wires getting hot and insulation melting

Postby izeman » Thu Sep 21, 2017 5:34 am

Agreed :). I try to avoid this type. I just don‘t trust them. Maybe they work fine still. For me crimping is fine (and prefered) for hall/throttle connector and stuff. Everything else is soldered (xt60, bullet etc...)
User avatar
izeman
10 GW
10 GW
 
Posts: 4465
Joined: Tue Jun 21, 2011 8:25 am
Location: vienna, austria

Re: Wires getting hot and insulation melting

Postby dogman dan » Thu Sep 21, 2017 6:43 am

A good crimp beats solder, however, betcha the crimp connector at the auto parts place is not capable of that good a crimp. Its fine for your stereo, or the extra off road lights, or the trailer lights, but the motor pulls a lot more power constantly.

Producing a perfect crimp takes an expensive tool, and the right connector, or a great deal of skill with a cheap tool. You will get a shitty crimp just squashing that connector with pliers.

Solder that connection generally much more dependable for most people. That's part of why I suggested the RC hobby gold plated 4 mm bullet connector. they are fairly easy to solder on the wire. And it will lengthen the wire an inch.
User avatar
dogman dan
100 GW
100 GW
 
Posts: 34166
Joined: Sat May 17, 2008 12:53 pm
Location: Las Cruces New Mexico USA

Re: Wires getting hot and insulation melting

Postby speedmd » Thu Sep 21, 2017 6:54 am

I often use copper tubing for butt crimps. I solder them also when concerned of max long term durability. Solid Mechanical is the best electrical connection but most can let in and trap moisture in areas that will potentially lead to corrosion. Solder is good at keeping things hermetic and not to rely on as a high current low resistance electrical path.
Last edited by speedmd on Thu Sep 21, 2017 12:50 pm, edited 2 times in total. View post history.
User avatar
speedmd
100 MW
100 MW
 
Posts: 2699
Joined: Wed Nov 14, 2012 12:16 pm
Location: new england

Re: Wires getting hot and insulation melting

Postby izeman » Thu Sep 21, 2017 7:31 am

problem with soldering is not physical strenght but the changeover from soldered to non soldered copper braid. braids breaks much more easily that way. if you crimp the wire, it should stay way more flexibel at the connection point. not that i had any issues with it yet. ;)
User avatar
izeman
10 GW
10 GW
 
Posts: 4465
Joined: Tue Jun 21, 2011 8:25 am
Location: vienna, austria

Re: Wires getting hot and insulation melting

Postby 999zip999 » Thu Sep 21, 2017 11:58 am

For phase wires 4mm gold plated bullets a 45 watt solder iron or more.
999zip999
100 GW
100 GW
 
Posts: 8086
Joined: Sun Jan 10, 2010 1:40 pm
Location: Dana Point So. Cal


Return to E-Bike Technical

Who is online

Users browsing this forum: No registered users and 9 guests