Battery Voltage Loss With Key Out

[YO7_A66]

70 Challenger:

I started up the car on a Thursday night to work on the choke and idle settings for about 15 minutes or so. Shut it off and put the key away.

Saturday morning, I open up the door to see no interior lights. I try the headlights and nothing. Grab my meter and it showed 1.8 v. The battery completely died in two days.

I am currently charging that battery to get a full charge and then I will take it in and have a load test. But until then, I grabbed a backup battery and connected the Positive cable to this battery (12.4v) and then grabbed my meter (DC Ma) and connected into the disconnected Negative cable and then to the Negative post. With nothing on and the doors shut I got .02 on the Ma setting.
I then tried the parking lights, and they read .10 (original wiring). I then tried the headlights and it read .12 (headlights on relays). I then shut off the lights and I opened one door, and it read .02.
Do any of these readings show any red flags for the battery drain?
This might just be a case of me leaving the parking lights on and putting the cover on (light outside) and being dumb.
Once I get the battery charged and checked, I will put it back in the car and start it up and watch to see if the alternator is adding anything or not.

Thanks

 

[67Dart273]

You are going to explain EXACTLY how you took all these readings, because, as posted, they make no sense

The way to find a drain is to measure as you did, except I NEVER start with an ammeter/ milliameter in the neg lead, because if there is a drain larger than the meter can measure, some meters are not well protected. Flukes are, but the fuse protection IS EXPENSIVE. You don't want to pop those fuses very often

I start with a 12V test lamp with a "real" bulb, not LED. If it lights brightly, I move to a rigged up old stop/ tail lamp socket and play using one, the other, both filaments to try to get some idea how big the draw is, or if it is "big."

Then IF you have it identified as small "enough" get your meter in there as you did in the neg cable.

THEN remove fuses one at a time until (you hope) the drain stops or gets a lot less

Be aware of "forgetful" items like glove box lamp, trunk, underhood, or even courtesy lamps

Be suspicious if the car has a "key in" lamp and the timer circuit.

Newer radios have a "keep alive" full time hot wire for the station selector memory, AND THE PA for the audio amp either separate, or in the radio, is often "hot" all the time, and they can "leak."

Other things that can leak on (especially) older cars are alternator diodes, and the radio suppression caps. There was originally one on the IVR for the gauges, and one on/ or in the alternator. The one on the coil + is dead with the key off

 

[Dana67Dart]

does your car have a trunk light?

 

[Dana67Dart]

I grabbed a backup battery and connected the Positive cable to this battery (12.4v) and then grabbed my meter (DC Ma) and connected into the disconnected Negative cable and then to the Negative post. With nothing on and the doors shut I got .02 on the Ma setting.
I then tried the parking lights, and they read .10 (original wiring). I then tried the headlights and it read .12 (headlights on relays). I then shut off the lights and I opened one door, and it read .02.

the values you are getting do not make sense. your meter might have a blown fuse or you did not switch the leads to the proper terminals. The parking lights should draw close to 1 amp each, 4 parking lights is 4 amps or 4000ma

try the test again but in the amp scale and be sure the leads are correct.

67dart273's point about the light bulb test is very valid

 

[harrisonm]

I am pretty good with automobile electrics. Not an expert like many others on this forum, but I get by. It sounds to me like @YO7_A66 is trying to track down an open circuit that is draining the battery. If you take the negative cable off the post and check for current flow between the post and the cable, there should be nothing unless a radio with a constant drain for the station memory has been installed. If there is a drain somewhere, there will be a current flow between the post and the cable. Then I would pull the fuses out one at a time until the current flow stopped. Then, at least, you will know which circuit to examine.
Also, when @Dana67Dart asked if your car had a trunk light, that is a great thought. If the trunk or glove box light switch is bad and the light is on all the time, that will drain a battery. in a completely dark garage, you can often see a little light if one of those bulbs is on. Another way is to open the trunk and immediately touching the bulb. If it is hot, that is likely the problem. A bulb won't get hot in the second it would take to touch it right after opening the trunk lid. Have fun.

 

[Bewy]

Make sure the interior light was not left in the 'on' position.

 

[YO7_A66]

Thanks everyone.
I do have an older meter and I’ll have to check the fuses. But I’ll use my test lamp on the next try.
No radio or trunk light and I’ll have to check that glove box light. My interior lights were set to off.
I should be able to test the battery this weekend.
Thanks again!

 

[ESP47]

I think Dana67Dart is probably right, did you switch your red lead over from the voltage terminal to the amps terminal on your multimeter?

 

[YO7_A66]

I think Dana67Dart is probably right, did you switch your red lead over from the voltage terminal to the amps terminal on your multimeter?

I just checked my multimeter and the answer is NO I DIDNT!!!
I’m a dumb a!!. I will redo the test again this weekend.
Thanks

 

[67Dart273]

Set up a current test that you KNOW the results, like, maybe, the dome light circuit, to make certain your current function is not damaged. Many less expensive meters are not well protected, others have a fuse in the current circuit.
I first owned a (then new) Fluke 7X series in about '93. Since then, and several more similar Flues, I've popped the (expensive) current fuse about 5 times. They are EXPENSIVE!!!

 

[YO7_A66]

I got the battery mostly charged at 12.6v and it held there for 3days sitting out of the car.
I bought a new 12v test light, and I switched my test leads on my meter to the correct position.

My battery has two top posts and two side posts.
I started out with the alternator wire hooked up to the side post on the battery and used the test light between the neg post and the neg cable. No light and it tested at .02ma dc.
Then I hooked up the body 12v cable to the top post and got the same results, no light and .02ma dc.
Then I opened up the drivers side door and had a bright test light and had a reading of 17.0.
I then shut the door and turned on the parking lights and got a bright light and a reading of 40.0.
Then turned on the main head lights (wired to relays) and got 88-89.0 and the headlights came on.
I retested the battery and its still at 12.6 v and I am leaving the cables hooked up to it and I will check the voltage tomorrow night.

So the test light was not lit with both positive cables hooked to the battery and a reading of .02-.03ma dc.
I cracked open my drivers door a little as I could and I was getting the test light to come on. So I am wondering if I left the drivers side door opened that Thursday night (I was in and out of the drivers seat a few times while it was running) and I covered up the car and did not realize that I left the door cracked.

So I will check the battery again tomorrow night and see what the reading is. If it is good then I’ll start it up and see what the alternator is charging too.

Thanks everyone!

 

[Dana67Dart]

0.02ma is 0.00002 amps

Your meter probably reads that with the leads disconnected.

88 ma is 0.088a that's not the reading you should get.

There are 3 ways to test the parasitic draw but only one will tell you that you have one.


Test light, headlights on. Test light bright, headlights dim.

Hooking a test light up and an amp meter only reads the current of the test light.
Test light bright, head light dim

(This is the ONLY way to know what draw is being pulled)
Amp meter and headlights on


Amp meter in AMP mode, leads hooked to correct terminals, fuses in the amp meter good.

Headlights bright, amp meter reading 3 to 10 amps (3000 to 10000 ma)

 

[YO7_A66]

Thank you for the info!!