Jump to content

Alternator info


Featured Posts

My knowledge of auto electrics is minimal , and I've forgotten most of that. The charging light wouldn't go off today and it seems to be a loose connection on the plug that goes into the back of the alternator, held in by a spring clip. When I gave it a shove, all became well. 

Is this likely to be the case, or is it something else and that was just coincidence? 

Link to comment
Share on other sites

8 minutes ago, Arthur Marshall said:

My knowledge of auto electrics is minimal , and I've forgotten most of that. The charging light wouldn't go off today and it seems to be a loose connection on the plug that goes into the back of the alternator, held in by a spring clip. When I gave it a shove, all became well. 

Is this likely to be the case, or is it something else and that was just coincidence? 

That would be an old Lucas ACR alternator. Isolate or disconnect battery first to be on the safe side. Ping the wire clip clear and wriggle the plug out. There should be two large spade connectors and one small, clean em all up the male ones on the alternator too with fine grit paper, and squeese the female connectors on the ends of the cables very very slightlty and very gently with pliers to get a better contact. Push the plug back on , secure with clip and switch back on.

Edited by bizzard
Link to comment
Share on other sites

Did the light remain at full brilliance? Do you have a split charge relay fitted? The light is wired from ignition and gets a return through the alternator so a poor connection will prevent the light coming on rather than keep it on, unless it has an alternative path to negative like a split charge relay.

Link to comment
Share on other sites

I'll clean it all up as per Bizzard. It is all a bit mucky round there.

There is a split charge relay, and the light stayed at full brilliance, apart from a short period when it flickered on and off, then came back on.  After I'd wiggled the plug, the light went out, came back on when the engine stopped and went out when restarted as normal.

I'll replace the alternator when it finally gives up the ghost - I think it was put in by someone from the chandlers in Middlewich.  Mind you, when it does go, RCR will replace it for me, but who knows what with....

Link to comment
Share on other sites

  • 4 weeks later...

Sorry to revisit this. Cleaned it up and working OK, but stopped charging again the other day as spade connector fell out - on examination the thin wire is only connecting by a few strands and the plug is falling apart.  So I have to replace the plug, but due to the way the boat has been rewired (a story i won't go into) the thin wire, which I presume goes to the charging light (the wiring is now untraceable due to the actions required by my last examiner) is too short to strip the rusted end off and re-attach.  Fat wire seems fine.

Question, is it safe just to connect a short piece of wire to the new plug and join it to the original with a connector?

ETA: there are only two wires going into the plug.

Edited by Arthur Marshall
Link to comment
Share on other sites

46 minutes ago, Arthur Marshall said:

Sorry to revisit this. Cleaned it up and working OK, but stopped charging again the other day as spade connector fell out - on examination the thin wire is only connecting by a few strands and the plug is falling apart.  So I have to replace the plug, but due to the way the boat has been rewired (a story i won't go into) the thin wire, which I presume goes to the charging light (the wiring is now untraceable due to the actions required by my last examiner) is too short to strip the rusted end off and re-attach.  Fat wire seems fine.

Question, is it safe just to connect a short piece of wire to the new plug and join it to the original with a connector?

ETA: there are only two wires going into the plug.

You could do away with plasic plug altogether if you want  Just plug the Lucar spade terminals directly onto the male blades on the alternator. I'd crimp or solder new spade terminals onto the wires though. the thin wire can be extended, insulation pared back on both and tightly twisted together and bound with tape or heat shrink tube. I would also cut out of a bit of cardboard  or plastic a little dust shield with slits cut into it to pass around the teminals to cover the terminal aperture on the alternator and glue it on,   Remove the wire clip.

Edited by bizzard
Link to comment
Share on other sites

If the alternator plug is disintegrating, you can buy a new one. https://www.autoelectricsupplies.co.uk/mobile/product/47. This will need crimping, or soldering to the two thick and one thin wire. Alternatively, (see what I did there?), you can just use two 3/8" and one 1/4 inch connector instead of the plug as Bizzard suggests. The thin wire and 1/4 " blade connector is the alternator warning light connection. The two large blades both go to the battery and take the charging current. The reason for using two is that one wouldn't take the large current. More modern alternators tend to use a threaded stud and ring connector for this reason.

 

If you haven't got one, it is a good idea to get a good quality ratchet crimp tool for making electrical connections. Always comes in handy on a boat. To extend the alternator sense wire I wouldn't depend on twisting the ends together and taping over. This will fail over time. A butt crimp connector, or even a chocolate block connector would be better.

 

Jen

Link to comment
Share on other sites

10 hours ago, bizzard said:

You could do away with plasic plug altogether if you want  Just plug the Lucar spade terminals directly onto the male blades on the alternator. I'd crimp or solder new spade terminals onto the wires though. the thin wire can be extended, insulation pared back on both and tightly twisted together and bound with tape or heat shrink tube. I would also cut out of a bit of cardboard  or plastic a little dust shield with slits cut into it to pass around the teminals to cover the terminal aperture on the alternator and glue it on,   Remove the wire clip.

As Jen said above, don’t twist wires together it will oxidise and fail.  A crimp joint using a proper ratchet crimp tool will be sufficiently tight to exclude oxygen for a very long time.  The automotive industry did reasearch and concluded that crimping is best followed by soldering (but the wire around the joint requires support or it will crack (fatigue) over time.  By far the worst method is twisting, which is a failure waiting to happen.

Link to comment
Share on other sites

2 hours ago, Jen-in-Wellies said:

 The two large blades both go to the battery and take the charging current. The reason for using two is that one wouldn't take the large current. More modern alternators tend to use a threaded stud and ring connector for this reason.

 

 

Jen

There's only one wire attached to the large blades - it all seems to work ok.  Would it be more efficient with two, and would they both go to the same place?  The whole shemozzle is annoying as the battery to distributor board has been rewired twice and neither time did the guy doing the work bother to sort this bit out - with the alternator plug just wedged in with a bit of scrumped up gaffa tape.

Link to comment
Share on other sites

Just now, Arthur Marshall said:

There's only one wire attached to the large blades - it all seems to work ok.  Would it be more efficient with two, and would they both go to the same place?  The whole shemozzle is annoying as the battery to distributor board has been rewired twice and neither time did the guy doing the work bother to sort this bit out - with the alternator plug just wedged in with a bit of scrumped up gaffa tape.

That depends upon the maximum alternator output, with an ACR it could be very low indeed. This is why I suggested you save up for an A127.

 

If I was to do this I would strip back more than required so i could split and insulate the strands and also fit two of the large blades. The problem may be caused by the single 9mm connection overheating and loosing its tension on the blade.

Link to comment
Share on other sites

2 minutes ago, bizzard said:

Tightly twisting wires together usually has more contact area than the actual terminal contacts, I'd solder them too, but if not I doubt if they'd fail. .

Something I do do though which most folk don't seem to bother with, is to after baring the wires ready for connecting, especially soldering, is to gently back scrape the wre strands with a sharp knife blade until bright shiny copper, and always before soldering.

Link to comment
Share on other sites

1 minute ago, bizzard said:

Something I do do though which most folk don't seem to bother with, is to after baring the wires ready for connecting, especially soldering, is to gently back scrape the wre strands with a sharp knife blade until bright shiny copper, and always before soldering.

Hey, I do that bizz.

Link to comment
Share on other sites

16 minutes ago, Tony Brooks said:

That depends upon the maximum alternator output, with an ACR it could be very low indeed. This is why I suggested you save up for an A127.

 

If I was to do this I would strip back more than required so i could split and insulate the strands and also fit two of the large blades. The problem may be caused by the single 9mm connection overheating and loosing its tension on the blade.

Or double it up with another main wire from the pos side of the battery or wherever ithe original wire comes from with its own spade connector.

Link to comment
Share on other sites

54 minutes ago, bizzard said:

Or double it up with another main wire from the pos side of the battery or wherever ithe original wire comes from with its own spade connector.

I agree with that but I am not sure how easy the OP will find it to do.

 

Actually, as far as I can tell, the way the ACRs were designed to be used was that one of the large blades connected to the battery while the other fed all the vehicles electrical system so while the engine was running the alternator provided most the car's electrical needs and ding this probably saved the makers a few pence in copper wire size. Not really so sensible for marine use I would suggest where we only tend have warning lamp and instrument loads rather than heaters and headlamps etc.

 

 

Link to comment
Share on other sites

2 hours ago, Tony Brooks said:

I agree with that but I am not sure how easy the OP will find it to do.

 

Actually, as far as I can tell, the way the ACRs were designed to be used was that one of the large blades connected to the battery while the other fed all the vehicles electrical system so while the engine was running the alternator provided most the car's electrical needs and ding this probably saved the makers a few pence in copper wire size. Not really so sensible for marine use I would suggest where we only tend have warning lamp and instrument loads rather than heaters and headlamps etc.

 

 

I do tend to leave well alone.  Considering that the first expert who rewired all this stuff did it so badly (apparently) that I had to have it redone to pass the next inspection (and he was an examiner as well as an experienced boat electrician) I have little faith in my own abilities - they have somewhat diminished anyway over the last thirty years, as has my flexibility in getting into the engine bay. The 2nd para would explain why only one terminal is connected - as far as I can tell, using the headlight takes power direct from the battery rather than the alternator, and there's nothing else used when the engine's running apart maybe from a charger or two.

Link to comment
Share on other sites

4 hours ago, Tony Brooks said:

I agree with that but I am not sure how easy the OP will find it to do.

 

Actually, as far as I can tell, the way the ACRs were designed to be used was that one of the large blades connected to the battery while the other fed all the vehicles electrical system so while the engine was running the alternator provided most the car's electrical needs and ding this probably saved the makers a few pence in copper wire size. Not really so sensible for marine use I would suggest where we only tend have warning lamp and instrument loads rather than heaters and headlamps etc.

 

 

Leyland truck, I think it was the boxer, had the battery connection on the stud terminal and fed the vehicle from the two connectors in the plug making the alternator the main positive junction.

Link to comment
Share on other sites

14 minutes ago, Sir Nibble said:

Leyland truck, I think it was the boxer, had the battery connection on the stud terminal and fed the vehicle from the two connectors in the plug making the alternator the main positive junction.

Just to save a couple of feet of cable?

Link to comment
Share on other sites

1 hour ago, Arthur Marshall said:

I do tend to leave well alone.  Considering that the first expert who rewired all this stuff did it so badly (apparently) that I had to have it redone to pass the next inspection (and he was an examiner as well as an experienced boat electrician) I have little faith in my own abilities - they have somewhat diminished anyway over the last thirty years, as has my flexibility in getting into the engine bay. The 2nd para would explain why only one terminal is connected - as far as I can tell, using the headlight takes power direct from the battery rather than the alternator, and there's nothing else used when the engine's running apart maybe from a charger or two.

 

Not your boat headlight , I was talking about the headlamps and heaters on the cars the alternator was originally designed for and how they were wired. Your alternator could have a maximum out put of about 25 amps and upwards depending upon the model and I think 25A plus through a single 9mm blade is asking for trouble, especially as the female part id so often a rather loose fit after some years. I am tempted to say especially when the unit still has its plastic block connector. I think that if you are going to stay with a single blade I would go with Biz's idea and do away with the block. At least that way you can feel how tight or loose the terminal is on the blade. However please put a neat wrap of insulating tape around the female terminal to ensure it can not easily short out to the alternator case  The proper insulated sleeves for these terminal can     be a bit tight to get into the aperture, especially if all three blades are in use).

 

 

4 minutes ago, WotEver said:

Just to save a couple of feet of cable?

Yes, the manufacturers get up to all sorts of wheezes to save a few 10ths of a penny per vehicle. They are perfectly happy to make crimped three way joints inside harnesses held together with a thin band of brass.

Link to comment
Share on other sites

1 hour ago, WotEver said:

Just to save a couple of feet of cable?

Ford saved millions by going from 1mm cable to 0.75mm for general low current usage. Most likely it was just someone trying to be original. How often do you see systems that have worked well for a century replaced with a system that is so fragile it barely works at all and then only briefly. You don't win a design award for using established technology.

Link to comment
Share on other sites

53 minutes ago, Sir Nibble said:

Ford saved millions by going from 1mm cable to 0.75mm for general low current usage. Most likely it was just someone trying to be original. How often do you see systems that have worked well for a century replaced with a system that is so fragile it barely works at all and then only briefly. You don't win a design award for using established technology.

 

Big companies like Ford have engineers whos primary job is to reduce costs by making little changes like this, its called thrifting. I am aware of one company who paid a lot of money to consultants to have a problem solved and the fix involved adding a small extra component. Some years later this component was "thrifted" away because nobody knew what it did, the original engineers having moved on.  Original problem returned and company engaged the very same consultants to re-solve the very same problem.

 

............Dave

Link to comment
Share on other sites

1 hour ago, dmr said:

 

Big companies like Ford have engineers whos primary job is to reduce costs by making little changes like this, its called thrifting. I am aware of one company who paid a lot of money to consultants to have a problem solved and the fix involved adding a small extra component. Some years later this component was "thrifted" away because nobody knew what it did, the original engineers having moved on.  Original problem returned and company engaged the very same consultants to re-solve the very same problem.

 

............Dave

A mechanic I worked with had a bad day sweating blood trying to get the pedal box out of a metro. One bolt was apparently impossible to get at. At the time I lived with a lady who's brother worked in design for Austin Rover, so over beer I asked him why they couldn't see their way clear to fitting one captive nut. What's one captive nut to the price of a car? His reply, "Quite a lot if you're making quarter of a million a year". Only one possible response, "Oh yea".

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
  • Recently Browsing   0 members

    • No registered users viewing this page.
×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.