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Parasitic draw test


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#1 football_coach

 
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Posted 27 November 2017 - 10:00 PM

2003 Lincoln LS. I'm to do a PDT to try to find what is draining my battery. I'm going to charge the battery fully either with a charger or by driving it. I'll test the battery to be sure it's charged but my question is, how long does this car have to sit before it "goes to sleep"? I don't want to get any false readings on my multimeter. As always, thanks for your professional, and spot-on, advise.

#2 Karrpilot

 
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Posted 28 November 2017 - 07:50 AM

Usually 1/2 hour to 45 minutes. Than no more than 50 mili amps is the Ford specification.

Although we try to get ours in the fleet down around 35 if we can.

Some of our vehicles that sit a lot, we wire in solar powered battery trickle chargers.

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#3 football_coach

 
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Posted 28 November 2017 - 06:40 PM

I have a charger that will provide a trickle charge but I'm still gonna try to find the source of the leak. But I may not get a chance until Saturday.

#4 Mike N

 
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Posted 28 November 2017 - 09:03 PM

Bill - how long does it take for your battery to drain down?

 

Beyond that, are there any aftermarket devices in the car, like a remote start or stereo? That's usually the first place I see draw issues.


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#5 Karrpilot

 
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Posted 28 November 2017 - 09:21 PM

Yes, anything aftermarket can and WILL cause issues. We see it on a daily basis with our fleet vehicles. Even something as simple as a cell phone charger left installed in a cigar lighter can do this. Not because it draws all that much power, but because it fools the battery saver relays, and keeps them from going to sleep. That in turn will power up a module when it shouldn't be.

 

And of course, battery saver relays have been known to stick. Or any other relay / module, CD changer, radio, door switches, etc.

 

Those are the types of repairs that will drive you nuts, and give you a reason to shop at your local liquor store.......


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#6 football_coach

 
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Posted 29 November 2017 - 11:29 PM

The battery is dead late afternoon of the next day. If I start it in the morning it will start although it almost didn't start a couple days ago. I've had a trickle charge on last night and tonight. I won't have a chance to do the test until Friday or Saturday and I need to be sure it starts in the morning with no time to jump it.
I do have a dash cam but, suspecting it might be the cause, I disconnected it from the power source but the wire is still connected to the fuse. That didn't help.
I did have a cell phone charger connected but I saw the light on tonight and disconnected it. But it hasn't always been connected. Thanks for the help. I'll let you know what I find out in a couple of days.

#7 Mike N

 
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Posted 01 December 2017 - 02:17 PM

Bill - How old is the battery? I chased my tail on a Grand Cherokee a year ago only to find out the battery itself was junk. I had charged it, disconnected both cables from the vehicle and the next day the battery was dead..... it had discharged itself.

 

Assuming the battery is newish, that's a considerable draw to take the battery down that quickly.

 

I'll imagine you checked that the trunk, glove box and other interior lights are shutting off? Also if you have lighted mirrors in the sun visors, make sure they're off?


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#8 football_coach

 
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Posted 01 December 2017 - 04:08 PM

I bought a battery recently thinking it was bad since it kept dying overnight. $100+ wasted; it wasn't the battery. Alternator was checked twice. Trunk and glove box lights are disconnected. Visors lights shut off. I have a lot going on tomorrow but I hope to do the PDT then.

#9 football_coach

 
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Posted 01 December 2017 - 08:03 PM

The battery (Interstate) is new. Alternator is good. I disconnected the trunk light and glove box light (just because). Visor mirror light goes off on sides. I'll be busy tomorrow but I hope to have time to do the PDT.

#10 football_coach

 
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Posted 01 December 2017 - 08:07 PM

Visor mirror lights go off on both sidws.

#11 football_coach

 
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Posted 02 December 2017 - 12:07 PM

When I do this test I need to check the inside fuse box. I need to know how to turn off the interior lights when the door is open to get an accurate reading on the multimeter. The door needs to stay open so I can get to the fuse box. I looked all around the door, and on the inside, but could not find a switch. I guess removing bulbs is an option but there has to be a better way. Thanks.

#12 Karrpilot

 
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Posted 02 December 2017 - 01:44 PM

The door ajar switch is in the door latch. However, the switch is timed to the battery saver relay. After X amount of time, the lights should go out.

Provided this isn't the issue or source of your problem.......

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#13 football_coach

 
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Posted 02 December 2017 - 08:29 PM

Well, I didn't get to it today. . .maybe Monday.


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