Novice alternator question

[Blueskyflying]

I’m probably going to need to replace my alternator (bat light on in dash) but iv noticed in may post that the voltage regulator was the culprit in may situations.

Iv looked up the part from real OEM but was wondering this:

If I replace the alternator part number 12317508054 dose that include the voltage regulator part number 12-31-1-713-491-M14?

Are these two totally separate things or is the voltage regulator part of the alternator?

Thanks

[CharlieHustleX5]

The voltage regulator is a part of the alternator, but can be purchased seperately from the alternaotor itself. I purchased a new alternator when my battery light came on. I thought it was sort of odd considering I only had 61K miles on my 04 x5 3.0i when this happened.

I purchased a new voltage regulator for the Valeo 140A alternator I had, swapped it out for kicks one weekend, and what do ya know....No battery light and still kicking strong since. Sure, I'm stuck with a fairly new alternator sitting in the garage, but it'll come in handy in case I happen to be wrong and something else was wrong with the alternator I just fixed. Most of the people I spoke to regarding the BMW alternator had mentioned that the most common thing that goes out on the alternator is the voltage regulator.

[Blueskyflying]

Thanks for posting a reply to my question. Hopefully there is a good DIY out there and I can try to save some cash.

Thanks again!

[TerminatorX5]

Hey guys, sorry for reviving the old thread - I've got a red battery light and trying to see if I can get away with minimal blood as possible...

the part number that the Blues Sky mentioned for the alternator is the one that would fit in '02 E53 4.6iS, and it is confirmed by the RealOEM... the regulator part is not coming on the RealOEM as part of the 150Amp alternator... Is it so important I should not worry about it?...

Any ideas?

[Weasel]

That's because you have the water-cooled alternator, the regulator is not separately replaceable as it is epoxied into the front face of it. The internal design of that alternator is actually pretty different than the regular 120 amp unit in most other BMW's.

[TerminatorX5]

Weasel, I just saw this reply and it makes my question in the other thread completely dumb...

So, I am in for a whole alternator replacement...

Before I venture out and get one, any other thoughts about what else could have caused a red battery light - seems that the power steering is ok, no other lights are on, so, possibly the water pump is still running... So, the belt might be ok...

voltmeter shows 12.26 volts with cold engine in the morning, the car starts right up, the meter shows 11.25V, so there is no charging juice in the circuitry... This is not a load tester, this is just regular RMS meter.

I have two little solar panels fitted to the car in order to keep the battery topped off when I am not in town and the car is just parked with the doors locked and alarmed. The solar panels have been in that car for almost 3 years, no problems...

As I looked into engine bay, I could not see alternator, and was barely able to see the belt itself...

So... the verdict... alternator?

[Weasel]

Yep... thats gonna be the alternator. Unfortunately this happens to be one of the more difficult ones from BMW. It is at the bottom on the drivers side. It is a bitch to remove because you not only have to remove the fan w/shroud, but there is an idler pulley bolted to the alternator housing from behind that is in front of one of the alternator mounting bolts and is a pain to get off without swivel sockets and flex wrenches. And not to mention that since it's a water cooled alternator, you lose the engines coolant as soon as you pull it so have a big drain pan and some fresh coolant handy. Thinking about it, I don't see it being done without a rack to lift the vehicle.

[TerminatorX5]

So... since it seems to be the alternator without a doubt, I wonder if there was anything that I have done to cause this problem - because if I am the culprit, then the new alternator will go up in smoke in no time...

What could bring an alternator down to its knees? an electrical overload? is it protected by a fuse or a "breaker"? Is there a home solution to see what the load is?

I know that there are codes in the high and low cluster that allow you to see the tachometer in digital output, gasoline quantity in liters, some other cute things along with voltage output directly on the computer readout in the cluster... There are many posts on how to access this information... I just do not recall, if any of those readouts provide the amperage of the load on the system... Knowing Germans, I would suspect that they probably have it built in somewhere, don't you think?

[Weasel]

The load on the system varies fully depending on what is on.. like headlights, seat heaters, ac blower speed etc. Your X5 has a few years on it, and the alternator likely just got old. BMW's have a high electrical demand due to all the extra shit that makes it a BMW, and have BIG alternators to compensate, whose output is controlled by the DME. As good of alternators as BMW builds, the components aren't indestructable... and will still wear over time.

The biggest thing that shortens the life of the alternator and battery is the system voltage not being properly maintained, usualy from short trips with high load.

[mrbmwx5]

Originally Posted by weasel56

The load on the system varies fully depending on what is on.. like headlights, seat heaters, ac blower speed etc. Your X5 has a few years on it, and the alternator likely just got old. BMW's have a high electrical demand due to all the extra shit that makes it a BMW, and have BIG alternators to compensate, whose output is controlled by the DME. As good of alternators as BMW builds, the components aren't indestructable... and will still wear over time.





The biggest thing that shortens the life of the alternator and battery is the system voltage not being properly maintained, usualy from short trips with high load.