BMW 3-Series E46 - 04 3.0 BMW 330 battery not charging: Motoring Technical Car/Motor Issues forum

Technical Car/Motor Issues > BMW 3-Series E46 - 04 3.0 BMW 330 battery not charging
Thread Author: legacylad	Replies: 3

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Sat 14 Nov 15 15:21

BMW 3-Series E46 - 04 3.0 BMW 330 battery not charging - legacylad

The battery warning light flickers on & off for a split second every minute or so, even when cruising at speed. My CTEK MX5 ensures it starts every morning and an electrical engineer friend who designs & builds power supply systems has checked the battery ( original from 2004) and tells me it's ok. A cranking test shows voltage of 9v which is ok, and by using a clampameter & voltmeter the alternator is doing some charging, although only 12.5v when it should be 14.3v
He thinks it may only be necessary to replace the regulator, not the alternator, which would save circaÂ£150 in parts.
He is not a mechanic per se, so would appreciate any other advice to confirm, or not, his findings. Many thanks.

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Sat 14 Nov 15 17:33

BMW 3-Series E46 - 04 3.0 BMW 330 battery not charging - bathtub tom

Been a long time since I got involved with alternator faults, but when I did I found they were three phase devices. If one phase goes down it can cause the sort of readings you're getting. The solution is the look at the output on an oscilloscope, that will soon show up many faults.

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Sat 14 Nov 15 18:28

BMW 3-Series E46 - 04 3.0 BMW 330 battery not charging - carmalade

I would not bother replacing parts of an alternator.Exchange/re-con units are available cheaply enough in the aftermarket .I would also replace the poly-vee belts while your are doing the alternator.There is a small belt that drives the a/con pump.

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Sat 14 Nov 15 21:54

BMW 3-Series E46 - 04 3.0 BMW 330 battery not charging - legacylad

Thanks guys. A pint or two of Chinook next time you are in Settle.

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