Not enough to turn a test light on. That's substantial. Something is stuck on.

Dang it me too. I try to read everything but once in awhile

Read my earlier reply

The clip on direct current measuring coils are very handy for tracing “sneak currents” in wires without cutting or disconnecting the wire.

These are called “Hall Effect” current sensors..
They used to cost $100 to $200 but have come down greatly in price.

https://www.fluke.com/en-us/learn/blog/clamps/inside-hall-effect-clamp-meters

https://www.amazon.com/BSIDE-ACM91-...Y2tSZWRpcmVjdCZkb05vdExvZ0NsaWNrPXRydWU=

I've had aftermarket voltmeter gauges drain a battery also. If it has an aftermarket one, I'd check that.

[quote=demon]Working on a 78 Chrysler LeBaron. It's a low mileage car, absolutely stock and untouched, other than it has had an electronic ignition conversion to eliminate the Lean burn system.
So the issue is:
The battery will go dead in a day or so.

Brand new battery.


I pulled off the negative cable, and put a test light between the negative battery post, and the negative cable. The test light is bright.


You can't check voltage drain like that. The minute you put the leads on the post and cable it completed the circuit through the light bulb. It'll read 12 volts too if you use a meter hooked up that way. You need to check for amps.

Voltage gauges should always be hooked up to a switched source as they draw a current through the gauge to read the V.

One of the youtube channels I watch occasionally, ScannerDanner, he had what he called a cheat for something like this: a temperature camera. He was looking for an electrical issue in a late 70s ramcharger. The only drawback to check things this way is the component would have to be visible.

I disagree, in a non automotive situation try to get a bulb to light when its connected negative to negative.

In the case above think of the bulb as acting like an amp meter as it will illuminate as a current flows through it. It is connecting to positive though the device that is using the current.

Well as a union electrician I can tell you are mistaken. It is not going negative to negative. The positive cable is still hooked up. All you're doing is taking off the negative cable and hooking it back up with a light bulb in it. The bulb itself is load. Unless you unhook every harness off the battery it will light the bulb.

If you don't believe me go out to the garage an disconnect your negative cable and then get out a volt meter and put 1 end on the battery and the other on the disconnected cable. The meter will read 12 volts.

Wrong.

A bulb will show the "load"(resistance in the system that is draining the battery) but it's not going to tell you what the load is in millivolts. You need a meter to see what that is!

Hope this helps. Its step by step.

https://www.wikihow.com/Find-a-Parasitic-Battery-Drain

Of course you can. Inserting the light bulb between the battery and the cable completes nothing. It simply extended the cable. There still has to be a completed circuit between the two battery cables to light the bulb and that's what you are looking for, what is completing the circuit. As to volts vs. current, a voltmeter/test lamp/light bulb will show that there is a drain but you do need an ammeter to determine the magnitude of the drain.

AH, Moparts strikes again! It happens with nearly every question concerning an electrical problem.

We have competing experts saying the other guy is wrong and his testing methods won't work, but mine will.

Is there any wonder why non-electrical people are confused about electrical problems? I've done a lot of automotive electrical repairs, but you guys can confuse me.

The experts argue with each other on how its suppose to be tested and figured out, and all the guy wants to to solve his problem. Who is he suppose to believe?

How about, if YOU have actually SOLVED the particular problem on a similar car the OP has, write a step by step process. If you personally have not solved the problem, don't post. This should not be a location to test theory.

I saw the reply's from some people I respect on here and decided I needed to do more research. I'm always willing to listen and learn and I learned something new today.

Since 99.9% of my work is AC I needed to do some checking. Here's what I found was causing the difference of opinion.

Answer a DC test light is a tool with a normal open circuit that needs voltage to close to turn on light. So no it will not complete a circuit without voltage. Where an AC test light is just a closed circuit and will complete the circuit. ( yes I know it's a light bulb in a socket but that's all an ac test light is and i don't ever use them. I always use a meter).

The photo's show the ohm's and open circuit on the test tool.

I believe this source is still good info and would use a meter because almost ever car now has some draw (Clock,memory on radio & drivers ect.) that could turn the light on partially. Be sure and put the red lead in amp hole and set meter to DC amps. https://www.wikihow.com/Find-a-Parasitic-Battery-Drain

Only if there is something "ON" somewhere causing current to flow. No current flowing, no light. Measuring amps will accurately tell you how much the draw is pulling. An incandescent test light will also be useful by observing how bright the bulb is.

You have to be careful with newer cars that have auto-diming interior lights, chimes, and anything else that stays on for a period of time after the ignition is shut off. "Keep alive" circuits are very small, will take weeks to run a battery down and won't turn a test light on.

Disconnect negative terminal from battery. Connect a test light, ammeter, whatever, to indicate current flowing from - post to - terminal. Amperage or lights on indicates current flowing through something. Knowing how much amperage is flowing can be a clue as to what is on. Allow it to sit for a minute to verify that the draw doesn't disappear due to some timed circuit. A small light bulb or relay stuck maybe 1/4 to 1/2 amp. Other items staying energized will pull more.

Isolate and disconnect circuits until the draw goes away. Once you isolate the culprit, hook the other stuff back up to verify nothing else is going on.

A DC test light is a light bulb. Nothing more, nothing less. Only difference between it and the AC test light is the voltage rating of the bulb.