low volts

[what2do]

Irish.david. Your input seems to be on the nail from what I can gather but do you mind if I ask you something (just because I'm a nosy git)? 49 posts in 9 years!!! Where have you been hibernating man???

[bigherb]

Pretty red wire.....but what additional benefit do you think it delivers, your alternator is more than adequately earthed 'connected' to the engine by the solid cast pivot and adjusting bracket....

Martin

I wouldn't always bank on that.

Take one alternator working hard, a voltmeter measuring volt drop across the mounting bracket and an additional earth strap across the mounting bracket.

http://youtu.be/Paq4wRkM9qQ" onclick="window.open(this.href);return false;

Never assume anything.

At least Timwhy knows what he is doing.

[ghost123uk]

I would NEVER have guessed that ^^^ ,

8.5 Amps down that "extra" earth cable Proof of the pudding and all that though. But I don't understand it (and as many on here know, I hate not understanding stuff). The body of the alternator is VERY firmly attached via big bolts and very solid brackets to the main engine casing, so where I wonder is the resistance causing the voltage drop and resultant current drop?

Plus I am seeing there only a .03 of a Volt difference, but ~8.5 Amps

[bigherb]

so where I wonder is the resistance causing the voltage drop and resultant current drop?

Electrolytic corrosion between the steel and alloys.

Plus I am seeing there only a .03 of a Volt difference, but ~8.5 Amps

Enough to hive of 8A the other odd 30A is still going through the mounting bracket.

[irish.david]

I think that the explanation for the 8.5A is simpler than you might expect although it’s impossible to be sure without seeing other readings.

You’re not getting an extra 8.5A using the additional earth cable, rather the 10 Amps (i’ve guessed at this figure) that was originally flowing entirely through the engine block has now split itself between 8.5A on the wire with the lower resistance, and 1.5 through the block with the higher resistance (more guessed figures, but you get the idea). If you’re really wanted to see if any extra current was produced by introducing the earth wire you’d need to measure the current output of the alternator on the positive wire and compared it with and without the extra earthing wire connected. Because of the multiple return paths on the earthed side, the only true way to measure alternator output is on the positive wire.

A true test to see how much of an advantage the extra wire would be would be to repeat the test but measure the current output of the alternator on the positive wire and try it without the additional wire connected, with it connected on top of the gearbox and then with it connected to a good earth point somewhere on the chassis. I’m sure that the biggest improvement that you’d see was when the wire was connected to the chassis ground as that’s the same thing that the battery and most of the other equipment is grounded to. Another thing that would help you get better readings would be to switch on as much electrical equipment as possible (lights, heater etc) as the more current that flows in a circuit the more pronounced voltage drops due to bad connections and old cable are going to be.

If you do see a noticeable difference in the current readings when you connect the extra wire to the top of the gearbox then all you need to do to fix that is remove a few of the bolts that hold the alternator bracket on and polish up all the contact metal surfaces and refit. Do the same with the gearbox bolts by loosening one and giving the metal surfaces a quick polish and then i’m sure when you check again the problem will have almost vanished. As bigherb said, you get all sorts of corrosion between metal surfaces which increase electrical resistance but a lot of time you can fix them just by loosening and then retightening a bolt or two as that breaks through the thin layer of corrosion between the metal.

In the youtube clip the wire only made 0.03v of difference which is really not a lot to worry about, although i’ll admit that this would rise when the electrical load increased. To put this in context, if you had a reading of 13.5v on the battery before the additional wire, then adding the wire would give you 13.53v on your battery, which isn’t going to make a huge difference.

I’m not trying to say that anyone doesn’t know what they’re doing and extra earthing is always a good thing, but the charging system has a few weak points and the best way to improve it is to target those first.

Dave

@what2d

I first got my van about 9 nine years ago shortly before starting a career working at sea. For the next 8 years i spent most of my time on ships or travelling and not too much at home so the van was put into storage and i only occasionally did the odd job on it. Last year i started building ships instead of working on them and will hopefully be spending a bit more time at home so i’ve got the van down in the south of Ireland at a place called Krazy Kombis for a full, back to bare metal and complete running gear overhaul, type refurbishment. Cause i’m now planning a few nice electrical upgrades and other bits and pieces i’m back on the forums a bit more.

[what2do]

Looking forward to your input in the future. Good luck with your ventures/follies, etc.

[California Dreamin]

so where I wonder is the resistance causing the voltage drop and resultant current drop?

Electrolytic corrosion between the steel and alloys.

Plus I am seeing there only a .03 of a Volt difference, but ~8.5 Amps

Enough to hive of 8A the other odd 30A is still going through the mounting bracket.

I certainly don't dispute that bad earthing on the alternator can cause issues......problems like this are common on alternators with 'metalastic' type mounts but these are nearly always fitted with a short (10cm or so) braided earth looped cable between the alternator body and engine.
I can't really comment on the video other than to agree that there is definitely an earthing issue, however, a solid clean pivot securely bolted, together with the substantial adjustable mounting bar (again, clean and tightly bolted to the engine) gives a more than sufficient earth for a meagre 45 - 65amp alternator.
I can't help but think that the 'cure' in this case would have been to clean up the existing earthing points although 'bolt and braces' approach would be to add a short braided cable between the alternator and engine...as Volkswagen did on many other models.
Adding 'extra' earthing cables definitely can't hurt but in some cases are just a mask to the actual fault.
Incidental...I do have an extra earth strap on my own van between one of the starter mounting bolts and OS chassis leg.

Martin

[bigherb]

a solid clean pivot securely bolted, together with the substantial adjustable mounting bar (again, clean and tightly bolted to the engine) gives a more than sufficient earth for a meagre 45 - 65amp alternator.

Martin

I agree it should be, the point is never assume that it is and it will be forever, always check.

[ghost123uk]

Gosh, there has been some cross contamination on here re "low Volts" and headlight upgrades recently.

The following is from the Headlight Loom Upgrade thread, but is really more at home here The link to the Samba discussion is about a guy who makes Alternator to Starter motor wiring loom upgrades (like Ralph made and discussed ^^^)

My, what a lot of starter and voltage posts this time of year! here's a corker..

http://www.thesamba.com/vw/forum/viewto ... 80424c08c6

Quite heated!

I couldn't be bothered getting to the "heated" bit, but I will say that if that alternator upgrade harness was easily available here in the UK, at a sensible price, I too would likely buy one, same for ready made starter to battery cable. Saves sourcing all the bits and fannying around with cutting HD cable neatly, solder, blow torches and heatshrink etc, all in my cold shed

Hey Ralph, you could make and sell them

When the weather improves I am seriously considering fitting an extra cable, direct from alternator to battery to reduce voltage drop. Not a very elegant solution I know, but very much in the tradition of most owner added wiring on a T25

[Timwhy]

Gosh, there has been some cross contamination on here re "low Volts" and headlight upgrades recently.

The following is from the Headlight Loom Upgrade thread, but is really more at home here The link to the Samba discussion is about a guy who makes Alternator to Starter motor wiring loom upgrades (like Ralph made and discussed ^^^)

My, what a lot of starter and voltage posts this time of year! here's a corker..

http://www.thesamba.com/vw/forum/viewto ... 80424c08c6

Quite heated!

I couldn't be bothered getting to the "heated" bit, but I will say that if that alternator upgrade harness was easily available here in the UK, at a sensible price, I too would likely buy one, same for ready made starter to battery cable. Saves sourcing all the bits and fannying around with cutting HD cable neatly, solder, blow torches and heatshrink etc, all in my cold shed

Hey Ralph, you could make and sell them

When the weather improves I am seriously considering fitting an extra cable, direct from alternator to battery to reduce voltage drop. Not a very elegant solution I know, but very much in the tradition of most owner added wiring on a T25

The heated bit is from one guy that wants to be a vendor but seems he doesn't want to manufacture anything. He posts on threads that are related to Jays' product and just tries at every turn to dis-credit him.

[Smosh]

So a few photos to go with these posts.

Gearbox to chassis earth: to be replaced (signs of green within cable that arent clear in photo.


connector to back of alternator:


Guess some cables need redoing...




can i just cut back cables and solder on to a new terminal, or, should I replace the cables... if so, anyone fancy doing that for me? Might be a lesson for the wife routing those cables,

[Timwhy]

Looking at those wires, I'd say you found the cause of your voltage loss.

They look taped up. I wonder how much corrosion you have down those wires?

What is the alternator model #?

[Smosh]

Haha! Good question... I'll look!

[CovKid]

New cable - for sure. The plug can be replaced with correctly sized spade terminals. Can only refer you back to https://club8090.co.uk/wiki/VW ... ain_cables" onclick="window.open(this.href);return false;

When its that bad all you can do is cut out and renew. No way around it I'm afraid.

Campers/vans this age (with no work done on main cables) are all like this I've found.

You might be able to source new spades for that plug. Unit may even be available on ebay - search for "bosch alternator plug" - saw one listed that may fit. Otherwise you'll have to go for individual ones.

[Oldiebut goodie]

Standard Lucas etc fitment - £4.50 http://www.ebay.co.uk/itm/3-PIN-WIRING- ... 3a86ab4a31