Hello all,

 

The attached picture shows the fuse box above the battery.  I have noticed that the black cable becomes very hot, and has at one point in time melted the plastic wall between itself and its neighboroughing red cable, causing what appears to be a short.  I have placed a bit of plastic between the two cables now; however, the black cable has melted its mount and has made some of its metal plates brittle to the point of breakage, so they obviously need replacing (they seem to be some sort of fuse plating).

 

Does anyone know what could cause this?  Perhaps a faulty alternator voltage regulator?

 

 

Also, the battery is no longer being charged (this is a brand new battery).  It starts off with 12.13 volts, then drops to 11.5x once the engine has started, and down to 11.3x when lights, stereo, heater, etc are turned on.  Even when the engine is rev'd to 1000 or 1200 rpm to maintain a constant voltmeter reading.  This tells me that the alternator may indeed have a faulty voltage regulator, or warn brushes, or warn shims, etc.

 

 

I looked at my Haynes manual to see how to remove the alternator and it seemed quite easy; however, the air conditioning compressor didnt want to come off, and the manual forgot to mention that a number of auxillery drive belt pulleys need to be removed in order to get to the alternators top mounting bolt, so I have been unable to remove it too.  :-(

Hello all,

The attached picture shows the fuse box above the battery. I have noticed that the black cable becomes very hot, and has at one point in time melted the plastic wall between itself and its neighboroughing red cable, causing what appears to be a short. I have placed a bit of plastic between the two cables now; however, the black cable has melted its mount and has made some of its metal plates brittle to the point of breakage, so they obviously need replacing (they seem to be some sort of fuse plating).

Does anyone know what could cause this? Perhaps a faulty alternator voltage regulator?

Also, the battery is no longer being charged (this is a brand new battery). It starts off with 12.13 volts, then drops to 11.5x once the engine has started, and down to 11.3x when lights, stereo, heater, etc are turned on. Even when the engine is rev'd to 1000 or 1200 rpm to maintain a constant voltmeter reading. This tells me that the alternator may indeed have a faulty voltage regulator, or warn brushes, or warn shims, etc.

I looked at my Haynes manual to see how to remove the alternator and it seemed quite easy; however, the air conditioning compressor didnt want to come off, and the manual forgot to mention that a number of auxillery drive belt pulleys need to be removed in order to get to the alternators top mounting bolt, so I have been unable to remove it too. :-(

The cable is getting hot 'cause there is high resticance somewhere on the circuit that is probably why the alt. output is low. Have you removed the cable from the fuse board and tried cleaning the terminals or checked the engine earth.

Believe me hot cables only come from high resistance or dead shorts.

Edited 9 October, 201312 yr by chrisw4266

Common fault with the Octavia im affraid, usually caused by the connection to the black aternator cable becoming loose at some point or corroded. This in turn creates high resistance through the cable and causes the cable to get hot and start to melt the fuse box. It looks as though u may have been lucky enough to have caught it early so that you do not need to replace the fuse box.

 

Initially I would try taking off the connection, cleaning it up thoroughly and and then securing tightly back in place monitor the problem. If the cable still gets hot then it will require a replacement alternator harness (Not a massive job).

 

I had the issue myself a few months ago and wasnt lucky enough to catch it before it damaged the connector on the fuse box. In the end I bypassed the fusebox on top of the battery completey with the alternator cable and rewired to a stand alone fuse block mounted in the engine bay. All has been well since.

 

Hope this info helps. If not there is tons of info around on the net and this site regarding the issue.

 

Cheers

 

Dazz

Thank you for your feedback Chris and Dazz.

 

The black cable on the alternator is a bit corroded and was secured with just a nut.  It had its plastic cover on still though.

 

I am thinking about adding a washer and smearing vaseline over the connector, as that is what I do to the battery terminals, or do you think vaseline isnt a good idea due to the higher voltage?

A poor crimp connection on the cable is the cause of the problem, & the best thing is to replace with a new cable. It's not an expensive part from TPS or a Skoda main stealer.

I second Paul on that a new cable would be best and would save any future worries.

Pretty sure the big cable from the starter motor also suffers from the same problem too.

Edited 9 October, 201312 yr by pauldazzle

Just a few helpful pointers:-

1.Where the wire connector/surrounding plastic is damaged and getting hot,is where the 'High' resistance is. Not in other places,in the car!. Other places may be the cause of the problem.

2.Vaseline is fine,technically the joint faces ,should be clean,tight,and without vaseline.The vaseline goes over the whole terminal,and crimp,to prevent corrosion.

3. Any  crimp connector,can become defective,after time , to elliminate this problem ,I would remove the cable from the car. Either a small gas flame,or a 100 watt soldering iron to heat the crimp,apply flux,and solder the cable to the crimp connector. This will make a better connection (lower resistance) than the original crimp,and will never go faulty again.

Edited 14 October, 201312 yr by AndyPandy

+1 for new cable buddy..... When it doubt chuck it out..

Hi Dazz, ref, Mk 1 Octy Diesel, have you a picture of your new wiring arrangement and fuse block, did you wire directly to battery or jointed at the nut connection on the existing fuse block?

My Alternator appears to be noisy now, hence my searching and finding a partially melted fuse block.

I have lost my security light which sits next to the door locking pin on the door trim? Could this have been a relatedto the over heating of the joint.

Thanks Ron

 

Gunna put these 2 cables on my to do list I think.... doh!! As if the list I've changed wasn't enough!! :-o lol

I have spare black cables.  One from battery clamp, and also the one from fuse box to alternator.

Did mine a few weeks ago. Replaced fuse box, cut cable back and recrimped end with new connector.

I keep checking it and so far it's not got hot.

Sent from my iPhone using Tapatalk

Sorry for the late reply guys.  My user profile got mangled last year and I have only just remembered that I had a user on this site. 

 

I fixed the problem by replacing the cable as suggested by you good folks. 

 

Thanks to everyone for your help. 

 

SK

Wow.. thats a while back alright!