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Voltage Regulator draining battery
m4co - June 3rd, 2018 at 12:42 PM

Hi all,

The battery in my Beetle has been getting flat over the last few weeks. I found I have a parasitic draw of 90ma at the battery.

I disconnected all of my fuses and the draw was still there, I unplugged the power to the voltage regulator and the draw went away.

I tried unplugging everything off the voltage regulator one by one to see if it will go away, but it didn't. It still had a draw with only the power connected to it and nothing else, once power removed the draw went away.

Now is there a way to confirm with a multi-meter that the regulator is bad?

Fuses removed and everything unplugged from regulator (still at 90ma)

https://preview.ibb.co/cQLeXd/20180603_112027.jpg

https://preview.ibb.co/gWOYsd/20180603_112034.jpg

https://preview.ibb.co/jYLk5y/20180603_111957_HDR.jpg

The regulator

https://preview.ibb.co/gOfwCd/20180603_113441.jpg

The back is all epoxy potted and I don't think it's repairable?


pv370 - June 3rd, 2018 at 05:14 PM

looking at your diagnosis you are spot on...
maybe go an old school mechanical regulator instead of the electronic one...
im guessing there could be some electronic part in there that is connected all the time thus current drain...??????
you need to get someone else with an electronic regulator to do the same and remove all wires except the battery wire B+ from their regulator and do a current test


ACE76 - June 8th, 2018 at 05:12 PM

Maybe not Spot-On with your measurement though!
The Black plug ALWAYS goes in the Bottom socket ("COM"). The Red plug USUALLY goes in the Middle socket. You should then get a reliable reading using the 20mA DC scale that the Knob is set to... But if there is a big drain, you'll "blow" your meter!

So start with the knob set to 10A DC - 2 clicks down on Knob - and the black plug now in the Bottom socket, where it should be. If the measurement is below 200mA, you can THEN use the lower range scale.

[That top socket -- where your red plug is -- is for 10A DC readings ONLY.]

{And your reading would be 0.90mA, not 90mA -- if it was correct with knob on 20mA scale... OR 0.90A = 900mA, on the 10A scale}


pv370 - June 9th, 2018 at 11:45 AM

your correct ace76.
i didnt take a great deal of notice where the leads were plugged in or the selector. should have clicked on the pic.
it would take a very long time for 0.9mA to flatten a fully charged battery.
and thats probably the amount of current drain from whatever is connected internally across the electronic regulator.

follow ace76 advise and start your readings again.
let us know what you come up with.......................