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General Information => Troubleshooting => Topic started by: Smokey Eddy on February 03, 2012, 11:15:43 am
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I searched for advice on replacing alternators and charging dead batteries with the alternator and found nothing. So here goes...
I replaced my alternator due to burnt diodes and am left with a very dead, <half a year old battery. I changed from a 65 amp to a 90 amp and got a jump start from a friend. Her car was charging at about 13.2v. When I pulled the cables off my battery V dropped to 10.8v. So I connected them again and reved it good n proper. My make shift multimeter now said 14.0v steady. I took the cables off a second time and it held 14.0v. I waited about ten seconds. Turned my meter off and on again (IT crowd reference) and it still said 14 so I thanked my friend and she went on her way. No less than 5 minutes later I noticed the lights were dim. The voltage was so low now on my battery that my meter couldn't read it.
So my guess is that my battery I have now is too dead to give the alternator the minimum 12.6v required and I need to charge it first my other means.
I also couldn't help but notice the battery light never came on even when the car was dead? The glow plug light came on and off a couple times though.
EDIT: I now know that my old alternator did not have burnt out diodes. The flickering battery light had to do with the build up to what ever issue im experiencing now.
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1. It is possible to kill a battery by leaving it uncharged for long periods. It might not work again, ever.
2. It's really not the best idea to charge your battery from a completely dead state using only your alternator, especially a relatively small alternator like the 65 amp. It's a lot of load on that alternator, try to use a battery charger if you can, some parts shops around here will charge it your you for $5-10.
3. Try to find a high frequency battery charger if you can. That means it actually delivers high frequency electrical pulses to the battery while charging it. That helps knock off some of the deposits that build up on the lead plates which kill the battery, so they sometimes work to restore a battery that is otherwise bad and will not charge.
4. The way the battery light works is that it is connected through the alternator exciter wire. Being that it is a light-emitting diode electricity will only flow one way through it, which is when the alternator is not charging. If your exciter circuit is not connected, or not working, the battery light will not come on at all, even when the key is ON but the engine is OFF. Make sure the exciter circuit (usually a blue wire) is providing battery voltage to the alternator when the key is ON, engine OFF. It is necessary for the alternator to work and charge properly.
edit: I've also heard conflicting stories about repeatedly disconnecting your battery cables while the car is running. Some say it can kill your voltage regulator, which would leave you with no alternator output.
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I would say you have at least one issue maybe two. The first is once the car starts its designed to run off the alt not the battery so somewhere your charging system is amiss if dropping from 14 down to 10 and change with no additional load. I would agree with above check that blue wire and make sure battery light comes on with key only and goes out after the engine starts. If you never see it even with the key on track the blue wire for continuity. The second issue could be a dead battery though its tough to say. 10. anything is pretty low for a charged good battery but if it were still discharged can't really tell. Just my 2c.
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Ok. I've bought a battery charger (canadian tire had a 2/20/55/150 amp for 50% off) so once the battery is charged I can drive back an hour to my real multimeter. Put it on charge and trouble shoot. Thanks so much for the input.
Here is a question, what if I'm not getting voltage from my blue "charge now" wire? What do I do then? I've replaced the connections on all the wires but its still the original wire.
Prior to my old 65 amp (i just bought a 90) breaking the battery diode would very dimly glow and sometimes come on periodically.
I'm going to go re-clean all the contacts I think. Paying special attention to the grounds...
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I always have run an extra ground from the battery to the alt. I usually never have any problems with grounding.
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Here is a question, what if I'm not getting voltage from my blue "charge now" wire? What do I do then? I've replaced the connections on all the wires but its still the original wire.
Prior to my old 65 amp (i just bought a 90) breaking the battery diode would very dimly glow and sometimes come on periodically.
I'm going to go re-clean all the contacts I think. Paying special attention to the grounds...
Then you need to trace the source of the problem back to the dash/cluster/ignition. Is anything else not working?
Alternatively, you can just run a new wire to it. It needs switched 12 volt power (it will drain the battery if directly connected).
The very faint alternator light glow that you can see on a dark night is caused by the alternator path to ground not being a perfect conductor compared to the the rest of your electrical system. I don't believe it's a problem but perhaps you could directly ground the alternator anyway.
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The very faint alternator light glow that you can see on a dark night is caused by the alternator path to ground not being a perfect conductor compared to the the rest of your electrical system. I don't believe it's a problem but perhaps you could directly ground the alternator anyway.
Hmm, I don't know if I agree. I have a perfect alt-engine ground and a perfect engine-battery ground. Yet I still sometimes see the faint glow, it must be something else.
Now when I say perfect, I mean filed down perfect clean metal to clean metal connections with die-electric grease on them. Even the alt-bracket connection.
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This is all very good stuff. I'll add a ground ( I have about six coming off the negative terminal of the battery Haha!) I do only have one big one however going from a tranny to block bolt and another big one going to the body and then another big 4ga ground going up to the dash/amplifiers.
So ill charge the battery up, ground the alternator directly AND re-wire the blue wire. Could it use the stop solenoid circuit?
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I have been there
Try with well KNOW good acu,after start see voltage.
With old,bad acu, if you start engine turn on some lights and take off + from acu,if he still work put more load and see what you see,some LOAD MUST be on BEFORE take off +.
If ground is OK look like it`s bad acu.
This is for old car I never try on new comuter car
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I got my jetta used a year and a half ago. Things seemed to work ok so I didn't touch things much until the need arose. One day the battery was getting low during a drive and wouldn't restart the next time. Checked alternator and battery out and both were bad.
I was also sometimes getting wierd tach bounces and that faintest of glow of the charge light that I noticed at night.
I found at first in the stock loom there was a couple connectors near the battery that then made their way over to the alternator, near the fan. Those connections were kind of loose so I cut that out and made my own connectors. Helped in that moment but noticed the same thing happen again later. Then I did a continuity test and would get wierd things depending how I jiggled things.
So I just cut off the whole loom up past the battery and ran new wires from that point to their destination in my own protective cover and my car has never done it since? My tach works whether cold or hot, and my charge light goes off after the first rev of the day.
Only other time I have seen my tach react differently now is if the headlights are on but I imagine that is some vw thing, it seems to settle right back in with correct readings when the car is warmed up and the throttle has been blipped.
I looked at the old wires and the loom was rock hard in front of the fan and spots of the wiring were frayed. Perhaps all those heat cycles in front of the fan leads to eventual breakdown.
I also have all new larger grounds, also added one to starter mount bolt hole and alternator for the heck of it.
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damac, Sorry what do you mean by loom? which ones? can you be more specific?
mtrans, I don't understand most of what you said. What is acu?
For some history on my problem the battery is say 6 months old at most and the alternator is brand new (was an attempt at fixing this problem)
I just jumped the blue wire (which i have connected to the post beside the big B+ post that goes straight to my battery) to the fuel shut off and of course i couldn't turn the car off after that but that means the blue wire is getting power.
Im wondering if maybe i mixed up the blue/black and red/black connections and they should actually be reversed?
Can someone confirm this? I have wired it correctly as per the bosch pamflet it came with but someone with a working system would ease my mind a lot more.
I'm going to run a 12ga wire from the body of the alternator straight to the battery and see if that solves anything. I'll also do some tests for continuity and so on. key off, key on, running blah blah blah since I finally found my multi-meter in one of my suitcases.
I'm also going to remove, clean & coat with di-electric grease:
the ground from the battery to the trans/block bolt
the ground to the body
the ground that i have going to the dash (clean it at the battery)
the power wire from the battery to the starter solenoid
the wire coming from the big B+ post on the alternator to the starter solenoid
I'm going to clean them with vinegar if i've got it. (dont have any sand paper for files on hand)
On a side note i noticed some odd behavior possibly worth mentioning. While driving with a freshly charged battery the battery light in the dash would glow dimly and go out and then again and again slowly growing stronger and stronger with the glows.
When the battery was truely dieing and the head lights were dim and the wipers didnt work and so on I noticed the battery light was no longer coming on.
As a test (I had my sockets with me at the store parking lot) I took off the blue wire which caused the battery light to come on while running. - This leads me to believe that perhaps the red and blue wires are switched because I was under the impression that function was the purpose of the red and black wire?
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Here's the data.
At the red wire where i have it now on the alternator i get 8.77v when running.
At the blue wire (and everywhere else) while running i saw and astonishing 16.99V (I had my charger connected to it charging at 12.5v at 20amps for maybe a total of 15 minutes). turned out my multimeter is faulty. Really reads 11.9V
With the key in the "on" possition without starting I saw 0.02V at the blue wire and 0.02V at the red wire.
The battery with the engine off showed 17.00+v... this puzzles me a great deal
While running the battery light was dimly glowing.
I tried grounding (with a spare length of wire) the alternator to the battery, the battery to the body.
I did a continuity test all over and saw numbers no greater than 0.002 on my multimeter. Most were 0.001 (0.000 being zero resistance). I cleaned and greased all connections anyways - this made no difference.
I noticed one connection i must have replaced years ago that leads to the dash that had a bit of corrosion in the connector - Perhaps this is a culprit?
I have a couple questions; What is causing this incredibly high voltage? Why wont' the alternator charge!!! What is causing that light to glow in the dash? Can a bad battery cause high voltage problems? Can high voltage problems lead to charging problems (i would imagine this would conflict with the voltage regulator built into the alternator)? Can this undoubtably damage my new alternator?
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Jfc. That is a nightmare lol.
If the alt is new and the battery new.. I cant see what the problem would be here.. but 17v at the battery!? right after hitting it with 20a though right??
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Well, I must be honest, the battery isn't BRAND new... it's been dealing with this charging issue so it's been drained (not to dead but to the point where it wont start the car) about 4 times. Had the water topped up twice - last time i did it i over filled a bit and lost some acid in the process.
I juiced it good for about 15 minutes at 20amps and then gave it a 10 second fry at 150 amps and when the count down got to zero i started the car and then did my tests.
For running at 17 volts the head lights were surprisingly dim...
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If it has sat dead in the cold and allowed to freeze I do fear it may be toast.. *** son.
Dont suppose you have a friend who would be willing to lend you a battery for a little why for you to run the tests with a different battery in there?
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If it has sat dead in the cold and allowed to freeze I do fear it may be toast.. *** son.
Dont suppose you have a friend who would be willing to lend you a battery for a little why for you to run the tests with a different battery in there?
Very likely I do actually. I could remove my battery and connect the leads with jumpers to his battery for the sake of running the tests. Could even start my car like that ya? and see if my alternator will charge his battery...
the battery hasn't been allowed to sit and freeze for more than ... 2 weeks at the very most and at the very coldest be -13c... but wouldn't the acid prevent the solution from freezing?
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Could probably start the car that way warm, but I think you'd be hard pressed to pull that many amps through jumpers on a cold start..
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Could probably start the car that way warm, but I think you'd be hard pressed to pull that many amps through jumpers on a cold start..
in which case i'll have charged my battery i guess with my charger and can use it to start? then remove the connectors with the jumpers still on buddy's battery
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Just subscribing to this thread, not sure if I have any useful ideas at the time :/
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My best guess right now after light of new events is that the battery drops below a voltage nessisary to excite the alternator due to the battery being a POS mastercraft battery.
Still doesn't solve the dim battery light in the dash though if that is the issue.
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but wouldn't the acid prevent the solution from freezing?
When a battery is discharged the electrolyte is diluted to the point that it is mostly water, therefore will freeze quite readily.
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im currently tracking down a small enough screw driver to change the battery i bought for my multi meter. Then I'll charge the battery (again) and see what happens.
Im expecting to see now, with a hopefully working multimeter, that the voltage at the blue wire will be the exact voltage ill get across the terminals of the charged battery BUT that the battery will quickly (as in over night or more likely within 4 hours) drain to below 12 volts - thus giving me the no charge scenario and with no way of getting out of it :P
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I "reset" my multimeter with a new battery. Brought the battery inside and checked it.11.8v.
Put the charger on it at 20 amps and 13.5 volts. About 4 hours later I checked on it and the charger was still whirring, battery still bubbling and at the posts I got 15.3v.
Is this pretty normal now? Once fully charged I'm going to let the battery sit for 24 hours at 2 amps. Then ill disconnect and wait say 12 hours or so. I'll check it every six hours and my guess is the voltage will drop but we'll see...
To be updated soon!
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so in 48 hours the battery went from 13.8v after being fully charged to 12.9
Is that pretty bad?
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No untill 12.5but on cold and no drive or short,parhaps more.
Good for multimeter,try that A metar betwen + from aku and + kable,no motor run, up to 100 ma is good.
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I dont see how it can read 12.9.. when 12.61 is a fully charged battery.. lol I think your multimeter is still screwed up some.
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I would take it to a place that can run a test on the battery. I have had them that have good voltage until put under load. they would even hold it for days, but then go to start and it would read 10.something. I took it to a battery tester and within 2 seconds of load it was toast.
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Interesting. So, if it was under load and drops to 11 something... that would cause the alternator to stop working?
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Battery now reads 12.72 its been sitting inside since being charged.
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I'm with theman on this. Take it to a shop and have them hook up that great big heater element to it and see what kind of guts this battery has. My guess is that it will not hold up long. Takes a charge but won't keep it. The cells are gone.
Buy a new battery.
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I'm with theman on this. Take it to a shop and have them hook up that great big heater element to it and see what kind of guts this battery has. My guess is that it will not hold up long. Takes a charge but won't keep it. The cells are gone.
Buy a new battery.
Okay, so the problem is then (im trying to be sure about the root of my charging problem here so please bare with my persistance) the battery drops below, even with the alternator juicing it, the voltage required to tell the alternator to continue to charge?
I'm convinced i need a dedicated alternator ground/more grounding from the dashboard. The battery light comes on and off in pulsing waves. Did i mention that? I'm going to try a dedicated ground (not a bad idea anyways) and see if it charges then.
New batteries are expensive if they are not needed. I can't exactly go to a shop im living on a mountain ski resort. But I can go with a friend to buy a cable to ground the alternator to the battery.
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bump?
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Smokey, Your status is: I can't exactly go to a shop im living on a mountain ski resort.
I take it you are not there for use of the resort, in your Land Rover with two girls, one on each arm.
More like you are chained to the lift as the operator watching them all go by. And without a decent battery you are also stuck there. So, can you get your hands on an amp meter and see what that alternator is doing work wise? Kind of sounds like both sides of the charging system are messed up. No good storage in the battery and no good charging when running. So, now you can't start it and keep it going off the alternator.
Hate to say this but in your situation I would be looking to take both parts to town and have them tested. You are going to have to leave sometime, the snow is going to melt in a couple months. Start making arrangements. I think you have two funerals on those parts.
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The alternator is literally brand new... I haven't driven the car with it on anywhere.
I got a ride to town and had my battery tested and it tested as "good" on a load test but any kind of load it drops to 12.4 volts at full charge. I had my warranty papers so I just told them after an hour of bickering I wanted a new battery and eventually got it. My charger said it was 75% charged so I trickled it at 2 amps and it was fully charged after about 2 hours.
I'm going to see if I can get the belt tighter, add a dedicated ground I have the wire for now (and eyelets), and see if it will finally charge its self.
Could the alternator be charging but I still get less than 13v coming out of it?
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And yes I work on the mountain but not as a lifty :p
I appreciate the comments. Thank-you for reading.
Just a side note; on the alternator, I get 6v at the red wire and the battery voltage at the blue wire. Is this normal?
If I fully charge it I can drive to town and back in the day light and a shop says they can test everything for $25.
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If I fully charge it I can drive to town and back in the day light and a shop says they can test everything for $25.
Yes do this, unplug your headlights (daytime why have them on?) and don't use anything electrical. Beauty of a Mk1, is I don't have to unplug my headlights when alts fail. lol
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So i took the battery to canadian tire with my warranty papers to have it "tested" so they cold say it's bad and give me a new one.
I brought it fully charged (from the night before) and their machine said it was discharged. I waited an hour while it "charged" on their machine and eventually (before the progress bar had reached the end point) it spits out a piece of paper saying "690 cranking amps, 12.2V, battery status:good"
I gave the guy a blank stare and said "i installed a brand new bosche alternator that specifically says the battery needs to hold at least 12.6 volts..."
He looks at me empathetically and says
"yeah... that voltage seems a little low but your car will still start with it..."
"Yes, but what good is a running car with no charging system... it needs to see 12.6 to even start to charge..."
"well how about you take this one back [to the ski resort an hour away] and if it gives you trouble again and we'll swap it"
"okay, well i'll be here tomorrow. I can already tell you that with 100% confidence... will you be here tomorrow to help me?"
"... I'll just give you a new battery"
"Thank you"
This one now has held 13.4 for 3 days straight and my charger gives it a 95% charge and when i set it to charge at 2 amps it fully tops it up in about 5 minutes. Will put it in the car tomorrow and i should hopefully see charging volts coming out of the alternator! :D
If not this post will be promptly followed by a desperate, crying, sad, frustrated post so... consider this fair warning.
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No Whiners Allowed
Sounds like you may be on your way to success with this trouble. Now if the battery didn't fubar the alternator all will be good.
I didn't think it was taking a charge like it should. 12.2 and then throw some of that cold you have on it, might end up 9.0 volts and that is not going to crank a diesel over.
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I find that even a slightly weak battery is just hell to start.. Damn 400psi! lmao
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If I fully charge it I can drive to town and back in the day light and a shop says they can test everything for $25.
Yes do this, unplug your headlights (daytime why have them on?) and don't use anything electrical. Beauty of a Mk1, is I don't have to unplug my headlights when alts fail. lol
why would you have to un-plug them on a mk2? they dont come on when the e-brake goes off like the mk3 cars..
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Oh, I forgot the mk2's had daytime running lights. lol
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Batteries are a right royal pain in the arse sometimes.
Some pointers for testing.
If you can see inside and.....
There are nice plates, chocolate brown, and battleship grey, and covered in liquid, things might be good.
If instead of the above, it looks like a mess of crumpled paper thin plates, the battery is worn out.
If dry, the charging system might have cooked the battery, distilled water might save it, but unlikely, dead battery and deranged voltage regulator.
Note, dry plates are dangerous as they can spark and explode the battery.
Charge the battery on a battery charger for a few hours then let it rest for ten minutes, if you get less than 12.5v and more like 10.5v you have a shorted cell, the car might start but will burn up the alternator trying to get it up to 14.4v.
Good charging system will see 14.4v across the battery with the engine running and no higher.
Batteries do wear out.
A battery that is discharged, say 12v or less is empty, once charging with a slow battery charger, the longer it takes for the battery to get over 14.4v the better, as that is when it is full. Once all the lead and sulphate have been electroplated out, the next substance to get electroplated is the oxygen and hydrogen in the water, this is why the voltage rises when the cells start bubbling. After charging The battery voltage slowly drops as these bubbles float off the plates.
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Oh, I forgot the mk2's had daytime running lights. lol
They did?
I thought it was like 1996 and up, at least here in the states... unless Canada got it earlier, which would make sense.
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Oh, I forgot the mk2's had daytime running lights. lol
They did?
I thought it was like 1996 and up, at least here in the states... unless Canada got it earlier, which would make sense.
Every late 80's vw i've seen has DRL. I know my gf's 90 has them, and so did the 91 golf and 90 jetta i scrapped.
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Oh, I forgot the mk2's had daytime running lights. lol
They did?
I thought it was like 1996 and up, at least here in the states... unless Canada got it earlier, which would make sense.
Every late 80's vw i've seen has DRL. I know my gf's 90 has them, and so did the 91 golf and 90 jetta i scrapped.
only 96 and newer mk3s have them in the states.. nothing mk2 ever got DRLs AFAIK.. and ive even seen some early 96 jettas WITHOUT DRLs..
nothing that i have layed hands on atleast.. and ive worked on LOTS of old VWs.
Jer, you DO know what DRLs are, right?
it means the headlights come on basically any time the car is moving..
it doesnt mean PARKING LIGHTS.. all cars VW ever made had parking lights.. but only 96 and newer got them in the good ol' U S of A..
NONE of my mk2 cars have ever had DRLs.. and my wiring diagrams dont even show it as an option, and my wiring diagrams are very thorough.. they show canada only options, mexico only options, USA only options, and not once have i ever seen mention of DRLs on a mk2 VW..
those 3 mk2s you mention must be the only ones on the planet with DRLs..
so, Jer, do the headlights on your girlfriends car come on when you release the e-brake? thats how the early DRLs functioned..
remember, DRLs are headlights that are basically always on, any time the car thinks its moving, or running, not amber parking lights..
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Jer, you DO know what DRLs are, right?
it means the headlights come on basically any time the car is moving..
it doesnt mean PARKING LIGHTS.. all cars VW ever made had parking lights.. but only 96 and newer got them in the good ol' U S of A..
so, Jer, do the headlights on your girlfriends car come on when you release the e-brake? thats how the early DRLs functioned..
remember, DRLs are headlights that are basically always on, any time the car thinks its moving, or running, not amber parking lights..
Is anyone that unintelligent? ;D :D
Yes I know what DAYTIME RUNNING LIGHTS means. Yes I also know what parking lights are. No ebrake function on any of the mk2's
I've seen. Girlfriends car is a 90 Wolfsburg built Jetta, it has DRL. The headlights are always on when the key is. My gf's sister drives a 94 mexican Jetta, it too has DRL's.. but hers has the e-brake kill switch. The two cars i scrapped were mexican as well. 91 golf base model, not even power steering, na diesel. and another 90 Jetta TD. both had DRL.
Must just be Canadians being safer than you guys.? lol
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If you have a Bentley it's on page 272, daytime running lights for Canada bound cars, from what looks like 1990 and up.
I question the effectiveness of DRLs, at least in this climate... the weather is just not inclement enough. In fact, I had the A/C on today. ;D
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wow, sorry dude.. never knew about DRLs on canada cars..
damn canucks and your superior VWs..
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wow, sorry dude.. never knew about DRLs on canada cars..
damn canucks and your superior VWs..
I wonder why they never came on the US cars?? seems weird to me. Less money I guess, easier to build.. blah blah
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They are a safety feature, given the terrible drivers up north VW thought they would help them out a bit and gave them those auto on lights. The US got them later as the Safety Council looked around and said " Hey those guys got extra lights on their cars and we can see them a whole lot better because they do, best get some on cars here too."
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wow, sorry dude.. never knew about DRLs on canada cars..
damn canucks and your superior VWs..
I wonder why they never came on the US cars?? seems weird to me. Less money I guess, easier to build.. blah blah
DRLs became mandatory in Canada starting with the 1990 m/y IIRC.
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thanks for all the discussion guys.
Coming back to the topic for a moment I have an update.
I got a new battery and charged it at 2 amps. It held 13.2v. I added a ground from the mounting bolt of the alternator to the battery terminal.
I tightened the belt which I now see needs changing - brittle. At first when I turn the key on the voltage dropped to 12.3v. Started just fine even in the cold and the voltage came up to 12.5v.
Slightly puzzled I put the charger back on it and set it to 20 amps. It said the battery was discharged at 60%... after about 2 minutes with the car running and the charger on it the alternator kicked in and it shot to 14.2v in about 30 seconds. I turned the charger off and it held steady at 14.23v.
Seems like the alternator needs a relatively high voltage to spark that charging cycle... any tips on making sure it sees that 12.6v even after cycling the glow plugs and running a small lift pump for that time?
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I would also like to add that the addition of the independant grounding of the alternator straight to the battery with some pretty thick gauge welding wire has eliminated the dim battery glow/pulse in the dash... but the dim glowing could have also been a result of the alternator not charging.
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Revving the engine doesn't give the alternator enough juice to fire up the charging circuit eh? Well I may be time to rebuilt the alternator. Or have a second small battery on line with a switch inside and once the engine is running you hit the switch giving the extra volts needed to trip the charging circuit. Much like you did with the charger deal. But I would be looking at why is the extra voltage needed. Some contacts sticking in the alternator? A circuit board out of whack? Why does it need 13 volts to flip that over to charge. Mine doesn't.
I still need an extra fat wire from battery negative to ground on the alternator to keep that flicker at bay. Thanks for reminding me on that one.
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Or have a second small battery on line with a switch inside and once the engine is running you hit the switch giving the extra volts needed to trip the charging circuit. Why does it need 13 volts to flip that over to charge. Mine doesn't.
I thought the same with the extra battery.. but that would be foolish.
IIRC, his alt is brand new. So is the battery now. No battery should show above 12.2-3 after starting the vehicle, should it?! why does his system demand the unobtainable?!
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Yes Jeremy, the alternator has 40km on it (during which it did nothing). The battery has 0km on it :P. I put it in the car yesterday after charging it at 2amps (even though it was already charged i made sure it was really good n proper charged).
I could do the inline battery idea. I could even make a battery pack out of ten 1.5v recharchables to make 15V and just spark it with a momentary switch.
But I would prefer to get to the root of the problem.
I need (would appreciate) someone to explain to me when the alternator charges? what tells it to charge exactly? how does it work? is it the blue wire that tells it to charge?
as far as i can tell that blue wire is just a possitive battery wire when the key is on.
And why does my battery light not come on if it's not charging? and does a voltage below 14v mean it's not charging?
The battery now reads 12.45 not running.
Footnote: the car is currently stuck in the snow and i need a couple buddies to help me push it out of the hole it's in. The car has sat while about a meter and a half of snow (accumulatively) has fallen on and around it. I keep clearing the snow off so i can get in it and open the hood n junk but i can't seem to drive it out. i WISH all VW's had quattro...
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I need (would appreciate) someone to explain to me when the alternator charges? what tells it to charge exactly? how does it work? is it the blue wire that tells it to charge?
as far as i can tell that blue wire is just a possitive battery wire when the key is on.
And why does my battery light not come on if it's not charging? and does a voltage below 14v mean it's not charging?
-when you turn the key to the on position, current flows through the charge light and on to the alt. regulator (via the blue wire), which provides field current or "tells it to charge"
-the light turns on b/c the d+ terminal (blue wire) is grounded until the alternator begins to charge, at which point the light goes out due to battery voltage on each side of the light
-if the battery light does not come on when the alternator is not charging, there is a problem either in the light circuit or the regulator.
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So assuming the alternator is good and the battery is full charged should he be sourcing a problem with the light circuit?
He says the light does or does not come on with the key? It should come on and once the engine revs up a bit the alternator starts charging. My voltage gauge hovers around 13.2 when I drive. It will pull all the way down to 10 after the glows are on and I hit the starter. Once running it jumps right up. Never really fluxes even with lights or heater fan or defroster thrown into the mix. Amp gauge flutters a bit but not much.
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Okay I just got some more info.
With the key ON the light is ON.
When running the light is either completely off or slightly dim/pulsing. Reving the engine at this point makes the light grow very bright (full brightness) and then die down again and pulse.
When connected to my charger (turned off) and running, the voltage slowly drops/hovers around 11.5-11.9v.
I turn on my charger at 20 amps and watch the multimeter. It goes straight to 12.00.
after sitting at 12.00 for about 60 seconds it will then become 12.02... pause 12.03... less of a pause 12.04... once at 12.1 it is a tenth every second 12.2, 12.3 then really jumps in about 2-3 seconds to 15.00v and the battery light in the dash is now still dimly glowing or off entirely and the engine is idling faster (probably because of my lift pump seeing the high voltage).
I turn the charger off but leave it connected and the voltage drops immediately to 14.23-14.24v.
Disconnect the thing entirely still sits around 14.23 and the battery light is sometimes glowing (im refraining from saying on because it's never solid) sometimes not...
I can get the alternator to start working but only with the help of the battery charger.
Sounds to me like it's this light circuit. Could i have a cracked fuse? or ... a relay not working properly or do i need a whole new gauge cluster :'( ($$$)
I also just read these threads after posting this above post ^
http://www.vwdiesel.net/forum/index.php?topic=29314.15
http://forums.fourtitude.com/showthread.php?5290185-The-infamous-blue-exciter-wire
I've checked the post that the blue wire is connected to numerous times. It always shows the exact voltage that i get across the battery when the car is running.
Is there some way of lowering the required voltage by the alternator to start charging? because as far as I can tell as soon as it see's a voltage over 12.3 (or something very close to that) it starts charging on it's own.
If there was a problem with the battery light circuit wouldn't it not work at all? especially after i disconnect the charger? This question is almost rhetorical as there is obviously a problem with it because the light is glowing dimly while running.
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I have a feeling the other end of the blue wire circuit is not grounding correctly/easily. I work in the morning and it's now 1:30am so I should go to sleep. I'll unplug the gauge cluster tomorrow and see how much resistance i get on the blue wire grounding to the start ground up front or ... something like that. Perhaps I need to add an independant ground going from the cluster to the battery. I already ran a ground from the battery to the dash for the cluster of grounds found under/behind the fuse box panel.
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I have a feeling the other end of the blue wire circuit is not grounding correctly/easily. . Perhaps I need to add an independant ground going from the cluster to the battery.
Maybe I confused you with my previous post...the blue wire grounds through the alternator, not at the cluster. If the light is on when key is on, chances are the cluster is not the problem. There may be a problem with the alternator or the blue wire. The terminal for the blue wire is usually marked D+. How many terminals are on this alternator and how are they marked?
Turn the key on (engine off) and remove the blue wire. Connect your volt meter between end of blue wire and batt-. What do you get? What does the light do? What do you get if you connect your meter between b+ and that terminal? Then start the engine and take the above readings again.
As ORCoaster has alluded to, and I have experienced myself (with a fresh rebuild), sometimes an alternator will not begin to charge until the engine is revved a bit. I have been told Bosch alternators are notorious for this. This is because the output of the alternator stator also supplies the regulator with current. There is residual magnetism in the rotor which will induce more current into the stator the faster it spins. Just for fun, try revving the engine to 3-4 k RPM and see if the alt starts charging.
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I'm aware of the reving issue and I've been doing that to no avail. I will take those readings and post them.
This alternator has identical posts and inputs as the old 65 amp one did.
I'll also make sure the nuts on the post are not grounding to the body of the alternator.
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Okay so when i took the blue wire off the alternator and grounded it through my multimeter i only got 6.5V with the key in the ON position and when the engine was running it was 6.9V...
But it doesn't end there...
If i start the car without the blue wire on it at all and i check the D+ post i get 0.65V.
If I connect the blue wire to it (or any wire supplying voltage like from the B+ post) I get the battery voltage. I take these wires off with the car still running and check the D+ post I still see the battery voltage. This sounds totally wrong to me... Either that or i don't understand anything. I was planning on temporarily fixing this by jumping the B+ to the D+ but clearly this is already happening and doesn't do anything.
One thing i did notice was i could turn the head lights on and off by grounding the blue wire (turns them off) and then touching the D post turned them back on again.
I'm completely lost now. No idea what is wrong or what to do next...
(http://i49.photobucket.com/albums/f279/edmcclung/IMAG0788.jpg)
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Here is a question, what if I'm not getting voltage from my blue "charge now" wire? What do I do then? I've replaced the connections on all the wires but its still the original wire.
Prior to my old 65 amp (i just bought a 90) breaking the battery diode would very dimly glow and sometimes come on periodically.
I'm going to go re-clean all the contacts I think. Paying special attention to the grounds...
Then you need to trace the source of the problem back to the dash/cluster/ignition. Is anything else not working?
Alternatively, you can just run a new wire to it. It needs switched 12 volt power (it will drain the battery if directly connected).
The very faint alternator light glow that you can see on a dark night is caused by the alternator path to ground not being a perfect conductor compared to the the rest of your electrical system. I don't believe it's a problem but perhaps you could directly ground the alternator anyway.
I don't understand how running a switched 12V wire to the D+ post does anything at all if the D+ post puts out the battery voltage ANYWAYS? To me, it's like running a power wire into another power wire and expecting something to change or be different.
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Read this Eddy to help you undestand how the system should work: http://www.pelicanparts.com/techarticles/914_alternator_troubleshoot/914_alternator_troubleshoot.htm
Look at the wiring diagram. He talks about 4 terminals but note that 2 of those (DF and D-) are internal between the alt and regulator.
D+ acts like a ground for the dash light until the alternator starts charging, at which point D+ should have the same voltage as B+, causing the light to go out due to the same potential present on both sides of the light.
When you took your voltage readings, are you sure you had a good ground for your meter? I like to go to batt-. There's something not right if you can control your headlights through the blue wire. I would look at a schematic to see what these circuits have in common...
So when you jump from b+ to d+ the alternator doesn't begin to charge, ie. voltage from the b+ terminal doesn't start to rise? Even if you rev the engine a bit? If not I suspect something wrong with the alternator...let us know.
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I just did a few trials and here's what I have.
With the blue wire disconnected the entire time.
With the key in the ON possition:
Battery: 12.06v
D+ to (-): 0.50v
D+ to B+: 11.56v
With the engine running:
Battery: 11.5v
D+ to (-): 0.50v
D+ to B+: 11.0v
So then I started to try some things.
Key in the ON possition:
Blue wire hanging free: 7.0v Batt. Light is ON
Blue wire to D+ Batt. Light is ON
Blue wire to (-) Batt. Light is ON
Blue wire to (+) Batt light is dim
Engine Running:
Blue wire hanging free: 7.0v Batt. Light is ON
Blue wire to D+ Batt. Light is Dim
Blue wire to (-) Batt. Light is ON
Blue wire to (+) Batt light is Off <-- Doing this turned on my headlights and they remained on. Blue wire to (-) turned them off again. Pretty sure I should have day time running lights... any ideas with this one?
Then with the Blue wire free I connected the D+ to the (+) of the battery and the engine bogged down as if the alternator was putting on some load and the voltage rose instantly from 11.4v or 11.8v (it's dark out) to 12.8v and then started to fall. I dropped my piece of wire and saw that the D+ post now showed the battery voltage but it was clear the alternator stopped doing what it had so briefly began to do. touching my wire to the (+) post and to D+ didn't seem to do anything at this point.
Remembering when I had my battery charger hooked up to the battery, after some time the alternator did kick in and start charging and then charge on it's own, perhaps the 7.0V from the blue wire is not enough or correct and im losing the rest of the voltage through a short in the line (i derive this via the batt. light being on at all times even if the blue wire is not grounded).
My question now is why does it not start charging again once 12v is applied to D+ a second time...
The fact that the battery light is on when the blue wire is hanging free tells me that circuit is grounding somewhere it shouldn't be and I have a fantastic time ahead of me figuring out where it's shorting. I'm also confident that the problem lies not within the alternator but with the blue wire as I originally had this problem with my other alternator - in retrospect i now regret buying a new one as there was likely nothing wrong with it. This one, once operational, should output 50% more current though which will be nice.
On a side note; from the site dieselweasel linked at the bottom the author says,
"In the Bosch system, the size of the charge warning lamp bulb is critical. Too low a wattage bulb will not supply enough field current for "bootstrap" operation to be reliable. The Bosch book that I have states that the lamps must be at least 2 watts for 12 volt systems. If you have replaced your charge warning lamp recently, then too small a lamp may be your culprit. "
Our battery warning light is an LED that probably outputs 1/4 of a watt... Does the mk2 system compensate for that?
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I don't understand how running a switched 12V wire to the D+ post does anything at all if the D+ post puts out the battery voltage ANYWAYS? To me, it's like running a power wire into another power wire and expecting something to change or be different.
I don't quite understand what you are asking, sorry, but if you want to know why it has to be switched, the D+ exciter wire needs to be switched so that it is not energized when the engine is off... since it is basically grounding through the alternator when the alternator is not producing electricity, it will drain the battery if connected to a constant 12v source.
If you're asking how alternator excitation works, I dunno, lol. But yes, a 12V input is required for it to start making 12V, at which point, the exciter circuit is a electrical source and not an electrical draw... does that make sense. I think it has to do with the fact that an alternator makes power by spinning an magnetic field, but that magnetic field has to come from somewhere, so it is produced by the exciter circuit through the alternator coils until the alternator makes power on its own.
Most alternators have the exciter circuit, but VW just had the clever idea to use an LED through the instrument cluster as part of the circuit. Since electricity only flows one way through a diode (LED) the light only comes on when the alternator is not producing voltage (or in your case, is shorted to ground).
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So how can I temporarily fix this? Switch a wire to the d+ post and ignore the battery light until I figure out this grounding problem?
Or is it that once the alternator starts charging it will continue to do so since B+ and D+ essentially become the same?
Any ideas about the head light bit?
And yes what you said made sense. I read how it all works last night from that link dieselweasel posted. I dare not try to understand the math but I do understand what and why now. I think the main issue now is the electrical demons in the car with the exciter wire and the head lights.
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The fact that the battery light is on when the blue wire is hanging free tells me that circuit is grounding somewhere it shouldn't be
I agree something is wrong in the exciter (blue wire) circuit.
Would be nice to prove that the alternator is working correctly though, and get it charging so you can at least drive the car while figuring out the other problem. Did you rev up the engine at all when you had b+ to d+ jumped? I would try that...
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Just did exactly that. Nothing. Also checked fuses. all look okay. Is there a relay that may not be working properly? Like the load relay or something.
Jumping d+ to + doesn't make it charge on its own but connecting the battery to a charger does. This I know. Reved it to all hell too partially as a test and also in frustration.
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What brand of rebuild was the alt? Some rebuilds can be pretty sketchy. If you can, find an auto electric shop and bring your alt to them to test it. I know you are thinking it is good but I really think it should charge if you put 12v to the d+ terminal. Wouldn't be the first time I was diagnosing a problem and wound up finding two separate issues.
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It's a Bosch 90 amp I bought through bestpricecarparts.ca
Advertised as a new alternator. I paid around $300 for it before an $80 core return.
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I guess ill have to take it somewhere to be tested. perhaps it requires an abnormally high voltage to induce the field. I ask this because as far as I can tell, putting a charger to it will trigger the alternator to start charging and continue to charge once the charger is removed.
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perhaps it requires an abnormally high voltage to induce the field. I ask this because as far as I can tell, putting a charger to it will trigger the alternator to start charging and continue to charge once the charger is removed.
Could be. Like I said, try to take it to an auto electric shop as I would have more confidence in their testing than Cdn. Tire for example. They should be able to give you a definite answer as to what voltage is required at the d+ terminal.
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So I'm pretty confident its a belt problem. Taking the load off the alternator with a battery charger allows the belt to grab the pulley and start spinning. Upon closer inspection the belt is cracking and glazed on the sides. This will be the first time ever the belt has been slipping without any ear piercing screeching sounds. The pulley is also smooth as glass. I'm going to build a better bracket for tensioning, get a new belt and see if I can't sand blast the pulley somewhere or perhaps flap wheel with my dremel.
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Apparently the 7 volts is enough to get it going. its also interesting that it CAN spin bit not fast enough to work properly.
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So I'm pretty confident its a belt problem. Taking the load off the alternator with a battery charger allows the belt to grab the pulley and start spinning. Upon closer inspection the belt is cracking and glazed on the sides. This will be the first time ever the belt has been slipping without any ear piercing screeching sounds. The pulley is also smooth as glass. I'm going to build a better bracket for tensioning, get a new belt and see if I can't sand blast the pulley somewhere or perhaps flap wheel with my dremel.
Ahhhh... The thought crossed my mind that there could be a belt problem but I ASSUMED that checked out ok. Guess that's what assuming does. Glad you found the problem.
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not definite yet. need to fab a bracket
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So this actually turned out to be a complete waste of money-problem. The pulley I have has worn to the point where it will evenly wear a belt until its too thin to properly grib the pulley but at the same time it wont squeel, the wear doesnt look unusual, it will spin everything but silently slip on the alternator.
Only once i had a new belt in my hand i saw how much thinner the old belt was from the new one. It had all the markings still on it but it was too worn to spin the pulley.
My 65 amp alternator is old and has at least 1 burnt diode but it still works if you spin it fast enough, This new 90 amp alternator i suppose is just an expensive upgrade to deal with my high load accessories like a 600 watt inverter, 2 100 watt roof rack lights, higher wattage head lights (135 watts each) and big-@$$ stereo. I guess I can finally add those heated seats & driver seat massage pad.
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Wow, you mean a new belt would have solved the problem in the first place? That would be so bad.
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JFTC. >:( that is full blown retarded.
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Wow, you mean a new belt would have solved the problem in the first place? That would be so bad.
Sort of. the pulley would have chewed it up but all i had to do was gently clean up the insides with my dremel and sand it smooth with medium emery cloth...
But, 65 amps wasn't doing it for me. I think there was a reason i went through 2 batteries in 2 years.
Never the less I'll always check the condition and THICKNESS of my belts from now on.
I wish i had taken pictures of the old belt. It looked fine except for the fact that it was about half the width it used to be.
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I dont know if i ever posted but this is the little bracket i made to make the bigger 90 amp alternator fit with the original 65 amp bracket on an AAZ
(http://i49.photobucket.com/albums/f279/edmcclung/IMG_20120503_180024.jpg)
It works amazingly! I can get the tension just right!
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my 90a alternator bolted into the same spot that my 65a came from.. dunno why you needed anything different for it..
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I think the mounting hole on mine is different because there is no way in hell the arm would reach it. Is your alternator Bosch?
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I think the mounting hole on mine is different because there is no way in hell the arm would reach it. Is your alternator Bosch?
i took off a 65a bosch, and installed a 90a bosch.. direct replacement other than the wiring..
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Weird. Mine is the opposite. Same wiring different body.