Voltage Regulator?

[My1stBMW]

So, early this Saturday morning on my way home driving on the N1 the dashboard battery light comes on. There were no signs of power loss nor lights dimming as has been described in some forums (beams were on as it was still dark). Drove all the way home fine with no issues but the light stayed on all the way. Parked the car and went to bed.

Later today, after having breakfast at around 12:30, I decide to investigate. So got out the old volt meter and checked the voltage on the battery, which was at around 12.2v so no problem with the battery. Started the car and the voltage drop to around 11.8v. I confirmed these figures using both the volt meter on the battery and the OBC menu 9. As i switched on additional items (ac, radio, lights), with the car running, the voltage continued to drop. At this point, I sort of concluded that the alternator is gone as there was clearly no charge at the battery. Locked the car and went to do some reading on forums.

After reading through as many threads as possible, I sort of concluded that it could be the voltage regulator or the fact the the alternator should just be replaced considering the effort anyway.

So decided to pull the car into the garage and deal with it during the weak. In doing so I obviously bring up menu 9 on the OBC and all of a sudden the alternator is now charging at around 14.0v but the battery light is still on. So I pull the car into the garage, turn the car off and restart it. The battery light turned of for a few seconds this time but now the alternator was over charging when the revs climbed. At idle it would stay around 14.7v but as I rev the engine, it would climb to as high as 17.7v. Also, the warning lights on the dashboard would also come on as i climbed through the revs including the radio switching of. So i decided to let the car idle for a while and then as the engine warmed up i noticed that even at idle speed the alternator was now charging at around 15v. at this point i decided to turn everything of as I didn't want to fry any of the electrics in the car. You never know I confirmed these reading again using the volt meter directly on the battery.

So to conclude, I think is comfortable to say that the voltage regulator has seen better days as clearly the alternator has no problems charging. I'm not sure which model alternator is installed as I have not had a chance to get my hands dirty but this is a job I would like to tackle myself but am afraid that I go out and buy a VR and it turns of the alternator is gone or something worse.

Please let me know your thoughts. I hope I have added enough detail but if not please ask away.

Car details: 2004 e46 320i exclusive with just over 125k. The only extras are the xenon lights package. Bought this car from a colleague with just over 95k over a year ago and must say, being my first BMW, I am enjoy the car. So far had to replace power steering pump, which I ended up doing myself as it happened in the first week of this year and I couldn't find a decent mechanic (That I can Trust) that was open and I was defiantly not going to pay the dealers. Also, about three months ago, i decided to only fill up with BP 95 and a few weeks later my fuel gauge stopped working (It would pretty much stay stuck at full tank all the time). Not sure if it's was coincidence, but over time it seems to have sorted itself out. At the time I was tempted to reset the cluster.

 

[Charlie Brown]

Yip common problem with these, you will need to figure out what alternator you have. If its a Bosch then great. buy a new reg and off you a go. If it's a valeo, well now the fun really starts. Some are serviceable and some not, only proper Auto Elecs can tell as far as I know.

Mine on 330i had similar issue, and in the bought new one - R4000 later, damn Valeo !

 

[Ralf*]

hello and welcome to BMWFanatics,

by the description of what you have done, you are intelligent enough to have answered your own question.

I must commend you on a well laid out fault analysis esspecially for a first post at that.:bravo::bravo:raise:raise:

I woudn't have been able to do any more than what you have already done and noted.

Being a 2004 model, "motorplan" is no longer an option to worry about, so take it to the closest and best autoelectrician, or if you feel DIY enough, just source the correct voltage regulator and change it yourself, being vigilant that you replace it with the correct type of regulator and afterwards do the same meticulous checks that you have already done in your fault analysis posted above.

once again

a well laid out post of your fault analysis and nice "first" post.

keep us informed on what you do to sort this problem.

 

[Kish2604]

Replacing the alternator is in easy task if you have a manual with an electric fan, first get yours out and check which brand you have...chances are its Valeo..

If its economical I may be able to get you an alternator...drop me a pm..

 

[Iceman007]

Its the Regulator. Remove alternator and replace regulator on the alternator.

 

[zaleonardz]

+1 on everything

When altenator is on, you should expect about 13.2 to 13.6v in a car that's running correctly.

I think the reason why the batterly light was on is because the voltage was out of this range.

Careful of over-voltage, DME goes poof, so do you

 

[SP33DYV]

It is quite easy to get to the alternator. Remove the airbox and you'll see the alternator below the airbox. Remove all belts connected to the alternator and remove it. If you're lucky, it's a Bosch, if not, it's a Valeo. Replace the regulator and refit. The regulator is quite expensive, I must warn you.

 

[My1stBMW]

Thank you all for the comments. I finally got some time this afternoon to remove the airbox and try and identify what make of alternator is installed in my car. I must be lucky cause I it's a bosch. :rollsmile:



I am going to get the battery checked as the battery has drained to below 10v and therefore I was not able to start the car this afternoon. Interestingly, the battery seems to be the original battery that came from the factory. Also, the battery has it's on status checker, and according to the checker the battery is still fine just undercharged. Not sure if I can trust it.

So, hopefully tomorrow I will get a chance to have the battery tested and start getting prices on a new regulator.

Will keep you posted.

 

[Charlie Brown]

You lucky devil, yes make 100% sure you have a healthy battery and then re-check the entire system. On the original battery, not uncommon to see the proper OEM ones last 8+ years.

If you a need replacement battery I'd suggest a Varta, same / similar to the OEM you have currently.

 

[Prev]

You are damn lucky it's a Bosch unit. Valeo regulator was R1750 from the stealers last year :nonono::argh:

 

[Charlie Brown]

About R2350 now, thats why I choose to replaced the whole unit rather with a brandnew Valeo one from Diesel Electric at R3800.

The rectifyer is damaged over time by little stones etc from the coolig duct.

Wonder if the regulator is availble from DE and if so how much.

 

[Prev]

About R2350 now, thats why I choose to replaced the whole unit rather with a brandnew Valeo one from Diesel Electric at R3800.

The rectifyer is damaged over time by little stones etc from the coolig duct.

Wonder if the regulator is availble from DE and if so how much.

I also replaced mine with a Bosch unit from DE. Stock of the Valeo regulators is a problem.

 

[Iceman007]

SPARXXX SELL THEM THATS WHERE I got my original bosch regulator for a fraction of the price for R450 2years back www.sparxx.co.za give them a call

 

[P1000]

SPARXXX SELL THEM THATS WHERE I got my original bosch regulator for a fraction of the price for R450 2years back www.sparxx.co.za give them a call

They sell the Valeo as well, and have great service.

 

[Funky Toyz]

If you need a bit of a guide line, check my post in the DIY section on changing the regulator. I tried going into as much detail as possible with pics, explanations and part numbers. This was on an E90 though so only different thing should be, well nothing really if you have the N46 motor. Beware though, I could not find a regulator for a Bosch unit seperate anywhere...not even from Diesel Electric. I did get a 2nd hand part though after I spoke very very nicely to the sales guys at mech 1 who under normal circumstances, do not sell the unit seperately. I ended buying a new Bosch alternator from Diesel Electric after the 2nd regulator also failed because of the oil leak I had. Hope you get sorted soon buddy.

 

[Iceman007]

If you need a bit of a guide line, check my post in the DIY section on changing the regulator. I tried going into as much detail as possible with pics, explanations and part numbers. This was on an E90 though so only different thing should be, well nothing really if you have the N46 motor. Beware though, I could not find a regulator for a Bosch unit seperate anywhere...not even from Diesel Electric. I did get a 2nd hand part though after I spoke very very nicely to the sales guys at mech 1 who under normal circumstances, do not sell the unit seperately. I ended buying a new Bosch alternator from Diesel Electric after the 2nd regulator also failed because of the oil leak I had. Hope you get sorted soon buddy.

On my E46 325i the New Regulater had a differant part number and looked the same and was for a 120A Alternator. The reason the partnumber was diffarent is because it was aparrently an upgraded regulator. it worked fine for years and the second owner is still going with that regulator :thumbs:

 

[My1stBMW]

So, finally got a chance to source the voltage regulator and get the battery tested. wrt to the battery, according to the specialist the battery can only hold 11.8v at the moment and therefore I should probably change it. I will see how it goes. It's still the original battery, which has lasted 9 years. I really cant believe it. The specialist said the reason why these batteries last so long is two fold:

• The original batteries don't use recycled materials and therefore better quality
• Because the battery is stored in the boot, the battery temperature is more consistant than cars that have the batteries installed near the engine and therefore are never subject to the harsh engine temperatures.

The voltage regulator I got from Diesel Electric in Pretoria West. Part number was different as Bosch have change the numbers. Installed the new regulator this afternoon/evening and it's all working 100%. I'm getting a solid 14.2v with the lights on. :rollsmile:

But let me tell you this was no easy exercise. Firstly, always make sure that you have the necessary tools before embarking on your journey. I learnt the hard way today. Then when I need to get the belts of, the bolt on the tensioner decided to strip itself :=):. I had to resort to using the ax method. If you don't know what I'm talking about, google it. It's not the best method but it worked. Getting the belts back on was another mission but after around an hour I somehow managed. Anyway, I guess I will get the tensioner replaced at the next service or when I have time and patience to sort it our myself.

For those that are interested, below are some prices on voltage regulators for the bosch alternator for e46 that I managed to get:

• Bemo - R 750 (not sure if it's original)
• Diesel Electric - R 1 300 (This is the one I went with but I managed to get it for R 800)
• Goldwagen - R 500 (Can't remember the brand but definetly not Bosch)

Anyway, thanks all for the help and comments. Appreciate it. I would have taken picture during the process but I was more concerned to not break something seeing as it was the first time I removed an alternator out of a car.

 

[SP33DYV]

:thumbs:
Well done.

 

[Ralf*]

glad its sorted.....:thumbs::thumbs:

now don't go away

how about an introductory, and some pics, and some "kak" praat

 

[My1stBMW]

My battery seems to be holding out considering the agent suggested that I replace it. This morning it had a solid charge of 12.5v. Very interesting. Lets see how much longer the original battery can last. And all considering that I only spent about an hour driving around last night to charge the battery.