Replacement domestic alternator

[SiFi]

My domestic alternator has stopped charging and the duff alternator has no ID, see pics.

 

I'm at a bit of a loss to how I find a direct replacement. Are 'car' alternators interchangeable? I'm hoping to have a self-sensing replacement.

[Tony Brooks]

Find your local starter and alternator specialist and I am sure they will match one up for you.

 

Yours is, as are most, a nine diode alternator, so it will sense from its own output.

 

By and large as long as the bracket dimensions are the same alternates are interchangeable providing you stick with the number f diodes inside, otherwise a degree or wiring is required. That one has an internal fan, but that won't matter unless your engine pulley runs backwards (like the small Lister Sx range).

 

Hopefully someone will be along who can identify the make and model.

[Tracy D'arth]

Send the pictures to Lancashire Rotating Electricals, they will match it and quote you a fair price delivered. I have never been disappointed by them.

 

https://lre-ltd.co.uk/

 

Tracy D'

Just now, Tracy D'arth said:

Send the pictures to Lancashire Rotating Electricals, they will match it and quote you a fair price delivered. I have never been disappointed by them.

 

https://lre-ltd.co.uk/

 

Tracy D'

The connections all need remaking as you are no doubt aware.

[Jen-in-Wellies]

Repair may also be possible at a cheaper price than new. Look for alternator, starter motor repair shops.

[MtB]

4 hours ago, SiFi said:

My domestic alternator has stopped charging and the duff alternator has no ID, see pics.

 

 

Going back a step, this is a bit of an assumption. The absence of charging might not be a duff alternator. Although it probably is!

 

Better to diagnose the fault properly before shelling out on a new alternator. DAMHIK.

 

 

 

 

How do you know it has stopped charging?

 

 

[SiFi]

The measured voltage of the batteries with the engine running or not does not change and charging light I fitted to stays illuminated.

 

I'll take the alternator into Euro Car Parts and see if they can help.

[alan_fincher]

I think I would be wanting to sort out/replace all the cables before assuming the fault is definitely with the alternator.  The state of things where terminations are crimped to iffy looking conductors wouldn't give me any confidence at all.

[Jen-in-Wellies]

34 minutes ago, SiFi said:

The measured voltage of the batteries with the engine running or not does not change and charging light I fitted to stays illuminated.

 

I'll take the alternator into Euro Car Parts and see if they can help.

What charging light did you fit? What was fitted before? If the charging light doesn't allow enough current through (too high a resistance), the alternator won't start charging.

There are plenty of fault finding steps to go through before condemning the alternator. Doing so could save you a lot of money and time overall.

[SiFi]

The lamp was the one that was fitted originally and I have assumed it was a charging LED, i can measure the resistance. The engine alternator seems to charge without an excitation lamp.

[MtB]

9 minutes ago, SiFi said:

The lamp was the one that was fitted originally and I have assumed it was a charging LED, i can measure the resistance. The engine alternator seems to charge without an excitation lamp.

 

It isn't an LED, unless there is something unusual about your charging system.

 

Yes some alternators can self-excite and yours sounds like one. It's still a Good Idea to rule out other causes first though, as spending several hundred quids on an alternator only to find the system behaves exactly the same with the new alternator is beyond annoying. But as a professional fault-tracer these days I find it is well worth trying to spot and rule out all the assumptions one naturally makes when something doesn't work.

 

Its your money however and you might well be right, but I'd be inclined to learn a bit about alternator fault-finding first, so I could be sure. Someone will be along soon I expect who can describe some checks you can do on your system to pin down the fault. 

[Jen-in-Wellies]

53 minutes ago, SiFi said:

The lamp was the one that was fitted originally and I have assumed it was a charging LED, i can measure the resistance. The engine alternator seems to charge without an excitation lamp.

If it is an LED, then it needs a low resistance, high power resistor in parallel to flow enough current for many alternators to charge. More usual is an incandescent bulb, but some of these are too weedy to flow the current needed, or are marginal, working some times, but not others. Don't ask me how I know! Again, if it is an LED, then resistance is a lot more complicated and not so straightforward to measure as it is with a bulb and even with a bulb it isn't entirely straightforward.

Second what @MtB said. Methodical fault finding is generally better than replacing random (expensive) components.

[Tony Brooks]

Of the bulb type warning Lamps it is the C1/2" push in black plastic body ones that are most likely to cause problems because they come in tow identical looking types. Those with a removable metal bulb holds are usually fine, but the ones with just a pair of blades on the back use a grain of wheat dolls house bulb and they rarely work for an alternator - would be fine for a six diode machine though, but the OPs is a 9 diode one.

 

Definitely disconnect the D+ cable and turn the ignition on, the bulb should be off. If it is not then you have a short on the wiring.

[jonathanA]

Looks like a fairly generic A127 type derivitive to me. I have one very similar in my spares box will see if there are any markings on it for you. Here you go it could be a lucas

Obviously its a lucas and not a A127 having a senior moment there.

Edited March 7 by jonathanA
Add pic

[Tony Brooks]

Not an A127 because this one has an internal fan, also no sign of the A127 regulator. The terminal are also wrongly placed for a normal A127.

[SiFi]

Thanks for this, I can see the similarity however I found somebody on ebay who has positively identified it as being a 'Lucas LRA02861'.  I have gone ahead and ordered ... we shall see ... it was not too expensive.

 

I tried local car parts outlets and they can't get this alternator. Apparently it was on the Ford Transit 2001-06 2.3 petrol.

 

https://www.ebay.co.uk/str/rotatingmachinesltd?

[Quattrodave]

Like you've already been told, speak to Lancashire Rotating Electronics.

[nicknorman]

8 hours ago, SiFi said:

The lamp was the one that was fitted originally and I have assumed it was a charging LED, i can measure the resistance. The engine alternator seems to charge without an excitation lamp.

Just to clear up this point there are two types of alternator, a 9 diode machine like the one in your pic. This requires current through the warning light bulb into the D+ terminal to get charging going.

Then there is a 6 diode machine, this does not require a warning lamp to be connected in order for it to work. It is not uncommon for the smaller engine alternator to be the latter type.

[SiFi]

Thank you for this, it is good to know.

[SiFi]

OK I've fitted replacement alternator, connected B+ to leisure battery positive and alternator body to battery negative. I was expecting the battery voltage to appear on the D+ terminal?

Edited April 9 by SiFi

[Tracy D'arth]

10 minutes ago, SiFi said:

OK I've fitted replacement alternator, connected B+ to leisure battery positive and alternator body to battery negative. I was expecting the battery voltage to appear on the D+ terminal?

You need a filament warning lamp from the "ignition" switch to the D+ to excite the (running) alternator, then you will get the voltage on the D+ terminal.

[Tony Brooks]

25 minutes ago, SiFi said:

OK I've fitted replacement alternator, connected B+ to leisure battery positive and alternator body to battery negative. I was expecting the battery voltage to appear on the D+ terminal?

 

Why would it. As Tracy says, D+ is to put electricity INTO the alternator to energise it and cause it to charge. No charge, as with a stationary or unexcited alternator, so nothing on D+.  Just connect the warning lamp wire and I am sure all will work.

 

What was connected to D+ on the old alternator? Be aware that there are a few alternators that use different terminal designations and have a straight ignition feed to wake the alternator p and a few that are self exiting, but if yours has a D+ it is not one of them.

[nicknorman]

3 hours ago, SiFi said:

OK I've fitted replacement alternator, connected B+ to leisure battery positive and alternator body to battery negative. I was expecting the battery voltage to appear on the D+ terminal?

There will only be battery voltage on D+ when the engine is running and alternator is charging. To get the alternator to start charging you would normally have a warning light connected (other end of the warning light to battery + via the ignition switch) and then, with the ignition on but not running, you would get a volt or two on D+, rising to battery voltage after starting the engine.

[Tony Brooks]

31 minutes ago, nicknorman said:

There will only be battery voltage on D+ when the engine is running and alternator is charging. To get the alternator to start charging you would normally have a warning light connected (other end of the warning light to battery + via the ignition switch) and then, with the ignition on but not running, you would get a volt or two on D+, rising to battery voltage after starting the engine.

 

or battery voltage if you took the cable off the alternator and measured the voltage on the CABLE with the ignition turned on.

[SiFi]

15 hours ago, nicknorman said:

There will only be battery voltage on D+ when the engine is running and alternator is charging. To get the alternator to start charging you would normally have a warning light connected (other end of the warning light to battery + via the ignition switch) and then, with the ignition on but not running, you would get a volt or two on D+, rising to battery voltage after starting the engine.

Thanks, I will have another go this morning with the warning light in circuit and engine running 

[Tony Brooks]

1 hour ago, SiFi said:

Thanks, I will have another go this morning with the warning light in circuit and engine running 

 

If it still fails to charge, then may be post a photo of the terminal on the alternator and their designations, just in case you have managed to buy a six diode machine to replace a nine diode one. If you have, you will have to do a bit of extra wiring.