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Old 01-05-2019, 10:15 PM
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andrewwynn andrewwynn is offline
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alternator question

There are a bunch of modules that have voltage.


The last pic most interesting: the two dips to 13.0 happened exactly when I switched from throttle on to coasting. First when stopping to turn out of a parking lot, second to park at a curb

Notice that in normal driving the voltage stays within 0.2 v min to max. The voktage regulator changes the field voltage of the alternator to change the output voltage of the alternator, this way it can make maintain steady output voltage no matter what the rpm.

The alternator makes 3 phase AC at I'm guessing 100-400 Hz never measured but I think I've heard it. That voltage is converted to DC by a 3 phase bridge rectifier built into the voltage regulator.

The voltage regulator increases the voltage hence current to the armature of the alternator any time the output voltage is lower than desired output.

The only reason for the dips is some built in lag to smooth out the controller so Its not wandering around all the time.

When you drop throttle and it normally drops to 13, when the slip rings are worn the field current will get weaker than needed to maintain output and you will get a drop low enough to trip codes.
E53 / M54 2001 3.0i gas LHD (pair of them: his & her)

Last edited by andrewwynn; 01-05-2019 at 10:35 PM.
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