[C2] Battery Draw

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May 4, 2023 | 07:38 AM

#21

thoyer

Melting Slicks

Joined: Sep 2005

Posts: 2,720

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From: Warminster PA

Quote:

Originally Posted by KRC 65VETTE

Disconnect plug in field wires load to battery goes away when measured between disconnected positive and positive battery terminal post. After reconnect of plug in load returns. Unplug voltage regulator (solid state) load goes away., reconnect and it returns.

Sounds like you found the issue - try another regulator / alternator

May 4, 2023 | 09:11 AM

#22

dplotkin

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Joined: Feb 2012

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From: Western Massachusetts

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Quote:

Originally Posted by KRC 65VETTE

Dan, sorry for delayed response was out of town a while. Long and short, no AC reading while running. Checked alternator out put and was still 13.6 to 14.2 on DC readings. Pulled alternator since its fairly easy and took to a shop to test on bench and they said diodes are bad. Using test o ohms checked good while in car but bench test showed they were bad so hopefully problem solved. Dropped both date coded 37A alternators off to get rebuilt. Fingers crossed his is the fix. Thanks for input!

20 posts, I called it at post 9. Not that I need a pat on the back but it was obvious early the trouble was in the alternator itself and a slow discharge is generally a bad diode or two. You tested them properly, they should conduct in one direction only, however they can fail as they warm up or as they confront increased current. Good for you.

An voltmeter set to AC volts across the battery engine running will show any leakage.

Dan

May 21, 2023 | 12:13 AM

#23

KRC 65VETTE

Thread Starter

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Joined: May 2021

Posts: 20

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From: Dallas

As stated by Dan there must have been a diode failure even though when testing alternator statically all tested good. Test at O'Reilly's on machine failed. Ordered date coded replacement and all good. Thanks all for help.

May 27, 2023 | 03:12 PM

#24

jiscot

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Joined: May 2007

Posts: 91

Likes: 1

From: Calgary

Thanks for all of the great advice with battery draw problems. I would really appreciated if I could have additional advice if I'm on the right track. I have a 1966 Convertible with A/C. Brand new battery died after 3 days...completely dead. It appears that I'm drawing about 3 amps with all lights off, door closed, ignition off. I pulled absolutely every fuse and 2 wires out of the fuse box one by one - nothing left in their at all. No change. Disconnected the horn relay (after market) no change. Disconnect the red wire to the alternator - no change. Unplugged the quick plug in AND the red wire on the alternator - draw is .49 Amps (with absolutely nothing installed in the fuse box). Am I on the right track ? Sorry for the ignorance - just learning still.