Please don't judge......
Been dealing with low charge from alternator since I got Alice.
Finally got looking at it and I only see two charge cables attached.
See attached.
This CANT be right.
Service tech says he saw wires hanging down while underneath.
What color goes where?
Should be numbers on the wires-- check against your wiring diagram.
OR post the wire numbers and someone else with a diagram can look them up.
Moby,
We gonna need more info and some better photos.
1. Are you still running the original type battery isolator?
2. Is your alternator original, or has it been replaced?
3. Do you have any paperwork describing your alternator make or model?
4. How many "extra" wires are hanging down below the alternator?
Can you get some better photos of the back end of the alternator? Pull back a little so it is easier to "get the big picture".
Would be helpful to see all of the terminals, and also a photo of the id plate (or sticker) on the alternator.
Looks like someone did some creative wiring for the DUVAC system your coach had OEM. If you still have the battery isolator then you need to have all 4 wires hooked up. One of the small wires goes to the ignition and the other goes to the sense side. Now you will have to trace which wire is which as the color may lead you down the wrong road.
Like Chuck above we sure could use some more info and better pics.
Mike
Best I could do, for right now as far as new pics.
If it helps, I've located one small wire, yellow in color, terminated at the LEFT heavy duty wire. Most noticeable in the last picture.
By length, I'd guess it went to the left most smaller terminal.
I can't tell anything from those photos. Sorry.
Without some way of identifying your replacement alternator, any advice anybody gives you is just shooting in the dark.
See if the tech can get in there and somehow clean up the area around the small terminals. It would help to know if any of them have any kind of marking. Looking for something like a "S" or a "I" or "SENSE" or "IGN".
Would also help to know where the yellow wire is terminated on the other end. Also where the "extra" wires go.
As a last resort, you may need to remove the alternator and get it out on a bench where you can get a good look at it and make positive ID.
Sorry about the poor pictures.
Perhaps a schematic would help.
(two wires from wiring harness)
Yellow Y1
Blue B1
(both hang free)
Terminal T2 T3
(T1)
REAR OF ALTINATOR
T5 T4
T5 has a large red wire attached to it, T4 Has one large Red wire attached to it. (battery lead) it also has a small (20G?) yellow wire attached to it. Y2
Y2 is only long enough to connect to T1.
I am assuming Y2 is the "exciter" or "IGN" wire as it would constantly have a 12VDC charge on it (assuming battery is charged).
I am also assuming it goes to T1 as thats the only terminal it can reach.
The two other wires (Y1 + B1) are, I'm assuming are the sensor wires - the wires that tell the alternator which bank needs charge based on the voltage delivered. I can (but have not yet) verified that they normally have some charge on them but present 0 VDC when one of the battery's are disconnected. I will do this and hope to find out which color wire goes to which battery bank..
This being the case, I only need to find out which sensor wire goes where.
Yes, I plan on having my much more flexible son in law look for definitive labels.
Other suggestions?
Other than reading the numbers on the wires, easy to differentiate between IGN from SENSE.
IGN will only have 12VDC between it and chassis ground (any clean metal on the engine) with the ignition ON.
SENSE will have exactly the same voltage as the chassis battery all the time.
Again, we don't now if this is an OE alternator or some other variant that is wired differently.
Given that Y2 is directly connected to a battery cable, I'm gonna assume its a sense wire.
Brett, I totally get your caution here, and I plan on using due diligence to figure this out
NO GUESSING.
But, if I have to pull the unit. How hard is it to remove?
Pulling the alternator is not complicated, but can be difficult, depending on how tight the mounting bolts are. Remove the belt, remove the cables on the back, remove the mounting bolts, remove the alternator.
If you start connecting wires (carrying voltage) to the screws on the alternator without knowing what you are doing, you can easily cause damage to the alternator or the voltage regulator.
Can you be specific on your symptoms, like voltage. Also measure voltage at all three of your isolator.
Also nice for me to know your first name.
You have the rear radiator which complicates the removal.
Its Rich.
Symptoms are simple....battery's are not charging unless I run the genny.
Well.......
3/5 ths of THAT is done!
Anybody know if the idler pully right next to the alternator is a spring loaded tensioner ?
How so?
Looks accessible from up top.
If you look in the back of a side radiator coach you will immediately see what I mean.
Yes - pretty easy with no radiator in the way.
The idler pulley on my C8.3 is spring loaded. Use a 1/2" breaker bar to release the tension (which is
considerable so watch yer fingers).
Ok.
So the question becomes, if I HAVE to pull the alternator are y'all saying I HAVE to pull the radiator?
Or, it's just harder with a rear radiator?
Just harder. No need to pull the radiator just to remove the alternator.
Mike
Rich,
Your alternator has two large red cables attached. First order of business is to determine which one is the ground cable. Easy to do - just follow them both to see where they lead. The ground cable is usually short and grounds on the engine block near the alternator. The other cable will be the B+ (charging cable) that goes to the
center post on the battery isolator.
You think the big red wire on the T4 lug is the charging cable, which may or may not be true. However, even if it is true, that wire will
not be constantly HOT because it connects to the
center lug on the isolator, which should not show any
real voltage (unless alternator is turning). With engine off, only the two outside posts on the isolator will read actual battery voltage (unless the isolator has failed).
You think that the small yellow wire is the "exciter" or "IGN" wire, because it is connected to one of the large lugs and can only reach T1. This is incorrect. The "excite" wire on a DUVAC alternator must be connected to a source that is
only hot when the ignition switch is turned to the ON position. Connecting the "excite" wire to a constantly hot source would not work.
You think the other wires (Y1 & B1) are the "sensor wires - the wires that tell the alternator which bank needs charge based on the voltage delivered." This is also incorrect. IF your alternator is DUVAC it will only have one "sense" terminal.
There will only be one "sense" wire. That wire will be connected to a source that reads the START battery bank voltage. It is usually connected to the START battery post on the isolator, but may be connected directly to a POS (+) post on a start battery. Either way works fine.
Your statements above indicate you may not be completely clear on how the DUVAC alternator works. Of course, we don't even know yet if you have a DUVAC alternator. But in case you do, the thread linked below will help explain how it
should work. (If it turns out you
do not have a DUVAC alternator, this discussion will go off in a completely different direction.)
What is DUVAC? (https://www.foreforums.com/index.php?topic=33250)
Chuck,
I'm starting (see what I did there?) to understand more and more.
I'll check both large lines to see if ones a ground and see if B1 or Y1 are the ignition wires.
Still don't understand why there are three small terminals, but patience.
Just flushed the antifreeze out of the water lines, and freezing temperatures forecast for tomorrow. Gotta address that first.
Many alternators have several small terminals that are
not to be used except under special circumstances. This is why it is essential to determine the correct wiring hookup for your specific alternator model.
Link below to a little light reading:
https://www.prestolite.com/literature/tech/alts/TSB-1057_Universal_alternator_wiring.pdf
Rich,
You have a confusing alternator problem. Here is one possible explanation that we have seen several times on this Forum. Your coach was factory equipped with a DUVAC alternator which was specifically designed to work with the factory installed diode based battery isolator and two battery banks. Your original DUVAC alternator most likely had both a "sense" wire and a "excite" wire. So far, so good.
At some point your factory alternator was replaced...probably by a mechanic (or owner) who was not familiar with the DUVAC alternator and the two battery bank electrical system on your coach. This mechanic may have used some no-name generic replacement alternator that he thought would work fine. He thinks "It's just like replacing a truck alternator". So he disconnects all the wires hooked to the old DUVAC alternator, pulls it out, installs the new alternator, and connects the large charging (B+) cable and the ground (NEG) cable. Just like he would on a truck. However, since there is no obvious place on the new alternator to attach the two small wires, he just ignores them and lets them hang down (worst case) or he wraps them with electrical tape and tucks them away (best case).
The happy coach owner drives off thinking he has a nice new alternator. Sooner or later he will discover "it is not working right". In some cases, it might not charge at all because it never turns on (needs a "excite" wire connected). Note: the alternator may come with a short "excite" jumper wire. The instructions will say to connect the jumper between one of the small terminals and the large (B+) charging post (sounding familiar?). On a single start battery truck engine, this will work. It will not work on coach with two battery banks and a isolator. Sometimes the new alternator will be "self excited" and it will turn on and try to charge the batteries, but will not fully charge them due to voltage loss going through the isolator (needs a "sense" wire connected). Sometimes the "mechanic" will try hooking the two small wires to one of the small terminals on the new alternator without knowing what they are for. Often results in damaged alternator, or melted small wires and possible engine compartment fire hazard.
I think this is the sort of scenario that has got you where you are. Once we have a positive identification of your alternator, we will know how to proceed. It may mean simply attaching wires correctly. If your alternator is non-DUVAC there are ways to make it work. Or, you may decide to make some changes to your setup...but you should not do that until you positively ID the alternator (and make sure it is actually functional).
Or, if I can't identify, get a new alternator.
I mean, if it's a hassle to pull why put back a used part?
I agree that may be the best solution. It's your money, and your decision.
Model and vendor suggestions?
Shop around online - items in stock and prices change often these days with supply chain disruptions.
See link below for a recent thread where we discussed replacement alternators. Reply #10 has links to what I believe would be a good
direct replacement unit for your coach.
UPDATE Engine batteries not charging while engine is on UPDATED (https://www.foreforums.com/index.php?topic=41790)
An alternate setup option would be a 160 amp Delco alternator and a Victron argoFET Zero voltage loss battery isolator.
Delco 28si 160 amp 8600308 ~$233. J180 long hinge.
https://www.finditparts.com/products/1881560/delco-remy-8600308?ga_list=Related%20Products
Victron argofet isolator, 200 amps, 2 batteries, ~$120.
Victron ArgoFET Battery Isolator (https://baymarinesupply.com/electrical/isolators-35/argo-fet-battery-isolator.html)
The Delco does not need the excite wire connection. It can use the remote sense wire.
Rich,
I am presently running a Delco 28Si on our coach. I am very happy with it. Link below to my installation thread. Ignore the stuff after the first two posts - I was "customizing" my electrical setup just for fun.
Delco Remy 28SI Alternator Installation (https://www.foreforums.com/index.php?topic=40778)
Agreed, a "standard" alternator will not work properly with a DIODE-BASED ISOLATOR. There is approximately a .7 VDC drop across that type of isolator so batteries will be undercharged. Yes, assuming the excite terminal is jumped to the B+ terminal.
If you are going to stay with the diode-based isolator, you do need a DUVAC alternator, as the sense wire is on the chassis battery side of the isolator. So, what happens is the sense wire tells the alternator to produce approximately .7 VDC MORE than will reach the batteries so the batteries receive the correct voltage.
Moby,
I ASSUME you have used a digital voltmeter to verify the problem. Easiest place is at the diode-based isolator. With engine at 1,000 RPM or so, you should have mid 13's- low 14's at both the outer lugs and approximately .7 VDC more at the center lug which is direct to the alternator B+ terminal. I suggest testing before dismantling anything, as symptoms of a bad isolator are difficult to differentiate from a bad alternator.
Post what you get or PM if you want to visit on the phone.
And, the "non-DUVAC" alternator will work, but not with the diode-based isolator. Either a $$ battery isolator with low loss or a simple ON-OFF switch will work just fine with a non-DUVAC.
I agree that using the OEM alternator is preferred. Mine went out in Kentucky on a busy bridge. So once the tranny didn't have enough voltage to stay in drive there I was. Police had a tow company come out but I was able to get a charger on the engine batteries long enough to get in gear and off the bridge.
The tow company showed up and said they could put on new alternator and get me back on the road so told them to go ahead. They put on a Delco like semis use and when I started the engine it fried the engine wiring harness for several feet. The man hooked it up wrong. Long story short after they towed it to a truck shop they tried to use a non OEM alternator that they couldn't get to work. Finally called Foretravel and they told them only use the alternator that came on it. Total bill was 8500.00 which the tow company covered. So IMHO use the correct one.
Larry
Larry, et al;
If that ever happens again (chassis battery voltage too low to run coach) there is a very easy work around:
Start the generator and turn on the boost switch. The inverter/charger, powered by the generator will charge the house battery bank. Through the boost switch it will charge the chassis battery.
You could drive cross country like that.
And, if both banks too low to even start the generator, a jump from your toad battery should be enough to the the generator started.
I agree that using the OEM alternator is preferred. Mine went out in Kentucky on a busy bridge. So once the tranny didn't have enough voltage to stay in drive there I was. Police had a tow company come out but I was able to get a charger on the engine batteries long enough to get in gear and off the bridge.
The tow company showed up and said they could put on new alternator and get me back on the road so told them to go ahead. They put on a Delco like semis use and when I started the engine it fried the engine wiring harness for several feet. The man hooked it up wrong. Long story short after they towed it to a truck shop they tried to use a non OEM alternator that they couldn't get to work. Finally called Foretravel and they told them only use the alternator that came on it. Total bill was 8500.00 which the tow company covered. So IMHO use the correct one.
Larry
Yes that would of worked but we had just bought the coach and was a emergency trip first time out and didn't know the boast switch relay was bad. Have learned a lot since that trip.
TBH I didn't get the VOM out.
I was made aware of the issue by the dash Guage and audit system reporting falling voltage. Then seeing only the two large cables attached and no excite or sense wires I ASSUMED that was the problem.
Raining and home schooling the grand kids now.
Will attack the VOM measurements and terminal identification (through use of flexible son in law) later and will report back.
Have had the same one as Chuck and Jeanne for 3 years,no problems,upgraded isolator at the same time.