Changed Alternator !! Now got probs...can you help?

[chillihotrodders]

Hi - I'm sure I'm not the first or will be the last but need some help on an alternator swap.

 

I had and LRA 100 (old lucas) alternator on my boat engine (late 70's Cortina 1600cc), which was old and not pulling its weight. I have sourced an LRA 101 which I was told would do the job. However on the new unit there is a wire missing !!. On the old 100 unit there was a green wire which was a perminant fixture and came out of the alternator's housing, this connected onto a connector and disappeared into the wiring loom (not sure if it was an earth or someting to do with the charging light). The other spade connectors seemed to be the same (2 wide and 1 narrow).

 

I have now installed the 101 and althought he engine starts I'm not convinced it is performing. The problems I am experiencing are;

 

- The charge light on the dash is now constantly out.

- I have not connected the green wire as there wasn't one!

- I have a test device to put across the battery and the charge is not higher than when the engine is not running.

 

Can anyone off up any help?

Thanks

[chris w]

Hi - I'm sure I'm not the first or will be the last but need some help on an alternator swap.

 

I had and LRA 100 (old lucas) alternator on my boat engine (late 70's Cortina 1600cc), which was old and not pulling its weight. I have sourced an LRA 101 which I was told would do the job. However on the new unit there is a wire missing !!. On the old 100 unit there was a green wire which was a perminant fixture and came out of the alternator's housing, this connected onto a connector and disappeared into the wiring loom (not sure if it was an earth or someting to do with the charging light). The other spade connectors seemed to be the same (2 wide and 1 narrow).

 

I have now installed the 101 and althought he engine starts I'm not convinced it is performing. The problems I am experiencing are;

 

- The charge light on the dash is now constantly out.

- I have not connected the green wire as there wasn't one!

- I have a test device to put across the battery and the charge is not higher than when the engine is not running.

 

Can anyone off up any help?

Thanks

 

There will be a thick wire connected to a terminal (usually) marked B+. This conects to the battery positive.

 

There will be a thin wire which connects from a terminal (usually) marked D+ which connects to the charge light. (There are other letter designations used for this wire which Snibble will know).

 

There will be an earth connection (thickish wire) from the frame of the alternator to the battery negative.

 

There may be a connection marked W that goes to the tacho (There are other letter designations used for this wire which Snibble will know).

 

The wire that comes out of the innards of your original alternator is probably a connection to the field brush (the wire is called the "field wire") and is intended to connect to an external alternator controller. Do you know whether you have an external controller?

 

However, if the charge light is permanently out, then that last wire may be the charge light wire (the one normally designated D+ as described above).

 

Can you post (clear) photos of the two alternators?

 

Chris

 

I'm not familiar with the actual alternator, but all alternators have common features.

[RobinJ]

I had and LRA 100 (old lucas) alternator on my boat engine (late 70's Cortina 1600cc), which was old and not pulling its weight. I have sourced an LRA 101 which I was told would do the job. However on the new unit there is a wire missing !!. On the old 100 unit there was a green wire which was a perminant fixture and came out of the alternator's housing, this connected onto a connector and disappeared into the wiring loom (not sure if it was an earth or someting to do with the charging light). The other spade connectors seemed to be the same (2 wide and 1 narrow).

 

I have now installed the 101 and althought he engine starts I'm not convinced it is performing. The problems I am experiencing are;

- The charge light on the dash is now constantly out.

- I have not connected the green wire as there wasn't one!

- I have a test device to put across the battery and the charge is not higher than when the engine is not running.

The LRA 100 had three connections, a stud terminal for the B+, a blade connection for the warning lamp and an integral wire for the phase tap (tacho) connection. The LRA 101 should be almost identical as its part of the same family.

- Sounds like the warning lamp is connected or pssibly open circuit.

- Do you have an rpm meter (not working) or does this do something else?

- You need a pretty accurate voltmater to check the voltage is going up from ~12V to 14.2V, but suspect its the B+ terminal may be connected wrong?

[Sir Nibble]

???

First, LRA100 and LRA101 are part numbers for Lucas exchange units, the alternators concerned are both 34A ACR units and the only difference between them is that the 100 is RH fixing and the 101 LH, ( it's a 2 minute job to swap them from LH to RH or vice versa). My first thought was that your homeless cable is a battery sense lead, but I have the lucas catalogue in front of me and both have only the connections Chris describes above.

There is nothing whatever to be gained in getting this unit working as both have the same dismally poor 34A output, (though many later units, as old core became more difficult to source were 45A). You would probably be well advised to try and get hold of an LRA 463 which has identical terminals and a 65A output. Meanwhile, put the old unit back.

[chillihotrodders]

Thanks all for the feedback, I have tried to post a picture of the old LRA100 but having upload problems. I have found out that I have a Kestrel 90 alternator controller and this "field" wire might be someting to do with it !! The new 101 dosnt have this and could be the problems to the light and charging (any one know if this is the case??),

Can I adapt the new one to host this wire , with some soldering etc...?

 

So not now sure on my next best steps....

 

Put the old knackered one back?

Adapt this new one?

or spend £100 on a different one?

 

Best advice please, but for the time being would like to utilise the new one.......

 

Thanks for your help

Simon

[Sir Nibble]

Thanks all for the feedback, I have tried to post a picture of the old LRA100 but having upload problems. I have found out that I have a Kestrel 90 alternator controller and this "field" wire might be someting to do with it !! The new 101 dosnt have this and could be the problems to the light and charging (any one know if this is the case??),

Can I adapt the new one to host this wire , with some soldering etc...?

 

So not now sure on my next best steps....

 

Put the old knackered one back?

Adapt this new one?

or spend £100 on a different one?

 

Best advice please, but for the time being would like to utilise the new one.......

 

Thanks for your help

Simon

Take out the two 1/4 hex screws and remove the black plastic cover, reconnect and get back to say "Done that" and I will talk you through a few checks and tests.

[chillihotrodders]

Take out the two 1/4 hex screws and remove the black plastic cover, reconnect and get back to say "Done that" and I will talk you through a few checks and tests.

 

 

Ok undersatnd that bit, so lets say I'm at that stage as its half hour each way to the boat! when I do this what's next?...........

[PaulG]

I have found out that I have a Kestrel 90 alternator

 

I've got one too. I was wondering who they sold the other one to!

 

You can find the info for this unit here

 

There's a link at the top of that page which takes you to the installation isntructions in Word format.

 

Paul

[Sir Nibble]

OK, firstly, if the warning light doesn't work, nor will the alternator. So, inside the back of the unit identify the regulator, it's a metal box wiv wires coming out screwed to the plastic brush holder. One of those wires should be yellow, with a small test cable, earth that yellow wire. The warning light should come on proving the external circuit. The circuit now is through the brushes into and out of the rotor winding emerging to connect to the metal case of the regulator, using your test lead earth that. The light should come on proving the brush contact and winding continuity. (Sometimes this connection is made via a green wire.) The circuit continues through the regulator's internal circuitry to emerge on a black cable which should have an earth connection. (In the case where the green wire as mentioned obove is present the case of the regulator will be screwed to earth).

 

If your regulator also has red and/or white leads, both of these must be at battery voltage before the regulator will conduct and that will be killed if a split charge diode is present.

 

And that I think is a fistful enough to be going on with.

[chillihotrodders]

I've got one too. I was wondering who they sold the other one to!

 

You can find the info for this unit here

 

There's a link at the top of that page which takes you to the installation isntructions in Word format.

 

Paul

 

Thanks, Just spoke to the MD of Acorn who has ginen a fet tips as the unit isnt working !! Thanks

[Keeping Up]

The alternator should still provide charge when the Acorn unit is not connected

[Sir Nibble]

The alternator should still provide charge when the Acorn unit is not connected

And the warning lamp should still light. Trust me, I'm an official beer hamster.

[chillihotrodders]

Right - opened up the Acorn Unit and it was fried !! so disconnected it. Also replaced the bulb on the dash just in case and Installed the new unit.

 

Seems to be running OK now , however, only getting 13.2V across the battery terminals when running, is this down to the Alternator only being 35 amps? Im a bit concerned still that the batteries are not charging !!

 

Any advice?

[Sir Nibble]

Right - opened up the Acorn Unit and it was fried !! so disconnected it. Also replaced the bulb on the dash just in case and Installed the new unit.

 

Seems to be running OK now , however, only getting 13.2V across the battery terminals when running, is this down to the Alternator only being 35 amps? Im a bit concerned still that the batteries are not charging !!

 

Any advice?

Keep going, with that little alternator, if the battery is discharged it could take a long time for the voltage to come up.

[chris w]

I agree, with that tiny alternator you're only going to get about 18A maximum out of it at typical NB revs.

 

Chris

[RobinJ]

Right - opened up the Acorn Unit and it was fried !! so disconnected it. Also replaced the bulb on the dash just in case and Installed the new unit.

Sounds like an old Kestrel with a push button switch!

If its fried it may have taken out a diode or two, is this the reason why the light isn't working?

Could that stop the internal regulator working properly?

It may be worth having the old unit checked out.

[Joe Bloggs]

Those alternators can run OK at well over 10,000 rpm. In fact when Bosch introduced their "Bosch Compact Alternator" it was OK to spin it up to 18,000 rpm during gear changes. These had forged rotors instead of pressed rotors and the fans are internal. As to alternators with external fans I have a strong dislike of the breed on safety grounds.

 

Years ago I bought a Rover V8, the SD1 type. The battery was the wrong type as it did not have a "toe" to clamp it in place, instead it was roped-down. All was OK until an emergency stop had to be made on a Cornish lane that had narrowed to a one-car-only pinch-point. It seemed that disaster had been averted but three days later the car refused to start. The battery had moved and it had been sawn-open by the V8 powered alternator fan! Acid had been sprayed everywhere and after that the car never stopped rusting.

 

As to alternators with strange terminals, watch out for the "W" terminal which is AC. On diesel vehicles the "W" terminal drives the tacho. Sometimes the "W" terminal is used on petrol vehicles to heat an element in an electric choke so a Ford Cortina could possibly have a "W" equipped alternator.

 

Watch out for the rusty-bolt-effect where manufacturers use fortuitous connections as an earth, For example I used to run a Ford Granda which had extremely poor charging even after the alternator and battery had been changed, It turned out to be an electrically burnt cylinder block and alternator mounting bracket as rusted cast iron does not make a good connection. There were about a dozen fortuitous connections between alternator B- and battery B- but simply fitting an earth braid transformed the car! 70 amps needs good connections!

 

Extremely good internal fan alternators can be obtained from scrap Land Rover Discoveries and petrol Rover 800s. As to Bosch alternators the build-plate or label usually has two current ratings. The lower figure is the output when the alternator is being turned at 1500 rpm.

 

Virtually all alternators rely on current through the ignition warning light to start-up the charging process. Good luck!

[WotEver]

I suspect that after well over 8 years his alternator problems are now sorted.

[FORTUNATA]

Be careful in assuming the alternator isn't charging. It may be charging but not at optimum level. I fitted a Lucas recently and found it wasn't charging so well. It seems the belt needs to be swapped to get a better drive. The dummy lamp had to be reved a bit to get it to go out. The D+ lamp wire is the smaller connecter but make sure you have total contact of the spades to clean terminals. The D+ goes to battery pos and, on engine start, polarity between those 2 points equalises. So, no light. The B+ must never be disconnected during charge. Anyway on my Lucas I found a gradual increase in terminal voltage and I got a 12.7 reading after the engine had been running a while in idle. However the drive needs tightening. I was also annoyed over the hellish job I had removing the original alternator as I had little access to one lug. And on opening that unit it was caked in decades of grime.

[RLWP]

I suspect that after well over 8 years his alternator problems are now sorted.

 

Or he has adapted well to living by daylight

 

Richard

[Theo]

I see that Chris W replied but not Gibbo. This must be quite and unusual electrical topic for that to happen (or not happen, I suppose)

[WotEver]

I see that Chris W replied but not Gibbo. This must be quite and unusual electrical topic for that to happen (or not happen, I suppose)

Well, it was a Snib job really and he sorted it after a very few posts. No need for Gibbo to put his pint down lol

[Theo]

Well, it was a Snib job really and he sorted it after a very few posts. No need for Gibbo to put his pint down lol

Wel, yes, you are right.

 

Mr Snibble gave me some very useful alternator advice when I was newly on the Grand Tour in 2008.

 

N

I've got one too. I was wondering who they sold the other one to!

 

You can find the info for this unit here

 

There's a link at the top of that page which takes you to the installation isntructions in Word format.

 

Paul

They sold it to the chap who had my boat before me. It was a right old battery boiler. I got rid of it when my inverter started cutting out due to aver voltage. It was delivering getting on for 16V IIRC.