55.2-59 Battery draining

[dsraven]

great advice LG.
theoretically, the mm between the battery post and the battery cable should read zero volts or amps with the key off unless there is a connection somewhere in the system to complete the circuit. a test like LG advised to do with the test light would help find the culprit with less leg work so you wouldn't have to pull a fuse and then get up to see the MM. this works as long as the "draw" has enough of a connection to light the tester bulb and you can also see the tester from the work area. I have used a buzzer for the same thing but it is annoying.
I think I asked before, but do you have a gauge package connected? is it possibly getting power with the key off?

[mr48chev]

That theory will hold true provided there is nothing in the system that draws constant power.

Things that draw legit constant power:
memory in some radios and clocks. If every time you disconnect the battery your radio loses it's channels it is drawing a few miliamps.
Alarm systems. When you turn them on they are drawing similar low amperage as the memory of the radio.

[mr48chev]

Originally Posted by Hcb3200

Well you did do like 6 things without testing between each one my guess is going to be the diode between the alternator and battery. Or a wiring that’s now hooked up correctly.
And that 12 volts you’re getting IS NOT DRAW that’s voltage. It should always say 12 unless you are actively starting with starter.
AMPs is draw and the only way to test it is put it on A and in line with the negative post and ground. It should zero if you don’t have any electronics Hooked up with switch off. ( add radios and computers and you get a super small draw ). If you want to see what your system is drawing without starting then key on meter on A 10 and put it between post and ground and you should see a small number less than 10 but greater than 1.
But most important glad it’s working. Time to move on what’s the next project on your ride.

That diode has one and one only purpose, It is a one way gate for electricity going to the exciter in the regulator.

It allows power to go to the regulator's exciter circuit when the key is on.

It blocks power from going to the ignition from the alternator when the key is off. This is so the engine will shut off because if the stator is still turning in the alternator it is still putting out power.

That is all it does and it does nothing else and has absolutely effect on the issue.

This is my biggest gripe. With this I am going to hurt some feelings and so be it but if your one of those who are guessing and throwing out wild guesses rather than actually understaning the issue QUIT THROWING OUT BS THAT HAS NOT RELATION TO THE PROBLEM That is Phungki's biggest problem every time he has a question the BS artists show up in droves with their nonsense. I have a real hard time sorting out the BS artists, with the guys who know just enough to be dangerous and the clowns who think it is funny to send him on a wild goose chase who are the same clowns who think it is funny to send the new guy to the parts house for muffler bearings.

His truck has no extra accessories that might draw power. He has clearly stated this.

That brings us to one of three things:

Battery is bad or marginal: You have to have the correct tester to test that battery and some run of the mill testers may not work on it.

Alternator is bad = blown diode. I have yet to see that he took off and took it to be properly tested.


Someone hooked something up in the truck that draws power before he bought it that he still doesn't know about. By now he should have found anything that is out of the norm. This is doubtful on this truck though.

Some accessory or item that should be on switched power is on the power all the time circuit. Going back to the alternator, with the exciter wire plug unplugged there should be no power at the end the wire when the key is off. There should only be power there when the key is on.

Now lets stop the nonsense and if you can't actully help with researched info rather than "theory" don't throw in stuff that is not relevant. What I keep seeing is somthing like a bunch of high school sophomores throwing out uninformed ideas in the first week of beginner autoshop class.

[franken]

Regarding the stop the nonsense statement there's been no shortage of fictional electrical theory spouted in this thread so why call out someone trying to make a distinction that's valid? Current and voltage aren't the same. Measuring them is also different.
Voltage is measured across a load (no interrupting the circuit), current is measured by putting an ammeter in series with the circuit (interrupting the circuit).
The OP should read a bit about Ohm's Law (it's simple) in order to understand WTF is going on and which theories are BS. In this case E is 12V there are only 2 remaining variables.
BTW, Ohm's Law was valid when each of us went to school and it is today.
Had more people understood the law and made sensible posts or none, this issue would have been resolved sooner...
Understanding a tiny bit of electrical theory goes a long way to helping people to understand when thay's on the wrong track.