Alternator problems

ddave328i · 09:31 AM

I had the alternator replaced TWICE today and still having problems....

I had replaced it only because it was making one heck of a noise.. (bearings went out)... So I took it in and had it replaced today with a 80 amp BOSCH alternator. It was charging and checked out ok so I drove home. I made a quick stop (about 20 min) at the store and when I came out and started it up, the Battery light was on..
So I took it back and they changed out the Alternator with another new one, tested it, yep charging.. So i went home again.. came out tonight about 5 hr later, and the Battery light is on again... It's not charging...

What is going on...?? The battery is 2 years old and the only reason for changing the Alternator was because of the bearing noise...

Any ideas..?? I am stuck until Monday unless I can fix this...

'96 328i e36

Thank you
Dave

coolbear1 · 01-01-2010, 09:27 PM

Has to be the battery, or wiring if the alternator is good, see if this helps.

ddave328i · 01-02-2010, 09:24 AM

Would a New Alternator cause the battery to die..? I ask this because the old Alternator was charging fine to the battery, I had no issue with the charge or battery before the change, I replaced the Alt. because of the bearings were shot and making so much noise.

I have checked the connection at the battery in the trunk. They are on tight and have no corrosion on it.

I will remove the battery from its hold and check the water level; if it's not a maintenance free battery.

Question: So if the battery is bad, the Alt could not push the charge to it and that would give me the battery indicator light..?

coolbear1 · 01-02-2010, 01:26 PM

You paid someone to replace the alternator, and they say it is good, but it is not charging, how do they explain it? If they are any good at what they do they would tell you what is wrong.
You can take the battery to any auto parts place and they will test it for free.

ddave328i · 01-02-2010, 01:40 PM

Hello Coolbear1,

After he installed the second Alt. He showed me the meter (he attached it to the + terminal on the passanger side neer the fire wall and fender and the - neg. on the engine block. he reved the engine and the meter read 13.50 - 14.35 in that range.

I drove home with no issue. After it sat for 5 hrs. I went to start it up and the battery light is on. So at some point it was charging.

Today I just checked the battery water, it was low and I filled it. starter the engine and still battery light is on.

I will try to call someone and see if I can get there help to take the battery to be tested... As I only have one car.

Dave

P.S. the place that replaced the Alt. is closed on Sat and Sun.. so I called and left a message. I hope to hear from them first thing Monday...

coolbear1 · 01-02-2010, 02:58 PM

Maybe this will help;

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ddave328i · 01-02-2010, 05:21 PM

Ok I took the battery to the AutoZone and they checked it out.. It was good but a little low so they charged it for about 20 - 30 min.

I got it home and in the car, and nothing, still have the battery light on..

So while I was there I bought a multimeter and will check the alt. in the morning.

SO to check the Alt, I will...
Start the car, attached the multimeter to the + terminal on the passenger side near the fire wall and fender and the - neg. on the engine block and read the out put.

Correct..? Or... take a reading for the '+' and '-' from the Alt it self...??

coolbear1 · 01-02-2010, 06:00 PM

ddave328i · 01-03-2010, 10:17 AM

I just checked the it...

Battery with car off = 12.47 volts at the battery in the trunk and from the passenger side ' + ' terminal and multimeter touching a ground to the chassis.
Battery with car started = 11.89 volts at the battery in the trunk and from the passenger side ' + ' terminal and multimeter touching a ground to the chassis.

Power getting to the '+' on the Alternator with car off = 12.45 volts

Power from of the Alternator's negative with car running = 1.43 volts (multimeter touching the negative wire and multimeter touching a ground from the chassis)

So is it that this Alternator is not sending a charge.? I also check the 'charging' fuse #33 in my fuse box and its ok. Checked to be sure that the fuses are getting a good ground.

Or is it my battery..? If the alternator is only pushing out 1.43 volts to the negative side out of the alternator... or did I read it, or do the test incorrectly..??

Dave..

ddave328i · 01-04-2010, 12:35 PM

I went back today to the BMW Mechanic, Since I had left him a message last Thursday (new years eve) I was happy to receive a call a few min. before 8:00am. He sounded concerned and wanted me to bring it in after traffic eased up.

I got it to the shop with no issue other then my hands being very cold seeing that I had to keep the rear window slightly open and the sun roof vent open to circulate some air to keep the windows from fogging up.

He tested it and sure enough it wasn't charging. He had already had another alternator ready. He put something across the ' + ' and ' - ' bolts on the alternator then it started charging again. Battery light went out.

He told me that the 'switch' that tells the alternator to charge or not charge had got stuck in the off or not charging... ( I'm sure it's more detailed then that, but he but it in basic terms for me..)

So he still had my old alt. and check it out to, other then the bearings being bad it was charging fine. So he replace the Bosch alternator with the other one that had arrived this morning. He told me that he had it checked out before it was delivered. He installed it, ran some checks and looks ok.. 14.53v charging and with accessories on 13.79v... If my memory is correct..

So,.. I drove around in the rain and cold with as many accessories on as I could turned on. Wipers, lights, radio, charging my iPhone, seat heaters, rear window defrost, and heat for about 30 -45 min then came appon a mall and parked it, turned it off and let it sit for about 20 min while I went shopping for some thing for the wife (didn't find anything)... So I returned to the 328i I started it up,.. No issue so far... As before by this time I would be staring at the bright red Battery Icon on the dash wondering what is going on...

So I am home now and will let it sit again for about 2 hr. before I must go get some work done. 1:30pm