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Old 02-28-2018, 11:25 AM
bugbyte bugbyte is offline
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Join Date: Jul 2012
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Quote:
Originally Posted by andrewwynn View Post
Not sure how I missed this but the alternator should hold Rick steady voltage any load and any speed. The biggest instant load you can apply is probably the rear defrost with seat heaters.

If you are able to get sub 13v at idle not moving measure the vDrop from engine to chassis and see if you can measure any voltage drop on the ground.

Then using OBD measure the vBat and see if you can get it to hiccup with a throttle off with heavy load (wipers and defrost/seat should do it) if you can get a voltage drop of more than 0.4-0.5v from that test the voltage regulator is not doing its job.

I've recently removed and replaced an alternator on an M62 very similar it was way easier than the air cooled one on my M54 other than the annoyance of course of having to drain the coolant. Either case have to remove the fan.

I've never taken apart the water cooled models to figure out what it takes to replace the brushes and slip rings but it saved me almost $300 to refurbish mine vs replace it
I will do another load test with heated seats on and rear defroster. For some reason when I did the load test before I didn't think of the heated seat and the rear defroster. I have the re-manufacture alternator sitting on the shelve ready when I am sure that the alternator can't handle the load. I would said if all the load is on it should be getting around 13.5 V or more. If not the battery will never get enough charge.
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2003 X5 4.4i w/ Sport Pkg, Cold Weather Pkg.
2010 X5 4.8i w/ Sport Pkg at 19,000 miles
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