Special Delivery
Junior Member
I’d agree with you all. This was my dad’s and he made some changes so I am running with his past decisions. Crossing my fingers and hoping a new alternator will solve my headaches.
Parasitic Drain?
- Thread starter Youngblood
- Start date
Bob Bidonde
Well-known member
Jim M
Senior Member
I think everyone has this problem. I bought a cut out switch from NAPA and installed it just under the fire wall on the positive battery cable. When I shut the A down I turn that switch off and now there is NO juice flowing in the car while it is parked in the garage. Works like a charm. Never have a battery issue.
Kurt in NJ
Well-known member
Stock cars with generator don’t have the parasitic drain, I can let my car sit 6-8 months, no maintainer charging in between and I expect it to start,
Benson, had this happen on a customer car today. Drain on battery and started looking and got out my meter in series and discovered draw was .667 Amps which was the 30/31 dash light. Turned it off problem solved. His battery voltage was so low that even when lamp was on the light wasn’t visible and I only saw the car in daylight.
Easy to find issues if you know how to use your voltmeter. I have given Marc seminars several times entitled “ voltmeter “ best tool in your toolbox. I had a Full house both times…. I know this is an old thread but I always enjoyed Tom Wesenberg’s Model A friendship and wisdom and it’s great to read his comments still.
Larry Shepard
Easy to find issues if you know how to use your voltmeter. I have given Marc seminars several times entitled “ voltmeter “ best tool in your toolbox. I had a Full house both times…. I know this is an old thread but I always enjoyed Tom Wesenberg’s Model A friendship and wisdom and it’s great to read his comments still.
Larry Shepard
Yes Larry,
As soon as I saw that the drain was around 0.6 amps a light went off in my head for me.
I looked up the current draw on the #63 light bulb which is why my post reads #63 lamp .63 amps.
Yes, Tom was an old time Army trained Tech as I remember.
I think that he repaired "Deuce and a Half's" at Ft Bliss, TX about the time that I was there.
Last week the new battery on the 1988 Cressida went dead.
A VOM showed .95 amps drain after battery was charged ... The switch on the Map Light above the driver's seat was on. This car sits for weeks at a time sometimes without being driven.
As soon as I saw that the drain was around 0.6 amps a light went off in my head for me.
I looked up the current draw on the #63 light bulb which is why my post reads #63 lamp .63 amps.
Yes, Tom was an old time Army trained Tech as I remember.
I think that he repaired "Deuce and a Half's" at Ft Bliss, TX about the time that I was there.
Last week the new battery on the 1988 Cressida went dead.
A VOM showed .95 amps drain after battery was charged ... The switch on the Map Light above the driver's seat was on. This car sits for weeks at a time sometimes without being driven.
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I would agree. That diode will have a very small leak (draw) even when brand new. When it goes you will see a big draw.
Y-Blockhead
Well-known member
Considering a 10si alternator has 6 diodes in the rectifier, there is no doubt it will have a small amount of leakage.
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Flathead
Well-known member
Back in the dark ages it was common to use a test light, disconnect the battery cable and hook the light between the battery post and the cable, if the light comes on you have a draw that is excessive, if the light does not come on you are OK in draw department. Of course the first step when using a test light is to be sure it works.
Bill G
Well-known member
The Nu-Rex alternator I have is basically a 10si, but probably made in China or somewhere else. It's parasitic draw is so slight, I have left the car with the shut-off switch on for weeks and not had a problem. I usually turn it off when parked overnight, but I have been known to forget, just like everyone else. The main reason I have for shutting it down is just because you never know when a diode is going to fail. That being said, I never bother shutting off the shut-off switch if I am just parking for short times.
