Alternator problems, need info/help

[steviee7]

Well my first "car malfunction" found me stuck on the side waiting for tow truck.
It appears to be my alternator. (or so I think)
But my alt. light never came on.
I was drive along, my head lights were on and all of a sudden my car lost power. As soon as I shut my lights off (the car began to run like normal. but eventually died all together. I tried turning the key but did not see my dashboard alt. light go on. THe car turned over once but would not start. As I waited for 30minutes for the tow truck I decided to give it one more try. and it finally started up. still the alt. light was not on. I got towed home and the next day I started the car right up. as it idled the alt light stayed on. If I gave the car gas the light went out. I measured the battery and the voltage was 11.7 before the car was running and after it was running. still the battery at 11.6
So tell me why did the alt light not forewarn me? Is there something else that might be going bad?
I have noticed in the past my headlights pulsate between 100% to 90% brightness. Also lately I've seen the alt light come on and go off and also the light that is under the seatbelt and parking brake lamps. (I forgot what light it is)

Is this normal when the alt is dying or can my battery be dying too. any thoughts?

se

[delaneyd]

I had a similiar problem on my 83 SC where the lights and even the heater/AC blower fan would vary in intensity/speed. I checked all the connections at the alt. and found nothing. I took a chance and replaced the alt---problem gone. Its been 2 years now and the issue never returned.

Just a precaution--check all your battery connections--a broken cell in the battery may cause a similiar condition.

[rick-l]

The alternator light goes on when the aux diodes in the alternator are not conducting AND current is flowing through the field winding. If the regulator is dead or the brushes are worn and not making contact this is the case.

[steviee7]

right now I have my battery disconnected and on a slow charge. (My charger is one of those that will tell me if it the battery is OK.) I've been told that some alts if going bad may overcharge and boil the water in the battery. causing it to go bad. The battery is almost 3yrs old. and in florida I've never had good luck with one lasting longer than 2yrs it seems

se

[delaneyd]

If the battery is being overcharged you can usually smell it--it gives off a sulfur smell and you may even see acid drops/specs on the top of the battery around the caps ( unless you already have a gell cell )

[Wil Ferch]

I hope you understand this:

A fully charged battery is at 12.6V when the car is off.
12.4V = 75% charge
12.2V=50% charge
12.0V= 25% charge
<12 V= essentially a "dead" battery

Under normal circumstances....when you turn the key to start the car, does the alt light even come on on the first portion of "twist" of the key?...even before the starter engages? It should. If not, the bulb itself might be burned out. A burned out bulb can cause an alternator malfunction....do a search.

- Wil

[steviee7]

Thanks Wil, this is where it becomes weird, It is not burned out because I saw it today, but the day before as I started the car the first twist there was no light. Maybe it's going or I have a loose connection somewhere. I tried charging the batt. yesterday and it gave me an error code of not able to charge, seek professional help.
I could buy a new battery but I'm guessing the alt will not charge it or maybe it will. Yesterday I ran the car and took a volt reading at the battery and it said 11.7v. I know it should be higher than that if all is well. I'm thinking my next thing is to fix/rebuild the alt. What reading should I get with a good alt. at the battery while running. and if I do have a dead or dying battery could that cause low charge readings on an otherwise fine alternator?

thanks again
se

[steviee7]

...and so far I do not smell any burnt battery.
I'm currently re-charging the battery again. if it gives me another error code I'm buying a new one. I'll keep you all informed as the day runs merrily forward......

[Wil Ferch]

Your battery is dead.... start there...

Wil

[Lorenfb]

3.2 Alternator Failure Modes, ranked:

1. worn slip rings and/or regulator brushes (>75K miles)
2. failed internal regulator, overcharging
3. failed diodes, the result of incorrect battery AND low charge level
AND high revving after starting
4. bad bearings
5. reversed battery jump starting and/or battery installation

3.2 Alternator Related Problems

1. bad alternator B+ connection and/or starter connection
2. bad battery cell causing excessive alt. load dropping alt. voltage
3. bad alt. light
4. bad ground connections
5. shorted alt. light wire (#61) to ground

[rick-l]

Very nice summary Loren

I would add my alternator brushes / slip rings were worn out at 50,000 miles.

[Thrasher]

I also just went thru a very similar issue with my '84 Carrera alternator/regulator. First it was overcharging intermittently - leading to brightening lights and surging fan speed. So, I replaced the regulator after noting that the brushes (especially one) were quite worn. While doing so, I noticed that the slip rings were worn on the alternator, again one groove much deeper than the other.

My "new" regulator (HUCO) lasted about two weeks - long enough to get me thru a DE. Then it failed and I had the complete undercharging (no charging) and the voltage was 12.0 and below.

I replaced both the alternator and regulator (internal) and all has been fine for over a month (Thanks Kurt V). It's not a fun job, but not that tough. Use Wil Ferch's tech article, as it's specific to the Carrera.

Craig

[Wil Ferch]

Loren will tell you the HUCO is junk...and there are good technical reasons he will say this.

I also used a HUCO and have found it be reliable. A lot would depend ( I guess) on the amount of "recharge" duty you force this unit to provide. Meaning? My car is infrequently driven and would ( normally) put a big strain on the "refill" charge requirements... more so than if it was driven every day. Big reason why so many "garage queens" alternators go at 50K miles...like mine...and like rick-l notes.

However, my car is now on a "chipped" battery maintainer / charger ... keeping the battery at 12.6-12.8V all the time. It keeps the battery at full charge all the time and lessens the load on the alt/reg on subsequent re-starts.

- Wil

[Thrasher]

I can't definitively say the HUCO failed and if it did, I should probably attribute its early demise to my failing alternator. I'll never know b/c I swapped out them both at the same time and all was good.

I also am using a battery maintainer now; not sure if mine from Harbor Freight is chipped, though. I'd better go check the voltage so I don't fry the battery.

On that note - I know Porsche recommends unhooking the battery leads when charging - is there enough current in a maintainer to endanger the DME, etc?

[Wil Ferch]

The "Chipped" chargers are safe to use with regular cables still attached. It senses a drop of 1 volt and then begins a slow rate charge ( 1-1.5 Amp charging rate), until that missing volt is made up. Then it shuts itself off while keeping an "eye" on the resulting voltage level....to see when it drops 1 volt again...pretty simple.

A trickle charger...or HD high rate charger... won't monitor itself this way...

Wil

[Thrasher]

I picked this one up at HF: anyone care to comment if it's worthy of the p-car?

http://www.harborfreight.com/cpi/ctaf/Displayitem.taf?itemnumber=42292

Edit: I just found the following in the user manual:

Battery Float Charger
The Battery Float Charger is used for the
maintenance of wet or gel cell batteries that are
stored or used periodically in such items as
boats, cars, snowmobiles, ATVs, and tractors.
The Float Charger prevents self discharge of
the battery, while maintaining and extending the
life of rechargeable 12 volt batteries. It
maintains a battery charge for batteries rated
from 5 to 125 amp-hours, by providing a
constant (minimum current) 13.5 VDC
regulated output. Other types of chargers
provide a strong, rapid charge but tend to boil
out liquids and decay electrodes.
It is simple to use. Hook it up, plug it in and
forget it.

[rick-l]

Originally posted by Thrasher
I picked this one up at HF: anyone care to comment if it's worthy of the p-car?

http://www.harborfreight.com/cpi/ctaf/Displayitem.taf?itemnumber=42292

Since this http://www-s.ti.com/sc/ds/uc3906.pdf costs 2.75 in quantities of a thousand and I am told it is used in the Schumacher charger, and you paid $7.50 total I doubt you have that "chip" charger mentioned above.

However that does look more complicated than the trickle charger I used on my motorcycle for years. It could be doing the constant current and constant voltage states the chip does (the only states you care about anyway).