28 replies to this topic

[matty...]

Ah right that means that both terminals are ground. so you light should light up when connected. My light is very dim which could explain the 4.? Ohms reading.

In this link the top wiring diagram it shows the wiring. Ive wired mine so the ignition light is on the switched ignition as after all this is what it is.

http://www.westfield...alternator.html

Its going to be the weekend before I get to try it though. This is how I had my Matiz alternator wired though.

[Udo]

Ah right that means that both terminals are ground. so you light should light up when connected. My light is very dim which could explain the 4.? Ohms reading.

In this link the top wiring diagram it shows the wiring. Ive wired mine so the ignition light is on the switched ignition as after all this is what it is.

http://www.westfield...alternator.html

Its going to be the weekend before I get to try it though. This is how I had my Matiz alternator wired though.

Yeah should light up being the word for it! if I earth the wire it lights up and its an earth from the main post so it should light up but doesn't.

Thanks for your help matty, I'm going to try again in the morning when I'm less annoyed with it but pretty sure I've already tried how its wired in that link.

Looks like my deadline has gone now, if I cant get it sorted tomorrow it means no MOT friday morning and so no show at Lincoln Mini show Sunday.

Also going to look at my crimped terminals but have a proper crimping tool and never had a problem before but you never know

Edited by Udo, 16 April 2008 - 09:19 PM.

[matty...]

Hmmm???

You could still get it MOT'd without an alternator, if its not too far away? Your running a leccy water pump so just take the belt off and drive it on the battery?

I would connect it how I said then try and start it and see what voltage you get when its running!

[Udo]

Its to far to drive on battery take it to a nice small garage whos owner used to race minis so is shall we say understanding of things.

I'll fit the header tank tomorrow & connect wiring as per that link above and try and start it and see what happens.

[matty...]

Its to far to drive on battery take it to a nice small garage whos owner used to race minis so is shall we say understanding of things.

Could you trailor/tow it there, you'd only need to start it for emmissions then?

'll fit the header tank tomorrow & connect wiring as per that link above and try and start it and see what happens.

I'd try this first. Have you had it running yet at all?

[Paul Wiginton]

Cheers paul but thats where I got the info on wiring which doesn't seem to be working

It couldnt be simpler

Paul

[Udo]

Cheers paul but thats where I got the info on wiring which doesn't seem to be working

It couldnt be simpler

Paul

Thats what I thought but it dont seem to want to work

Matty no not had it running yet as didn't have a header tank till yesterday

No trailer or even car with tow hitch but I dont need to worry about emissions as long as it dont smoke

[Udo]

Its to far to drive on battery take it to a nice small garage whos owner used to race minis so is shall we say understanding of things.

I'll fit the header tank tomorrow & connect wiring as per that link above and try and start it and see what happens.

What happened was nothing! engine turns over ect but wont fire - alternater wired as per the westfield link by the way

[GraemeC]

Well the alternator shouldn't stop the engine firing. I expect you've done the usual checks - spark, fuel etc?

[Udo]

yeah done the checks, have both fuel and spark but still not even a hint of it firing

So now have 2 issues why even thou there is fuel and spark wont it fire and the alt

[matty...]

yeah done the checks, have both fuel and spark but still not even a hint of it firing

So now have 2 issues why even thou there is fuel and spark wont it fire and the alt

Join the club..welcome to the 16V world!

Sitck to it mate you'll get there!

[stevemkeen]

Interested in this post, fitting one of these alternator, can someone confirm if there should be a near short to ground on the Ignition terminal of a desco alternator, I get 4.7Kohms when i checked it , if this is the case does this suggest

I have a problem with the alternator I'm fitting, open circuit components etc, or do I need to wire the ignition light differently, any help would be appreciated.

[ibrooks]

Might have been better to start a new thread rather than resurrect one 7 years old but hopefully this file might clear some things up as regards what connection is what.

 

Now for how to connect them to a Mini's wiring.....

 

First you need to understand that a car's power system is rarely at exactly 12v. The battery will supply whatever it can depending on it's state of charge - that's usually around 12v on a charged battery. Once the alternator is supplying power it does it at more than 12v - it has to in order to "force" power into the battery over the 12v the battery is making. Imagine the battery is a tank of water with a pipe coming out of the bottom to the ground. How high that tank is off the ground represents the voltage. Now the alternator is another tank connected to that pipe - if it's lower than the battery then it'll fill up as the battery drains but if it's higher then water will flow from it into the battery. There's some basic electronics in the alternator to prevent it from forcing so much into the battery tank that it overflows.

 

OK - egg sucking lesson over (maybe).

 

The Ignition lamp on a Mini works by getting battery voltage from the ignition switch to one side of the bulb. The other side of the bub goes to the lamp connection on the alternator which is grounded when the alternator is making less than battery voltage and goes to battery voltage when the alternator is making more. Once both sides of that bulb are at battery voltage no current flows so it goes out. This is the wire that originally went to the small spade on the Mini's alternator. It's the L terminal on the diagram.

 

The coils on an alternator need to be "excited" to work. On many alternators this is done internally but on some it needs an input. If it's permanent then the battery can be drained by the alternator when the car isn't running so it needs to be switched. The Mini doesn't have this wire as standard so you'll need to add it. It's the IG terminal on the diagram.

 

Battery sense - generally an idiot proofing mode to prevent the alternator from generating current if the battery is removed whilst the engine is running as that's not good for the regulators. Some have it (labelled S), some don't and some have the terminal but don't use it ( labelled D). Again the Mini doesn't have a specific wire so add one and for the purposes of the Mini wiring a short wire to the output post of the alternator will do fine as that's permanently connected to the battery +ve terminal so long as the rest of the wiring hasn't been messed with - this won't give you the designed protection but without the maxi-relays and mega fuses on the cars these were designed for it would be hard to incorporate this anyway so just live with it and don't pull the battery connections with the engine running the same as a standard Mini and alternator.

 

Iain

Attached Files

•  alternator_connections_002.gif   45.07K   19 downloads

Edited by ibrooks, 24 July 2015 - 08:21 AM.

[KernowCooper]

@ibrooks Battery sense - generally an idiot proofing mode to prevent the alternator from generating current if the battery is removed whilst the engine is running as that's not good for the regulators

 

Not what the Alternator sense cable does I'm afraid, if the battery was to be disconnected from the circuit with the alternator on charge, the Alternator voltage would spike into the hundreds of volts and the diodes being around 32v would pop, hense no diode pack working.

 

The phase wire on the Alternator is there to ensures that the regulator, inside the alternator, monitors the voltage at the battery and continually adjusts to keep it constant. If the sense wire is connected to the alternator B+ terminal, the battery voltage will be less than 13.5V because the alternator will not compensate for the voltage drop caused by the resistance of the wires joining the alternator to the battery. Some Alternators don't have a Sense Wire its done internally on the B+ but they are designed this way and are still able to allow the Regulator to see the battery voltage correctly

Edited by KernowCooper, 24 July 2015 - 10:50 AM.