Alternator producing AC current?

sewerman · 4th April 2021, 10:19

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

4th April 2021, 10:19	#1
sewerman Gets stuck in MG ZT+ CDTi Join Date: Feb 2014 Location: Wolverhampton Posts: 632 Thanks: 166 Thanked 264 Times in 154 Posts	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