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Old 4th April 2021, 10:19   #1
sewerman
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Default Alternator producing AC current?

Ok so I'm off next week and am going to see if I can trace why the ZT battery goes flat after 2 weeks

Doing some initial checks battery at 12.1v starts the car and DC voltage across the battery with engine running is 13.9-14.1v , but on AC it goes from 2.0v to 0.5v every second or so.

If tested 3 other cars and they all give a very low 0.4 v ish steady AC reading.

So is that a sign the regulator is failing and allowing the battery to drain or worse the alternator needs replacing.

I'd rather sort this before I go testing circuits current drain.

Thanks Scott
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Old 4th April 2021, 10:47   #2
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With your multimeter set to diode function you should only get a reading with the leads one way round between the B+ post and the alternator casing, if you get a reading both ways round your diode pack is at fault and the alternator will drain the battery when the engine is not running.
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Old 4th April 2021, 11:04   #3
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i have had an alternator throwing out AC - new alternator was required.
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Old 4th April 2021, 12:38   #4
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Thanks for the replies I'll try the diode test tomorrow when i get time

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Old 4th April 2021, 17:02   #5
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Agreed. It's those pesky diodes that are flattening your battery.---
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Old 4th April 2021, 17:22   #6
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Thanks think I'll have a look at whether it 2 or 3 wire and get a regulator from DMGRs when I order yet more front drop links.

Easier to try than new alternator.



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Old 4th April 2021, 18:48   #7
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I don't think the diodes are part of the regulator. My understanding is they are part of the rectifier.
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Old 4th April 2021, 19:04   #8
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Mmm that's in the alternator itself right so basically new alternator??? Though the regulator had diodes too??

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Old 5th April 2021, 11:47   #9
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Might be of some help.
https://www.the75andztclub.co.uk/for...d.php?t=312171
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Old 5th April 2021, 13:06   #10
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Quote:
Originally Posted by Atlan View Post
Thanks but just checked and mines a 2 pin

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