Battery drain issue/ .010 reading on volt meter

[72 Super]

With my volt meter between the negative battery cable and terminal I am getting a .010 reading with my meter set on 10amps

I posted this in the electrical section also. My question is, is a .010 reading norma for these trucksl? My battery does drain.

Thanks,
Ray

[72 Super]

I think my volt meter is giving me a false reading. I can turn the fan and the headlights on and I am still getting the same reading. Have to try another meter

[dmjlambert]

With most meters I have seen, when you put the selector on 10A there is also a different place to plug in the red wire on the front of the meter. Does yours have that?

[72 Super]

Here is the way it is set right now

[dmjlambert]

Black wire goes in the spot marked COM, red wire in spot marked 10A, switch goes in 10A position, probe end of black wire on negative battery post, probe end of red wire on negative battery terminal which has been disconnected from the battery. Then let's see what you got.

[dmjlambert]

And press the mode button so DC is indicated on display. I'm having a look at the manual for that meter. https://www.manualslib.com/manual/57...page=14#manual

[Steeveedee]

If you have NO aftermarket devices installed in your truck, the only thing that I can imagine draining the battery is a bad alternator diode (or a stuck horn relay, stuck tail/dome light switch, etc.). That said, an aftermarket radio or an electronic trailer brake make a draw, but my battery doesn't go dead even if I don't drive my truck for a month or more. Something as simple as dirt on top of the battery will drain it when the humidity is high. When I worked as a mechanic and people came in with a low/dead battery, and the top was filthy, I'd put a voltmeter on it and show that there was potential all across the top of the battery. Of course, I would check the battery condition and charging system, and if they were OK, I'd tell them that the problem was just the wet dust on the top of the battery. Cleaned it off and sent them on their way.

[72 Super]

Thanks for the tips guys. I am going to try another meter. This volt meter stopped giving me a reading. It now it just sitting at 0 no matter the function. It’s been along day lol.

As far as accessories go it does have an aftermarket radio and a very old style electric trailer break controller. The horn does not work nor click. I have a horn relay on order. I am going to have to alternator tested this week to eliminate that and go from there.

I will report back after I get the alternator tested.

Thanks,
Ray

[dmjlambert]

Sounds like a good plan. The meter has fuses inside.

[jocko]

Recommend use the mA setting for the voltage drop test when trying to find a battery drain - you will have more fidelity in your reading. If I recall correctly (it's been a while since I've done it ), anything >50-60 mA is a potential batt drain. Make sure everything is off (no cell chargers plugged into your cig lighter, no dome or underhood lights (if you may have added one) on. This is a catch in doing a voltage drop test in later model trucks - the underhood light is gravity triggered, so you have to detach it and let it dangle so the light isn't triggered on by opening the hood. (anyway, not applicable if your truck is stock, but mentioning just in case. If you're seeing >50-60 mA, then you can start pulling fuses to see what circuit drops the mA reading, but don't forget that opening the door turns on the dome lamp If you see >50-60 mA, THEN you can open the door to get to the fuses - but note your mA reading AFTER you open the door and use that as your ref baseline for seeing if pulling a fuse triggers a mA drop - not the reading for when everything was off. Best if you can keep everything off, incl dome lights, if possible. Can also just remove the dome light bulb if you need to keep the door open to get to the fuses. You probably know all this - just throwing it out there just in case.

[gmc684x4]

Here is a video on testing

https://m.youtube.com/watch?v=2Y8t5hIFtAk

[lil hoodlum]

I'm subscribing for other information. I had a "stuck" horn relay that was also draining a battery. I finally found that out when I touched the horn relay and it blazingly hot.

[72 Super]

Okay a little update

After sitting over a week with battery disconnected I had get 12.53 volts.

With the engine running I get 14.34

Under load 14.05
No load 14.35

[72 Super]

With another multimeter I am still coming up with 0.01 reading.

Multimeter
Black lead plugged into COM
Red lead into 5A

Black lead to neg terminal on the battery
Red lead to negative battery cable

[Big Kev-O]

In the picture your meter is set to the full Amp range and is showing .01 Amps which is 10 milliampere. This is probably the lowest value it can detect while in the Amp range setting. To get a more accurate reading you should have the dial turned to the 200m or 20m range and the lead should be plugged into port below the one you have it in.

If the 10 milliampere reading is correct you should not be having an issue with battery drain unless there is a load that you are not picking up all the time. For example, I have a brand new key switch in my truck and it will allow me to pull the key out when I am in the accessory position. When I do this it leaves the accessories powered up and slowly drains the battery. If my radio is off when I stop the truck I don't even realize that the key is in the ACC position.

Let us know what it reads when the meter is set to milliampere.

[72 Super]

Originally Posted by Big Kev-O

In the picture your meter is set to the full Amp range and is showing .01 Amps which is 10 milliampere. This is probably the lowest value it can detect while in the Amp range setting. To get a more accurate reading you should have the dial turned to the 200m or 20m range and the lead should be plugged into port below the one you have it in.

If the 10 milliampere reading is correct you should not be having an issue with battery drain unless there is a load that you are not picking up all the time. For example, I have a brand new key switch in my truck and it will allow me to pull the key out when I am in the accessory position. When I do this it leaves the accessories powered up and slowly drains the battery. If my radio is off when I stop the truck I don't even realize that the key is in the ACC position.

Let us know what it reads when the meter is set to milliampere.

I think I found the issue. I pulled the radio plug out of the fuse panel. My multimeter didn’t change. I then pulled the cig lighter plug out of the fuse panel and my meter went to 0.00. I then noticed the radio had no power. Someone spliced the radio into the cigarette lighter harness wire.

[72 Super]

Originally Posted by 72 Super

I think I found the issue. I pulled the radio plug out of the fuse panel. My multimeter didn’t change. I then pulled the cig lighter plug out of the fuse panel and my meter went to 0.00. I then noticed the radio had no power. Someone spliced the radio into the cigarette lighter harness wire.

I switched the Red lead to the middle slot. I now get 00.0 at 200m and I get 0.00 at 20m.

I then plugged the cig wire back into the fuse panel and it went to 8.2 on the 20m setting.

[RustyPile]

Originally Posted by 72 Super

I think I found the issue. I pulled the radio plug out of the fuse panel. My multimeter didn’t change. I then pulled the cig lighter plug out of the fuse panel and my meter went to 0.00. I then noticed the radio had no power. Someone spliced the radio into the cigarette lighter harness wire.

It doesn't matter what circuit is used to power the radio.. If your radio was turned off during these tests, you're reading the current draw of the radio's memory function.. Normally that draw isn't enough to run down the battery over a short period of time.. Connect the radio's power lead to the "radio" fuse in the panel.. Re-run those tests and you'll probably get the same results... If your battery is good, I suspect the radio memory is faulty and drawing more current than it should... A good test for this would be leaving the radio completely disconnect from any circuits and let the truck sit a few days with the battery connected.. If the battery holds it's charge, you'll know the radio is the source of the drain..

[72 Super]

Here is how my multimeter is set now with Black lead at Neg. battery terminal and the Red at the Neg. cable.

[body bolt]

Originally Posted by 72 Super

Here is how my multimeter is set now with Black lead at Neg. battery terminal and the Red at the Neg. cable.

If you haven't yet, you're going to blow the fuses in the meter. Lighters are typically >= 10amps. I suggest forgoing the current tests unless you have a lot of fuses. Why do you think something is draining your battery? Does the battery drain significantly over time with it disconnected? Have you tested the battery?

[dmjlambert]

If you still get 8.2 on the 20m setting with the radio/cig plugged back in, then you know you have not blown the fuse in the meter.

If that is a stock AM radio from 1972 then there is a problem with it. If it is an aftermarket digital radio, then that is how much the clock and memory draws when it's off, and that is OK. 8.2 mA is very low current draw and if you run your truck once a month you should not notice the battery getting drained.

[body bolt]

Originally Posted by 72 Super

I think I found the issue. I pulled the radio plug out of the fuse panel. My multimeter didn’t change. I then pulled the cig lighter plug out of the fuse panel and my meter went to 0.00. I then noticed the radio had no power. Someone spliced the radio into the cigarette lighter harness wire.

OK, I didn't see this. Does your truck have A/C? I had a problem where the anti-dieseling relay was constantly energized and it's on that circuit. Do you hear a click when you disconnect/connect the battery cable or insert the fuse? That relay is next to the lighter. I just unplugged the relay and left it that way.

[RustyPile]

Originally Posted by body bolt

If you haven't yet, you're going to blow the fuses in the meter. Lighters are typically >= 10amps. I suggest forgoing the current tests unless you have a lot of fuses. Why do you think something is draining your battery? Does the battery drain significantly over time with it disconnected? Have you tested the battery?

72 Super posted on the "ELECTRICAL" Forum that he installed a new battery with no changes to the symptoms.. We can assume he has a good battery, although you have a good idea..

[RustyPile]

72 Super,
I mean this with absolutely no disrespect.. Your inability to set up and read a DVM indicates you don't have the skill set to troubleshoot this problem.. Your best bet is to place your truck in the hands of a competent automotive tech who can accurately diagnose electrical issues..