short somewhere?

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Backally

Backally

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70 Duster. I disconnect the battery when it sits. Noticed lately that there is a very small spark when I connect it back up that I did not notice previously. I am still learning electrical stuff, so not sure if I am using my Flukemeter correctly or not. I disconnected the - batt terminal and when I connect the meter probes between the batt and connector the meter starts at about 16 and rapidly works it's way to 0.5. Is this the way the meter would normally read? Without hooking up the batt, if I let it sit for a couple minutes and do it again it reads the same.
I tried to upload a video of my meter as I do this, couldn't so am trying a uTube link. It takes about 10 seconds in before I get a good connection.
Thanks
 
Yep, aftermarket radio, clock, glove box light staying on, trunk light staying on could all cause issues.
 
You can arrow it down a bit by removing one fuse at a time. When/if the issue disappears you'll know which circuit to research. Since each fuse only services a small number of items it will easier to narrow it down. If "NO" fuse makes a difference then it's probably something under the hood, then you start disconnecting things until the Volt meter give you the reading you're seeking. Treblig
 
Correct, you have something turned on and as soon as you connect the battery it wants to turn on, drawing juice. Suggested items are good, especially any modern electronic device. Is the door open when you do this? It could be your dome light.
 
Try using a test light, instead of a digital meter. Sometimes in the electrical circuits they use capacitors, for radio noise, they look just like a points condenser in most cases. You may see a spark briefly until they charge, digital meters have a hard time reading circuits such as these. Use test light between the battery post and battery clamp, if you see the light bright you know that you a draw.....
 
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Pulled all the fuses, seemed be steady draw instead of bleeding down. Doors closed, dome lights off. I do have an aftermarket radio, I pulled the fuse for that one with no change. I’ll get a test light and see what that does. Confirm for me the meter is set correctly and I’m reading it right?
 
A spark means nothing.
Amp meter inline on either cable to battery will tell you your amp draw.
If there is a stereo amplifier in car, the capicitors need to charge when its connected.

Best way to check is by first driving car, then with the aid of a disconnect on the battery post, and meter inline open the battery circuit. By doing this, the circuit does not get inturrupted, and it will give you more consistent test results.
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Note the disconnect. And probes in proper locations. Ammeter set on 10 amp dc.

Reason i use this method, is in many situations disconnecting battery will cause fault to drop out until next drive cycle.
Consistent test gives consistent results.

From here you pull fuses, disconnect circuits or pop out bulbs.
Remember, door open causes a draw,and turning on key will likely overload the meter.

And remember to return probe connectors to the proper location before testing for voltage. A common mistake made by everybody-at least once.
Happy testing.
 
Its inline between battery post and cable? You are getting a 4 amp draw? By my standards that’s huge. 300ma is average for an average fuel-injected car with all the electronics.
Thats enough to make heat. Something will be warm.
 
You might have you meter connectors plugged incorrectly, check out this video. Although it shows a Fluke 23 it's very similar to your Fluke 21. You'll have to go to near the end of the video to see how to use the connectors and meter plug ports:



Here's another helpful video:



Happy hunting!! treblig
 
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Treblig said:
You might have you meter connectors plugged incorrectly, check out this video.
Happy hunting!! treblig
Click to expand...

Well that made a difference! Hooked it up as shown in the video, showing zip. I also ran down and got a test light, doesn’t come on at all. Turned on the dome and parking lights to make sure it showed a draw and it did. Man, do I feel better, think I’m good. Was thinking the dash was coming apart this afternoon to trace wires, but instead may get out and put some miles on the old girl.
Thanks guys!
 
Backally said:
View attachment 1715239354

Well that made a difference! Hooked it up as shown in the video, showing zip. I also ran down and got a test light, doesn’t come on at all. Turned on the dome and parking lights to make sure it showed a draw and it did. Man, do I feel better, think I’m good. Was thinking the dash was coming apart this afternoon to trace wires, but instead may get out and put some miles on the old girl.
Thanks guys!
Click to expand...
Always remember.........the internet is your friend......most of the time?? The spark will always be there with an after market radio because it has a memory battery and it will draw a charge almost anytime you disconnect re-connect the battery for a while. Some stereo amp do the same thing. treblig
 
Using your voltmeter won't tell you much of anything. You need to switch it to the DC ammeter which measures current flow in amps or more likely in microamps. Disconnect one of your battery cables and put the ammeter in series (one lead to the battery and one to the battery cable.) and see what it's drawing. It should be zero or if you have an aftermarket radio it may be drawing microamps of current just to keep the RAM on the radio alive. If it's drawing quite a bit isolate the circuit by pulling fuses as stated above. I once found I had a current draw due to a glove box light not turning off in which case it was drawing milliamps of current and would drain the battery in 2 days.
 
Check your trunk light. On my dart I kept getting dead batteries I replaced everything and never could seem to fix it I finally put a toggle on the battery and turned it off every night. Well one day when I got home from work I opened the trunk and reached in and the light burned my arm. I was like wth how did it get that hot that quick? Then I dawned on me. That is what was killing my battery. I took out the bulb and problem solved! Never had to use the battery toggle again. I never did replace the switch. I may do it now that I'm "restoring" it.
 
Growing up a poor boy back in the day I always used a test light as mentioned above. Didn’t have a meter. It was a dash light sized bulb with a couple of feet of wire and alligator clips. I still do it today. Digital meters can fool you sometimes if you are not used to them.

I would take off a battery clamp, hook one lead of the lamp to the battery cable and the other to the empty battery terminal. If the lamp lights up, you have a current draw. If the lamp lit up, I would touch the battery cable back to the battery for a second or two. This would charge up the radio or delayed dome light or what ever else might draw current temporarily. If the light went out after that, everything was ok. If not, more troubleshooting.

Newer cars with a lot of electronics may take a substantial current to charge everything up in initially.

As I recall, some aftermarket radios and alternators with built in regulators will draw a small current all the time, on the order of micro amps, but this will not light a dash light sized bulb or drain your battery in less than about a month.

This is just one technique for troubleshooting, may not work in every situation.
 
Backally said:
View attachment 1715239354

Well that made a difference! Hooked it up as shown in the video, showing zip. I also ran down and got a test light, doesn’t come on at all. Turned on the dome and parking lights to make sure it showed a draw and it did. Man, do I feel better, think I’m good. Was thinking the dash was coming apart this afternoon to trace wires, but instead may get out and put some miles on the old girl.
Thanks guys!
Click to expand...

CAVEAT!!!!

Be VERY careful measuring current. You last photo is correct, BUT read on!!!

If you are attempting to measure an unknown current, DO NOT hook the multimeter up FIRST. This is because if the amp draw is MORE than the 10A circuit in the meter can handle, it will blow the (expensive) fuse in the Fluke, and if you have the probes in the lesser current "hole" it will DARN sure blow that fuse

What to do?? easy:

Obtain a "heavy" wattage lamp for a test lamp. An old stop/ tail socket with an 1157 works great, because you can wire it different ways for less or more current

So when measuring an unknown short do this:

As you did here with the meter put the bulb in series with battery ground.

For heaviest to lightest draw:

HEAVY:

Twist the two stop/tail wires together and use that for one terminal
Use the bulb shell for the other terminal

Somewhat less wattage:

Use the wire for the heavy filament, the stop/ turn one, and use the bulb shell for the second terminal

Less wattage yet:

Use the tail wire and the bulb shell

Lightest

Leave the bulb shell disconnected/ isolated, and use one wire for one terminal and the other wire for the remaining. This puts the two filaments in series.

This little doo-dad is GREAT for shorts. You can wire the bulb in, and if the short is present, it won't burn fuses or burn wiring. All it will do is light the lamp

WHY DO YOU want to use this BEFORE your meter: Because if you have a HEAVY draw, more than the meter can measure (10A in this case) you will not blow the Fluke meter fuse. THESE ARE EXPENSIVE

 
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