Found my battery drain, now I need help

[alex99gst]

I have searched and I followed this guide: http://www.dsmtuners.com/forums/showthread.php?t=179481

First off, I have my battery relocated to the rear with a 150 amp circuit breaker. I also have the fuel pump rewired, the fans wired up to a 12v switch, and a wideband with the 12v source tapped into the cig lighter. That is the extent of my electrical work.

My test light goes out as soon as I unplug the 40A battery fuse. Is this the drain or would this always happen since it's the battery fuse? I have the positive cable running to a distribution block then to all the other positive connections.

The wideband is only on with the key in the on position, so I don't think that is the problem. The fan switch, on the other hand, has the 12v source wired directly into the distribution block. The switch breaks the connection though, so I didn't think that was it either.

Any help would be greatly appreciated.

 

[95CarbonEclipse]

The title says that you found your battery drain. Where was it coming from? Also, what was the most recent electrical work that you did?

 

[meeklo1569]

my windshield wiper motor drains my battery so i unplugged that hoe

 

[alex99gst]

I meant I found the problem, not the exact source. The last thing I did was add the 12v for the fan to the distribution block.

I just hooked the battery fuse back up and when I pulled the alternator fuse the light went out. That sounds more like my problem. My car was acting really weird and always needed to be jumped and would read 12 volts, dropping to 6 and then the car would die.

I read somewhere that touching a 12v source to the ground would kill the alternator fuse. I accidentally dropped a 12v wire when wiring up the switch and it touched the ground and sparked. The 80A alternator fuse is not visibly dead, but I'm about to test it.

There are two wires that connect to the alternator fuse. The first goes to the battery and the second to the alternator. With the alternator side wire removed and the battery side still connected, the light stays on. I'm slowly tracking this down, but any more help would really be appreciated. Thanks



EDIT: I just replaced the fuse with a known working one and still the same. The problem is the wire going from the alternator fuse to the battery. Does this mean that my positive wire is shorting to the ground somewhere along the way?

Alright, so I tried switching the wiring and still got the same results. As soon as I touch a 12v wire to the alternator fuse the light comes back on. I pulled all of the positive cable out from behind the panels and the light is still on. I'm stumped.

 

[jongreene]

Your touching parts of the wire with a testlight and watching for it to light up?

nvm...if youve already gone through that link, ill just be repeating it to you

 

[95CarbonEclipse]

my windshield wiper motor drains my battery so i unplugged that hoe

I noticed that yesterday, but Defiant's comment makes it even funnier!!

 

[steve]

Do you have a multimeter? Can it measure current?
It sounds like one or more of the diodes in the alternator is bad. The only thing on the alternator fuse should be the alternator B+ output stud but it's not exactly clear what you disconnecting and the alternator fuse also bridges part of the distribution buss.

 

[alex99gst]

Thanks Steve, I was hoping you could chime in. I have an analog multimeter. We measured the alternator output with the car running about a week ago and it was putting out 12 volts.

When I was trying to remove the alternator fuse there were two things bolted to it. One on either side of the fuse. I was disconnecting the set of two white wires that run straight to the battery and then the light would go off. There was another white wire that ran from the alternator output to the other end of the fuse I assume.

The way I'm seeing this is alternator 12v output > fuse > battery. Would it be to my advantage to pick up an alternator while I'm at the junkyard this weekend?

If you have anything else to add, I'm listening. I want to get this thing fixed already

 

[jongreene]

12v is low for alternator output. You want to be over 14v under 16v.

 

[alex99gst]

So I went the to the junkyard today and pulled a fresh looking refurbished alternator (good find) and some 80A fuses. The alternator was for a N/T and I didn't know they were different. Anyway, plugged it in just to see if it was anything internal and I am still getting a battery drain. I drew a picture to help explain what is happening.

The blue is the wire on the B+ output stud.
The gray lines are where the metal connects to wires/fuse.

-If everything is hooked up like normal, I get a drain.
-If I disconnect the fuse and leave the wires hooked up, I still get a drain.
-If I touch the red and blue together, the light is off.

With the fuse and blue wire disconnected:
-If I touch the red wire to where the blue connects to the fuse box the light comes on.
-If I touch the red and yellow wires together the light comes on.


It seems like the problem is somewhere in the fuse box with how all the wires are connected. I don't understand how this jumped out of nowhere though. I'm stuck.

 

[jongreene]

To find the drain you should really use a digital volt/ohm meter.
If you can get ahold of one, your going to use it as a jumper wire from the negative battery wire/cable to the negative terminal (red lead on cable, black on terminal).

-Run the car for 30 seconds or longer with accessories ON, leads not on the battery at this point.

-turn car OFF , place red lead on neg bat cable, black lead on negative bat terminal with the DVOM measuring amperage.

- TRICKY PART- your going to disconnect the neg. battery cable from the neg bat. terminal, but if your leads are hooked correctly, it will act as a jumper wire and all the current will flow through it still giving you a reading.

- What the meter is reading is your parasitic drain.....wait a few minutes for any computers to shut down, then start pulling fuses and when you find the biggest drop in numbers, that was your biggest drain.

hope that helps some

 

[alex99gst]

That sounds pretty confusing

I have only read bad things about disconnecting the cables to the battery with the car running. If the alternator were to spike, it would reak havoc on my electrical system. The battery acts as a filter and helps control the voltage.

 

[steve]

I have only read bad things about disconnecting the cables to the battery with the car running. If the alternator were to spike, it would reak havoc on my electrical system. The battery acts as a filter and helps control the voltage.

That's true but unless I misread the post, nobody suggested disconnecting the battery while the car was running just putting a meter in series after topping off the battery

Perhaps I missed it?

 

[alex99gst]

My bad Jon, I misread that. I get what you're saying now. I'll have to try this in 2 weeks when I get back from school. Hopefully I can get this worked out already.

 

[jongreene]

Yes DO NOT disconnect the battery with the car running.