Hot motor cable on G Wiz AC controller

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Jimblob
Posts: 4
Joined: Sat Apr 09, 2011 11:38 am

Hot motor cable on G Wiz AC controller

Postby Jimblob » Mon Apr 16, 2012 3:04 pm

Hi chaps
Firstly, apologies if this post is in the wrong section.

Can anyone give me a clue as to what is wrong? I have a working G Wiz with the AC controller but one of the 3 power cables to the motor gets incredibly hot and has melted its insulation at the controller end. It creates a bad smell whilst driving!

I've measured the resistance of the cable, on my multimeter at 0.04 ohms, I don't think the cable is to blame as the other 2 (which have not melted) measure the same but perhaps I'm wrong and should change it? My initial thought was that the cable must have unusually high resistance, therefore causing the heat.... Perhaps it's the controller itself that is faulty?

Bit stuck.... any good clues from experience would be massively appreciated!

Jamie

DSC_0011_ small.jpg
You can see the blackened cable....
DSC_0011_ small.jpg (30.91 KiB) Viewed 26667 times
http://www.ElectricBikeSales.co.uk
Cambridge (me) - Oxford - London - Bristol
... please note that I write on this forum in a personal capacity... ebikes = business... ecar = toy!

Jimblob
Posts: 4
Joined: Sat Apr 09, 2011 11:38 am

Re: Hot motor cable on G Wiz AC controller

Postby Jimblob » Mon Apr 16, 2012 5:17 pm

Having swapped the cables round the blackened one is the one overheating whichever of the 3 phases it's connected to...
So I think the cable must be fault in some way. Anyone know the best place to get good 400A cables, about 20cm in length, crimped?
http://www.ElectricBikeSales.co.uk
Cambridge (me) - Oxford - London - Bristol
... please note that I write on this forum in a personal capacity... ebikes = business... ecar = toy!

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dillond666
Posts: 139
Joined: Mon May 26, 2008 7:52 pm
Location: Central Scotland

Re: Hot motor cable on G Wiz AC controller

Postby dillond666 » Tue Apr 17, 2012 8:28 pm

Perhaps an industrial welding supply shop, they could crimp the ends on a bit of welding cable for you.
You can also get the cable, lugs and a hydraulic crimper on ebay if you fancy a shot yourself.

D

Jimblob
Posts: 4
Joined: Sat Apr 09, 2011 11:38 am

Re: Hot motor cable on G Wiz AC controller

Postby Jimblob » Fri Apr 20, 2012 9:10 am

Hi Chaps. I managed to get hold of 3 x 20cm cables of suitable thickness. I thought I'd do away with the ring (induction ring?).
However the motor wouldn't work without it........... why?
Anyhow with the 2 good original cables around the induction ring and one cable going direct to the controller it works... but I'm puzzled as to why I need to wind the cables around this ring. I thought the ring was just there to reduce electromagnetic interference.
J.
http://www.ElectricBikeSales.co.uk
Cambridge (me) - Oxford - London - Bristol
... please note that I write on this forum in a personal capacity... ebikes = business... ecar = toy!

JonSpence
Posts: 74
Joined: Thu Jan 03, 2008 1:05 pm
Location: Rochdale

Re: Hot motor cable on G Wiz AC controller

Postby JonSpence » Sat Apr 21, 2012 5:08 pm

Jimblob wrote:Hi Chaps. I managed to get hold of 3 x 20cm cables of suitable thickness. I thought I'd do away with the ring (induction ring?).
However the motor wouldn't work without it........... why?
... but I'm puzzled as to why I need to wind the cables around this ring. I thought the ring was just there to reduce electromagnetic interference.
J.


That ring is known as a choke and modifies the NASTY square waves produced by the inverter. You are quite correct in thinking that one of it's main purposes is to reduce EMI. However it does slightly more than that. It stores and releases energy, modifying the waveforms seen by the motor into something a lot closer to sine waves. Please don't try to run without it.

You are actually quite lucky that it didn't "work" and would have been unlucky if it did. You see it is quite likely that not only were you beating the motor with VERY high voltages during the edges of those square waves but that you were inducing a current flow through the bearings which would destroy them quite quickly.

Try a google on the subject, something like this
http://www.google.co.uk/search?hl=en&sc ... hoke&btnG=

JonSpence
Posts: 74
Joined: Thu Jan 03, 2008 1:05 pm
Location: Rochdale

Re: Hot motor cable on G Wiz AC controller

Postby JonSpence » Sat Apr 21, 2012 5:15 pm

OOps, I just re-read this bit

Jimblob wrote:Anyhow with the 2 good original cables around the induction ring and one cable going direct to the controller it works...


I greatly fear that you may be introducing problems by only having chokes on 2 of the three phases. That ring is three chokes. You might want to rewind the 3'ed leg and then get the lugs crimped on.


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