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Topic: Today I'm gonna try and sort my alternator out  (Read 968 times) previous topic - next topic

Today I'm gonna try and sort my alternator out

Good morning, I expect some of you have just gone to bed, today I gonna check my alternator out and use norms  post from a month ago  as my guide, Im not sure whether I need to start a new post or not or carry on with the original post, there are 2 things that I need to sort, firstly the similar problem as norm had even though I found away round it by flicking a spring switch to give power just to exite the alternator I want to get it working correctly as it should, and secondly I need to get my dash warning light working as it should do. when I turn ignition on there usually is a dash light and once alternator starts to charge the light should go out,  firstly I need to do what Brett said and take the lead from the alternator off  the middle terminal of isolator and connect straight to battery terminal , and start it up and see what voltage is coming out, now I have got 2 very small wires just hanging loose near the alternator which could be the wires from the ignition light, one wire is white with a blue stripe and the other is black,  I have found the receipt for the alternator I bought from Riverside alternators and starters and the description on the invoice says alternator  oshkosh truck 55700CX , I have googled it and found it, it's a 130 amp alternator, anyway I'm gonna make a start now, and il try and take a clearer closer photo of everything I'm doing as I go along,  il probably need help especially Brett if your about today,  if I need to carry on norms original post please let me know and il do it that way, I keep scrolling back a month to find it, and try and follow the instructions that Brett and others have put up, thanks kev
1990 foretravel grandvilla, Oshkosh chassis
8.2ltr Detroit turbo

Re: Today I'm gonna try and sort my alternator out

Reply #1

Success for the first stage,  I disconnected middle terminal from alternator and connected to chassis battery terminal on the right, went forward turned ignition on and started it up and the voltage was putting in 14.2 volts then settled at 14 volts on tickover,  so at least now I can disconnect the temporary switch on dash that I used to use to excite the alternator,  before I was only getting 13.2 volts on the dash so definately by bypassing the battery isolater I'm getting alot more charge going into battery's, I'm well pleased,  now the next stage is how do I get my dash warning light to come on when I turn ignition on, and go off once vehicle is running and charging, I ain't gotta a clue which one of these extra terminals on the back of alternator gets connected to the ign dash light,  if you look at the alternator wire from the middle post that I have moved to the chassis battery post, there is a small red wire attached, not sure where it goes but it defo isn't connected to alternator, but so far so good,  il have to go back now and check the schematics, but I must admit I'm not very good at using them, somethings I have found them very useful and can understand them quite well, but there is not alot I seem to understand about the alternator wiring,  I find a volt meter and testing continuity sometimes the better way, anyway I'm going back now to start it up and test all of these extra  terminals on the back to see what I'm getting voltage wise both engine off and running, I can't get a strong enough phone signal where I'm parked to send photos, so I've had to drive a mile up the road on top of a hill to send them  kev
1990 foretravel grandvilla, Oshkosh chassis
8.2ltr Detroit turbo

Re: Today I'm gonna try and sort my alternator out

Reply #2
Oh and another thing, somebody did mention on Nitehawks post that some vehicles will only start charging after you give it 1000 rpm, mine is now like that not a problem cause flicking the switch that I had rigged up was OK but sometimes I would forget to flick it so I would have the engine running for ages and no charge, I'm now going to disconnect the wire that I had rigged up first terminal to the left of b+ as its not needed now but I may be able to utilise that wire now to enable ignition light to come on and then go off once charging, I am now going to get a battery switch which says  battery 1, battery 2  or both, I have one on my boat, that's another good idea that was posted in Nitehawks post,  I'm really getting into this wiring,  any advice on how the ignition dash light is wired to alternator would be a great help thanks kev
1990 foretravel grandvilla, Oshkosh chassis
8.2ltr Detroit turbo

Re: Today I'm gonna try and sort my alternator out

Reply #3
Good morning Kev,

This project will require some sleuthing.  First, to find a manufacturer wiring diagram for your mystery alternator, then to figure out how your charging system is presently configured, and finally to correct any problems.

Searching the alternator "oshkosh truck 55700CX" brings up the link below, which is not very helpful:

OSHKOSH EE34665 ALTERNATOR

Further tracking leads me to:

Wilson HD Rotating Elect 90-04-7020 Alternator + Cross Reference | FinditParts

https://www.oreillyauto.com/detail/c/wilson/wilson-105-amp-alternator-remanufactured/wil0/90047020?srsltid=AfmBOopC3pxp__wjWMMfnx5yTmvTUFH_-jVPR91xgJNQFsJWWiQSYlVT

So far I haven't found a suggested wiring diagram.  Got to go to a doctor appointment now.  I'll keep looking later today.  Cheers.
1993 U280 SE 40' WTBI, Build: 4359
C8.3 300hp, 6-Speed, Exhaust Brake
960 watts on the roof (6 x 160)
Sorento (or BOLT) on a Kar Kaddy SS
"Nature abhors a vacuum"

Re: Today I'm gonna try and sort my alternator out

Reply #4
Good morning Kev,

This project will require some sleuthing.  First, to find a manufacturer wiring diagram for your mystery alternator, then to figure out how your charging system is presently configured, and finally to correct any problems.

Searching the alternator "oshkosh truck 55700CX" brings up the link below, which is not very helpful:

OSHKOSH EE34665 ALTERNATOR

Further tracking leads me to:

Wilson HD Rotating Elect 90-04-7020 Alternator + Cross Reference | FinditParts

https://www.oreillyauto.com/detail/c/wilson/wilson-105-amp-alternator-remanufactured/wil0/90047020?srsltid=AfmBOopC3pxp__wjWMMfnx5yTmvTUFH_-jVPR91xgJNQFsJWWiQSYlVT

So far I haven't found a suggested wiring diagram.  Got to go to a doctor appointment now.  I'll keep looking later today.  Cheers.
Thanks chuck, mutch appreciated, meanwhile, I have been doing a bit of testing myself, the wire that I have attached to the alternator direct from the dash on a spring switch that I used to use to excite the alternator I've left it on that terminal for now on the back of alternator and I've just done an interesting test, I've removed the temporary spring return  switch under front dash and I've connected a volt meter, so I now have one wire hot when ignition on and the other coming from the alternator and when I turn ignition on I'm getting a reading of 12. 8 volts so that wire now that is attached to the left of b+ is now a ground wire which is giving me the voltage, I then started the engine gave it a little rev to just over a 1000 rpm alternator was putting out the charge and the volt meter went down to 6. 2 volts, so I thought OK I have a hot wire and a ground wire, il try it with a bulb connected between these 2 wires and do the same test, now because the volt meter showed up 12.8 volts I was pretty confident that the bulb may light up and go out when I started the engine, but that didn't happen, that's confused me a bit now cause if the volt meter is showing voltage then why wouldn't it light the bulb, anyway it doesn't work as I expected it to so  later on after I've been into town, I'm going to move that wire off that terminal on the alternator and do the same test again on the terminal to the left of that one and see what happens, try it on everyone 1 x 1. I read an article this morning and il try and copy and paste the link but that is doubtfull, what it actually says in brief that the warning light on the dash is wired 1 side to ignition hot and the other to the self excite terminal, apparently when you turn ignition on this wire is a ground wire but when the engine starts and charge goes through, it then becomes hot and equalises with the voltage coming from the other side of bulb from hot ignition on and the bulb is supposed to go out, so I've had enough now need a break, il let you know how I progress later on,  thanks kev
1990 foretravel grandvilla, Oshkosh chassis
8.2ltr Detroit turbo

Re: Today I'm gonna try and sort my alternator out

Reply #5
Check the bulb to make sure it is good?
1993 U280 SE 40' WTBI, Build: 4359
C8.3 300hp, 6-Speed, Exhaust Brake
960 watts on the roof (6 x 160)
Sorento (or BOLT) on a Kar Kaddy SS
"Nature abhors a vacuum"

Re: Today I'm gonna try and sort my alternator out

Reply #6
Yeah I did that, I tried 2 or 3 different bulbs, was so weird cause volt meter showed voltage, couldn't understand why when alternator was charging it only went down to 6 volts, I would have expected it to drop to zero, I will check the bulbs later before I do go any further, I mean what are the chances of 3 bulbs all not working, they come out of there new box, I tested first with a 21 watt bulb then I thought perhaps it was too high watts so I then put a couple of 5 watt bulbs still nothing, it's very unusual for a volt meter to show voltage and then nothing works with that same voltage, I'm going back there later, so will just check all 3 bulbs, it's possible who knows il let ya know  thanks kev
1990 foretravel grandvilla, Oshkosh chassis
8.2ltr Detroit turbo

Re: Today I'm gonna try and sort my alternator out

Reply #7
I'm trying to sort through your posts, to understand what you have going on.  I have a few thoughts FWIW:

The two small wires that are hanging loose near the alternator - are either of them hot (have voltage) with ignition switch off, or with ignition switch on?

I'm looking (in your photos) at the small red wire that comes out of the same ribbed cover as the large alternator charge cable, and is connected to the start battery post.  That wire has a ID label on it.  If you can read the ID number, you might be able to find it on your wiring diagram and figure out its purpose.

I am THINKING that your alternator may be a "single wire" model.  That is, all it needs to work is a single charge cable from the alternator B+ post to the start battery positive (+) post.  That is why it started working and putting out 14+ volts in your first test, when you connected it directly to the start battery post on the isolator.

If you connect a "single wire" alternator to the center post on a diode based battery isolator, it most likely will not turn on, because it cannot see any voltage on the B+ terminal.  Or, it may perhaps turn on, but will produce insufficient voltage to fully charge the batteries, because it cannot "sense" the battery voltage.

Now, if I am correct that your alternator is a "single wire" model, then it does not necessarily have a EXCITE terminal.  It might have one, or it might not.  I don't know.  That is why I think it would be very helpful to find a manufacturer wiring diagram.

SO, you have been able to "trick" your alternator into turning on using your switch at the driver position.  Why does this work?  I don't know.  Without a wiring diagram, or a terminal identification diagram, you don't know the purpose of the three small terminals on the back of the alternator.  It is possible that one of them is a EXCITE post.  It is possible that same post was used to operate the idiot light on your instrument panel.  Without more data, this is just guess work.

Caution Note:  Randomly connecting a full 12 volts to any one of the three small posts on the alternator MIGHT possibly let the smoke out.

This is as far as I have gotten in my armchair ruminations.

I think it is safe to say that your alternator, in its present condition, is NOT suitable for use with the diode based battery isolator.

There are ways to work around that.  You just need to decide what you want to do.


1993 U280 SE 40' WTBI, Build: 4359
C8.3 300hp, 6-Speed, Exhaust Brake
960 watts on the roof (6 x 160)
Sorento (or BOLT) on a Kar Kaddy SS
"Nature abhors a vacuum"

Re: Today I'm gonna try and sort my alternator out

Reply #8
I'm trying to sort through your posts, to understand what you have going on.  I have a few thoughts FWIW:

The two small wires that are hanging loose near the alternator - are either of them hot (have voltage) with ignition switch off, or with ignition switch on?

I'm looking (in your photos) at the small red wire that comes out of the same ribbed cover as the large alternator charge cable, and is connected to the start battery post.  That wire has a ID label on it.  If you can read the ID number, you might be able to find it on your wiring diagram and figure out its purpose.

I am THINKING that your alternator may be a "single wire" model.  That is, all it needs to work is a single charge cable from the alternator B+ post to the start battery positive (+) post.  That is why it started working and putting out 14+ volts in your first test, when you connected it directly to the battery post on the isolator.

If you connect a "single wire" model alternator to the center post on a diode based battery isolator, it most likely will not turn on, because it cannot see any voltage.  Or, it may perhaps turn on, but will produce insufficient voltage to fully charge the batteries, because it cannot "sense" the battery voltage.

Now, if I am correct that your alternator is a "single wire" model, then it does not necessarily have a EXCITE terminal.  It might have one, or it might not.  I don't know.  That is why I think it would be very helpful to find a manufacturer wiring diagram.

You have been able to "trick" your alternator into turning on using your switch at the driver position.  Why does this work?  I don't know.  Without a wiring diagram, or a terminal identification diagram, you don't know the purpose of the three small terminals on the back of the alternator.  It is possible that one of them is a EXCITE post.  It is possible that same post was used to operate the idiot light on your instrument panel.  Without more data, this is just guess work.

Caution Note:  Randomly connecting a full 12 volts to any one of the three small posts on the alternator MIGHT possibly let the smoke out.

This is as far as I have gotten so far.  I think it is safe to say that your alternator, in its present condition, is NOT suitable for use with the diode based battery isolator.  There are way to work around that.  You just need to decide what you want to do.
Yes, I have decided and for a start I've ordered a normal marine battery isolator as you can see in pic  the same as I have on the boat, yes I am wondering myself about that small red wire and where it goes, I meant to check that earlier and forgot to ask about that,  as for the 2 wires I mentioned earlier, I know what they are for, they were attached to a very very small pipe that goes into air intake, it was for the old ether container I used to have fitted for cold startand I cable tied them together cause the white wire is hot when I push the ether switch up front, but we don't get mutch colder than minus 1 or 2 in the winter where I live, so I disconnected that years ago, it's just come to me what them wires are and they are actually taped to the little pipe I remember doing that now,  the main thing at the moment I've got partial success with now getting 14.2 volts going in now it's wired like bret mentioned in Nitehawks post, once my new manual isolater arrives that will be fitted,  and yes your right I have to be careful when testing the other terminals on the alternator that I don't fry anything,  I was going to have a look again this evening but will leave till tomorrow morning, but what I'm going to do to test them is have the engine running and first get the volt meter on each of those other spare terminals and see if there is any power coming  from any of them,  then il put the volt meter with power on the other  side and check for ground on each terminal with engine running, and also with engine switched off, whatever I do I know I can't risk just touching terminals with hot wire in the hope it will be the right one  I will have to be careful take my time, il write everything down as I go, and as long as I use a bulb with an in-line fuse to test after the volt meter test everything should be OK,  the problem I think is my alternator come from Taiwan, so it's possible that it's not a genuine Leece neville alternator, prob an aftermarket or remanufactured, I don't know to be honest, it looks identical to my old alternator and it fitted perfectly on the original mounts,  that's another thing I can't seem to see any markings on each terminal a letter or something or a number, but there is nothing I can see 
              Kev
1990 foretravel grandvilla, Oshkosh chassis
8.2ltr Detroit turbo

Re: Today I'm gonna try and sort my alternator out

Reply #9
OK, so that answers the question about the two loose wires.  I also removed the OEM ether injection device from our coach.

I've been reading about 2-wire alternators with dash warning lights, and watched some youtube videos.  I think I understand how they work, and how the idiot light in your coach should be connected.  Reading your notes on your experiment, it sounds like you also understand how the light should work.

The idiot light should have one wire connected to switched 12 volt power (ignition switch).  The other wire connects to a terminal on the alternator.  This terminal is usually designated the "L" terminal, for Indicator Light.

When you turn the ignition key to ON, 12 volts is sent from ignition switch to the idiot light.  The wire going to the alternator serves as the ground connection, and the lamp illuminates.

When you start the engine, the alternator starts generating voltage, and the "L" terminal at that time will have 12 volts on it.  When this happens, the idiot light is seeing 12 volts on BOTH connecting wires, and it goes out, telling the operator that the alternator is working properly.

With the engine running if the alternator fails, or the drive belt breaks, then the 12 volt power on the "L" terminal disappears and it again becomes a ground connection.  The idiot light comes on, warning the operator that they have a charging problem or failed alternator.

SO, the big question is, does your alternator have a dedicated "L" terminal?  I don't know.  That's why it would be nice to have a wiring diagram.

I think the test you propose sounds like an excellent idea:

"What I'm going to do to test them is have the engine running and first get the volt meter on each of those other spare terminals and see if there is any power coming  from any of them,  then il put the volt meter with power on the other  side and check for ground on each terminal with engine running, and also with engine switched off."

If one of the small terminals is really a "L" terminal, it should be a dead ground when the engine is off, and it should have a full 12 volts on it with the engine running and the alternator generating 14+ volts.

Let us know what you find out!
1993 U280 SE 40' WTBI, Build: 4359
C8.3 300hp, 6-Speed, Exhaust Brake
960 watts on the roof (6 x 160)
Sorento (or BOLT) on a Kar Kaddy SS
"Nature abhors a vacuum"

Re: Today I'm gonna try and sort my alternator out

Reply #10
OK, so that answers the question about the two loose wires.  I also removed the ether injection device from our coach.

I've been reading about 2-wire alternators with dash warning lights, and watched some youtube videos.  I think I understand how they work, and how the idiot light in your coach should be connected.  Reading your notes on your experiment, it sounds like you also understand how the light should work.

The idiot light should have one wire connected to switched 12 volt power (ignition switch).  The other wire connects to a terminal on the alternator.  This terminal is usually designated the "L" terminal, for Indicator Light.

When you turn the ignition key to ON, 12 volts is sent from ignition switch to the idiot light.  The wire going to the alternator serves as the ground connection, and the lamp illuminates.

When you start the engine, the alternator starts generating voltage, and the "L" terminal at that time will have 12 volts on it.  When this happens, the idiot light is seeing 12 volts on BOTH connecting wires, and it goes out, telling the operator that the alternator is working properly.

With the engine running if the alternator fails, or the drive belt breaks, then the 12 volt power on the "L" terminal disappears and it again becomes a ground connection.  The idiot light comes on, warning the operator that they have a charging problem or failed alternator.

SO, the big question is, does your alternator have a dedicate "L" terminal?  I don't know.  That's why it would be nice to have a wiring diagram.

I think the test you propose sounds like an excellent idea:

"What I'm going to do to test them is have the engine running and first get the volt meter on each of those other spare terminals and see if there is any power coming  from any of them,  then il put the volt meter with power on the other  side and check for ground on each terminal with engine running, and also with engine switched off."

If one of the small terminals is really a "L" terminal, it should be a dead ground when the engine is off, and it should have a full 12 volts on it with the engine running and the alternator generating 14+ volts.

Let us know what you find out!
yes defo chuck il let you know I'm off to bed now hoping to get up early and do some testing, it's funny it's surprising how mutch I've learnt over the years especially when it comes to electrics, I get a sense of satisfaction when I solve a problem and never afraid to ask anyone for advice or ideas, catch ya tommorrow have a nice evening
1990 foretravel grandvilla, Oshkosh chassis
8.2ltr Detroit turbo

Re: Today I'm gonna try and sort my alternator out

Reply #11
Well good day to you all
Hya chuck, I've done all the tests today, and I'm still no father forth, I wrote down all the tests I did and have uploaded a photo, it's so strange results but here goes, the top post with black wire coming out of it and going into the alternator somewhere I've labeled number 4 was giving out 12.4volts, and when engine running  0 volts, I thought I had cracked it, all the other terminals were showing 12.19 volts, before I started engine and once engine was running they all went down to 7 volts so I chose terminal no. 4 as the source for ignition light using a 5watt bulb, but same problem as yesterday, I connected bulb between b+ and the other side of bulb to terminal 4 with ignition on but it wouldn't light up even though the volt meter showed 12.4 volts when connected meter to that terminal and b+  I was still not getting the bulb to light, forgetting the bulb for the mo it all works fine, I don't even have to rev it to over a 1000rpm, just a tap on the throttle pedal and uts charging 14.2 volts and then after a few minutes, it drops to 14 volts and stays at that, so I'm happy with that and once my new isolator arrives that is gonna be fitted where the diode base isolater is at the moment,  although it is bugging me a bit, I'm mot really gonna worry too mutch about the ignition light as I have my dashboard volt meter anyway, but I did find an interesting topic on Google and they wreckon for it to work you must use a 2.2 volt bulb something to do with the resistance, I've took the photos and they will be uploaded after I finish this tex it does explain quite clearly so anyway I've ordered 2 x 2.2watt bulbs they should arrive in a couple days, and if that doesn't work I'm not gonna let myself get stressed about it, it's not that important, have read and let me know if it makes sense,  also on the back of alternators there is a terminal that you can use to run a hand held rpm gauge for testing different things, but which one is anyone's guess, there are no letters or numbers stamped by each terminal let me know what you think  kev
1990 foretravel grandvilla, Oshkosh chassis
8.2ltr Detroit turbo

Re: Today I'm gonna try and sort my alternator out

Reply #12
To me, it looks like your tests confirm what I am thinking about your alternator:

1.  In my opinion, your alternator is a single wire, self-excited, non-DUVAC model, that does not support connection to the idiot light in your coach.

2.  Single wire, because it only requires one single battery charging cable from the B+ post to the battery to operate.  It would probably still work fine without any ground cable connected to the large negative (-) post, because it would be grounded through the mounting bracket.  However, I would not suggest removing the ground cable - you can't have too many good clean grounds in a vehicle electric system.

3.  Self-excited, because it does NOT require any external excitation wire.  The black wire, attached to terminal #4, comes from somewhere (?) inside the alternator.  It carries the same voltage as the B+ post until the alternator starts working...then it goes to zero volts.  This black wire is providing the "excitation" signal to turn alternator on.

4.  Non-DUVAC because there is no "sense" terminal.  The alternator senses the battery voltage through the B+ charge cable.  It should be connected directly (or through a battery selector switch) to the battery in order to turn on (excite) the alternator, AND in order to self-regulate its output voltage.

5.  This alternator will not support connection to the idiot light because it has no dedicated "L" terminal.  The "L" terminal on an alternator typically stands for "Lamp" and is used to connect to the vehicle's charge warning light.  I would not recommend trying to connect your idiot light wire to small terminals 1, 2, 3, or 5.  From your test, you can see that they do not produce the "battery voltage" signal required to turn off the idiot light when alternator is running.  Connecting anything to these terminals could potentially damage the alternator or the built-in regulator.

Once you remove the old isolator and get the battery selector switch installed, your charging system should be in good shape.  Then you can move on to the next puzzle!
1993 U280 SE 40' WTBI, Build: 4359
C8.3 300hp, 6-Speed, Exhaust Brake
960 watts on the roof (6 x 160)
Sorento (or BOLT) on a Kar Kaddy SS
"Nature abhors a vacuum"

Re: Today I'm gonna try and sort my alternator out

Reply #13
Here is a good DUVAC explanation.....
what is a duvac alternator - Google Search
Tim Dianics
Pam Sapienza
Vader PupZilla Labrador Canine Beast (AKA Pup)
Columbia, MO
1996 U320 4000
2021 Jeep Gladiator, Diesel

Re: Today I'm gonna try and sort my alternator out

Reply #14
That's a brilliant article that Is, il read that again later, seems well interesting, yeah I'm gonna forget red  idiot light all together, we just have strange laws over here about warning lights not working properly, I'm not 100% sure, it may be just an advisory, il have to check that actually, thank for that link  kev
1990 foretravel grandvilla, Oshkosh chassis
8.2ltr Detroit turbo

Re: Today I'm gonna try and sort my alternator out

Reply #15
I've just remembered, chuck mentioned this morning about that small red wire tucked in with the alternator wire, It was very faded but I managed to get the number off the wire, I double checked and it was 6970 on the little whiteboard tag, I've checked my schematics and that number isn't there, maybe it is and I just can't see it    kev
1990 foretravel grandvilla, Oshkosh chassis
8.2ltr Detroit turbo

Re: Today I'm gonna try and sort my alternator out

Reply #16
...chuck mentioned this morning about that small red wire tucked in with the alternator wire...
...I double checked and it was 6970 on the little whiteboard tag...
...I've checked my schematics and that number isn't there...
I wouldn't worry about trying to ID that wire.  I looked on the wiring schematics for our coach, just out of curiosity.  I don't see ANY wires with a 4 digit ID number.  Most wire IDs are a letter and one, two or three numerals.

When you remove your battery isolator, and install the new battery selector switch, you might try leaving that little red wire disconnected from a 12 volt power source.  See if anything on your coach stops working.

If everything still works, then I guess you don't need that wire.
1993 U280 SE 40' WTBI, Build: 4359
C8.3 300hp, 6-Speed, Exhaust Brake
960 watts on the roof (6 x 160)
Sorento (or BOLT) on a Kar Kaddy SS
"Nature abhors a vacuum"

 

Re: Today I'm gonna try and sort my alternator out

Reply #17
Yeah that makes sense actually for all I know that wire could have been part of my old duvac system that I still haven't found if I remember I cut it and taped up the ends and buried back in the loom all I know is it definately ain't Leece neville alternator, even though it said for oshkosh on the invoice and when I saw that it come from Taiwan, I thought it is an aftermarket one, but I can't complain it seems to be a good alternator, and now since I've took the isolater out of the equation I'm loving the extra voltage, thanks
Kev
1990 foretravel grandvilla, Oshkosh chassis
8.2ltr Detroit turbo