Battery issues, Fuse Box melting

[Bowders1]

Hi Folks if you have ever experienced a hot black lead from Alternator to fuse box or even melting of fuse box, chances are that you have the common poor resistance issue found across most of the VAG range of cars.

This could start life by a loose connection between crimp and battery terminal that will start a poor resistance which you may be lucky and can just clean the crud and wire brush the connector tighten up and all ok.

Then if left loose too long or not noticed will then progress to poor resistive connection between the crimp and the cable even if terminal are tight as the crimp will of had resistance damage.

Be warned, if you leave it you will melt your battery fuse box and potentially cause arching to your bonnet if there is any contact or fuse box gets moved from the plastic holder.

As the alternator is drawing 110A through the battery and loose connection will start the resistance issue. Once you have that issue it is hard to eradicate without fully changing the alternator lead(around £40)

As the crimp will of got very hot and blackened(like mine did) it was beyond fixing.

Also my fuse box had badly melted

I did a slightly cheaper mod. (well free actually off a spare fuse box that i also used))

As it is the crimp that suffers.(and these can not be replaced on their own) edit: Si-340t seem to have got crimp separately

I just cut back the wire a bit (in case some wire had got corroded or had resistance issue)

New section length to replace

Pic of the difference in colour between the original wire and new section

New length of wire spliced in and solder up/insulated with heat shrink

New fuse Box fitted and cabled up.

Hopefully this is useful and can save you some expensive repairs.

[snow_muncher]

Excellent guide

[f1_mw]

Wish this thread was around 12 months ago when mine melted! Still, local autoelectrician sorted it for £50 so wasn't too bad.

[Bowders1]

Wish this thread was around 12 months ago when mine melted! Still, local autoelectrician sorted it for £50 so wasn't too bad.

Always the way isn't it...

[petecook859]

Thanks to you all for your very useful advise.I got my "as new" fuse box from Roadside Rescue Poole Dorset.Excellent firm.They do all Skodas Website www.skospares.com Email:[email protected]

[Tech1e]

It isn't that difficult or expensive to buy the loom and replace the whole length. The alternator loom is seperate.

[Bowders1]

It isn't that difficult or expensive to buy the loom and replace the whole length. The alternator loom is seperate.

Very true Tech1e , and it is also not that difficult fixing the current cable and even less expensive...

Always options....

[VWD]

If you're going to the trouble of replacing a length of cable & soldering in a joint - what's to stop you first of all if it's only a HR crimp ,from cleaning out any crud ,applying rosin flux to the crimp ( to clean out any oxidation) ,and soldering the crimp to the wires - At least IMHO worth a try first . Or are there any reasons ( apart from needing a LARGE iron ) not to give this a try first ? .Even then ,a small flame directed at the tip of the crimp should give enough heat to let flux do it's job,and melt solder .As an after thought -I might suggest using plumbing solder -needs a bit more heat, as it

1) needs more heat to undoe the jount

2) can be more solid than electronic solder .

Edited 29 January, 2012 by VWD

[Tech1e]

More so on the TDi but I have seen on the petrols to the joint actually corrodes at the alternator end to, the problem isn't always at the battery end.

[Bowders1]

If you're going to the trouble of replacing a length of cable & soldering in a joint - what's to stop you first of all if it's only a HR crimp ,from cleaning out any crud ,applying rosin flux to the crimp ( to clean out any oxidation) ,and soldering the crimp to the wires - At least IMHO worth a try first . Or are there any reasons ( apart from needing a LARGE iron ) not to give this a try first ? .Even then ,a small flame directed at the tip of the crimp should give enough heat to let flux do it's job,and melt solder .As an after thought -I might suggest using plumbing solder -needs a bit more heat, as it

1) needs more heat to undoe the jount

2) can be more solid than electronic solder .

A quick answer is nothing at all

I just did would i could with the parts and solder I had at the time. Either way would work.

It was not that much trouble. There are many ways to skin a cat.

[bobbins666]

Just had mine go a couple of hours ago,comin' down the motorway in the pouring rain then radio went off,couple of warning lights came on,dash lights went dim then no indicators or wipers,bloody great.Managed to coax it off the motorway after pulling over a couple of times to wipe windscreen(fortunately was only bout 1/4 mile from exit.Called AA and he cut cable back and fitted new crimp and connectors.Jobs a good un.Just got to buy a new fuse box now as its melted well and truly.Certainly something to check as a precaution for skoda owners coz i had absolutely no warning at all.

[Elts]

What size of crimp is needed for this?

[toastie]

hi , i think the answer to my problems in here but im not quit getting it . 

 

my battery light came on and then had a flat battery 

 

jump started it a couple of times and then drove it about 2 miles to a mates place . 

 

found the melted fuse and by passed it buy sticking the black wire strait to the battery terminal (this seemed a quick esy way to test it but now im not so sure) , it worked fine and but then got i bit of smoke and the black wire got very hot . 

 

then went and got the proper fuse and put it all back thinking it will still work and if it gets hot it will blow the new fuse with no harm done .

 

but now it wont turn over , trys a tiny bit like a flat battery buy no where near starting even with jump leads or starter pack .

 

any ideas would be very welcome , have i buggered something else up ? cheers d 

[Bowders1]

hi , i think the answer to my problems in here but im not quit getting it . 

 

my battery light came on and then had a flat battery 

 

jump started it a couple of times and then drove it about 2 miles to a mates place . 

 

found the melted fuse and by passed it buy sticking the black wire strait to the battery terminal (this seemed a quick esy way to test it but now im not so sure) , it worked fine and but then got i bit of smoke and the black wire got very hot . 

 

then went and got the proper fuse and put it all back thinking it will still work and if it gets hot it will blow the new fuse with no harm done .

 

but now it wont turn over , trys a tiny bit like a flat battery buy no where near starting even with jump leads or starter pack .

 

any ideas would be very welcome , have i buggered something else up ? cheers d 

 

What you have done is not a bright idea buddy.

 

And yes is very linked to the issue in this thread.

 

The fuse gets hot coz the wire is not running current freely to the terminals, so you remove fuse and then pass a bad cable direct to the battery that the cable has a suspect current flow.probably due to either the cable crimp end can not let the alternator amps (110A) flow to the battery and so what happens is that current energy is stuck at the end of the cable making it get hotter and hotter.  That is what the fuse is telling you each time it pop's.

 

This is what i posted up above

 

"As the alternator is drawing 110A through the battery and loose connection will start the resistance issue. Once you have that issue it is hard to eradicate without fully changing the alternator lead"

 

So you go and place a suspect cable direct to the battery that smoked and has probably fried the battery (you maybe lucky). Then after the to try to just put another fuse back in. You are lucky you did not get a fire as that is common.

 

Do not drive car until fixed properly 

 

I replaced the crimp end of my cable when it start and caught it in time. But if you have not then a new black alternator cable is required at around £40.

 

When engine was running If you touched the battery fuse box and you feel hot cable ends this is a sure sign you are getting build up of resistance.

 

Get that cable fixed and or replaced and maybe you will need another battery but you can get that checked for current flow 

[toastie]

hi , i only by past for a a few second wile checking it , still not a great idea but no intention to drive it and on hand to turn it strait off ,. 

 

i got a new second hand wire today from the scrappy and its all up and working with fuse  

 

there is still some heat . i also check 2 other vw's with the same set up and they both had some heat . im going to uprate the hole set up as don't want it happening again but should i expect to eliminate the heat all together ? 

 

as for the battery its band new so i hope iv not baked it , it seems ok so far but we will see . 

 

Thanks loads to everyone on this thread , its amazing what you can learn on here in half hour after spending all day not getting anywhere and swearing  

[toastie]

also what amp wire am i looking for to uprate it ? any ideas ? cheers d

[kentphil1]

The need to upgrade is not so much the cable, but more in ensuring a good quality connection on both ends of the cable. there are plenty of quality large cable crimping tools available such as this - http://www.ebay.co.uk/itm/261342731142?_trksid=p2055119.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT, or if you don't want to invest that heavily, take your cable to a good auto electrician, and ask him to do the cable ends for you.

 

It is still possible that the latest used cable that you now have is not that much better than the one that has just failed due to the same problem of resistance at the connectors, and hence you still have some heat.

 

Hope it helps

[toastie]

cheers for tip .. im surprised someone's not making a uprated one as its so common . its the first thing id look at when buying again , ta d  

[toastie]

do we know what amp the cable in there at the moment is ? ta d 

[Bowders1]

The need to upgrade is not so much the cable, but more in ensuring a good quality connection on both ends of the cable. there are plenty of quality large cable crimping tools available such as this - http://www.ebay.co.uk/itm/261342731142?_trksid=p2055119.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT, or if you don't want to invest that heavily, take your cable to a good auto electrician, and ask him to do the cable ends for you.

It is still possible that the latest used cable that you now have is not that much better than the one that has just failed due to the same problem of resistance at the connectors, and hence you still have some heat.

Hope it helps

+1 on this.

As these cars are getting on a bit likelihood is used cables could build up some resistance at cable ends as you state due to poor connection/crimps and again even if a crimp is tight and looks good once it has been exposed to the conditions will get progressively worse.

[kentphil1]

+1 on this.

As these cars are getting on a bit likelihood is used cables could build up some resistance at cable ends as you state due to poor connection/crimps and again even if a crimp is tight and looks good once it has been exposed to the conditions will get progressively worse.

Yep, should have made it clearer that I meant refluxing and fitting new ends to the cable rather than re-crimping the old ones - recipe for hidden failure otherwise

[toastie]

cheers , im going to put a hole new wire in fir sure , just trying to assemble the parts . thanks for all the advice d

[toastie]

just occurred to me that there 4 ish other wires going to the other fusees in that box , i thinker red one , would any of them do as a good replacement ? cheers d 

[mattvrs1]

Iv just had to do mine replaced the loom as £40 odd quid from tps it also connects to fan and air con worth checking the earth under battery try as mine was green

[vigyaz]

If you are intending on cleaning up your connections definately grab some electrical cleaning solvent first, makes life alot easier!

Also. a good way of protecting the terminals from corrosion is vaseline believe it or not lol, my old man said it was common practise at the ford garage he worked at many years ago .

 

 

Also note:

 

in regards to the factory crimps being poor, if a crimp is correctly secured onto a cable it creates what is known as a 'cold weld' and is supposed to stop ingress + corrosion. so i would reccomend as stated above earlier in the post that if unsure just to whip the connections off + heat the ends up with a soldering iron + apply some solder, it will not only assist with a good electrical connection but also seal the crimp from oxidisation.

hope this helps!