Battery keeps draining

[CrewChief]

I have a 2002 Eddie Bauer and I have been having trouble with the battery continually draining. Replaced battery and it still happens. It takes about a week to drain completely.
So far here is what I have done. Positive battery cable connected. Negative cable disconnected with volt meter between negative terminal and cable end I am reading 12.85 volts. Disconnected alternator, voltage didn't drop. Disconnected all fuses and relays, voltage didn't drop. Disconnected wire from starter solenoid to main under hood fuse box and voltage dropped to "0". Is this supposed to have voltage to it all the time and if so why is it reading through the negative cable? Also, I cannot get any type of amperage reading, just voltage. Any ideas?

 

[CrewChief]

Well, I may have just discovered part of my issue. After further reading I am supposed to be reading voltage at the negative terminal as it is completing a circuit. But I am not reading an amp draw because the fuse in my multimeter is blown. So now I will put it all back together and try again tomorrow. If anyone has any input as to what my be causing the drain please let me know. Thanks!

 

[Captain Morgan]

DON'T use your meter as an AMP meter on a lead acid battery or you'll be changing your underwear.

You'll read voltage anywhere that there is a path back to the battery, whether it's the + or - cables.

Take your alternator and have the DIODE tested as this can short and cause a constant albeit low current draw, and it's a fairly common thing.

Find out if the "voltage regulator" is an add on part so as to not buy a new alternator because some schmuck at an auto parts store wants some sales.

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[stamp11127]

Draining a battery over a weeks time is a low draw - almost parasitic. Look at the underhood and glove box lamps in addition to the alternator as possible sources.

 

[GAINMOB]

alternator will drain your battery so get the alt tested

 

[Thermo]

CrewChief, like Captain said, do not use the multimeter as an amp meter with the engine running. In a lot of cases, the alternator is outputting about 80 amps. The best multimeter is only capable of handling 10 amps. Yes, the fuse blew with a purpose.

Now, with that being said, the best advice I can give you after getting your alternator tested is to park the truck and turn it off. Remove every fuse and relay from the truck, noting which fuse goes where. Now, disconnect the negative battery cable and connect the multimeter in series with the disconnected cable and be looking for milliamps. With no fuses or relays installed, you should have 0 milliamp draw on the truck. If you have anything over about 2 milliamp draw, you have an internal failure in the wiring harness of the truck. Now, install 1 fuse. Is the multimeter still indicating under 20 milliamps? If no, remove the fuse and note this fuse location. After removing the fuse that causes the multimeter to jump over 20 milliamps or the multimeter stays under 20 milliamps, install 1 more fuse. Keep installing the fuses till there are no more to install. Then start installing the relays using the same method. Once you get all those installed, let us know what fuses/relays you could not install due to them pulling too much current. From there, we can figure out what is going on. This is the easiest method unless you have a $5000 piece of test equipment. But then, if you had that, you probably would not be asking us about this.

 

[toms89]

This is the ampere draw method I believe CrewChief is refering to and should work fine. But care must be taken not to accidently turn on any misc loads while performing the test potentially blowing the meter fuse.
How To Perform a Parasitic Draw Test - EricTheCarGuy - YouTube

I think the voltage drop method would be easier to perform.
Automotive Repair: Locating Battery Drain Using Voltage Drop - YouTube

Once you locate the circuit you can go back to the first method to test how many amps the circuit is drawing while the car is turned off if necessary.


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[Captain Morgan]

Toms89 got it, and it's not that you can't use a VM\AM but you have better not meter across two paths that lead right back to the battery.

Imagine the guy that places the - lead on to the frame and the + lead to the + battery post.

The leak test in the video would be good guidance.

Thx Toms89 for not being as lazy as the rest of us


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[Canadian Expy]

I tested mine and found a parasitic draw... Simply put the meter between the battery terminal and Cable. got my base amps and started pulling fuses till it dropped . Have you added anything new in the last year ?