Dead bat and mystery power drain

[jcmtbfreak]

So I replaced my alternator the wed before halloween. Thursday I drive someplace, then Friday (halloween) I went to go to a party....NOTHING! Completely dead. 100%!!! I got a jump, drove around, went to the party, started up just fine afterwards, even after only being driven for 20 minutes or so. Next day, I looked at the neg battery cable, had some exposed spots, I took some electrical tape and wrapped that up so there were no bare spots. Took the newly purchased alternator back in to be tested. It passed with flying colors. I had gotten a new battery first of Oct as well. I reinstalled everything, and have been driving with NO issues till tonight. (Thats almost a month!) I go to drive to music practice for church, and NOTHING! I just drove a friend to wal mart yesterday and it worked fine! No struggle on startup or anything. Tonight I immediately started checking doors, lights, all that jazz. Everything is in place. Nothing on. Its like something just out of nowhere drains the whole battery overnight. I'm at a total loss. Any ideas? What could cause such a rapid and complete battery drain? Any fault in the alternator would be caught by a test, right? A friend had the same problem with his dodge truck, turned out to be a faulty computer. Think this could be a culprit? I know they are wired up differently. Someone else mentioned it could possibly somehow be a fuse problem? That one didn't make much sense to me...but hey, whatev. Another thing. When I installed the new alternator the first time, when I went to hook up the neg cable, electricity arched from the battery post to the connected. I've been told thats due to metal on metal issues with the cable. I took care of that one. And that hasn't happened before that, or since. With all that being said....anyone know where I should check?

 

[RobbieD]

I went to go to a party....NOTHING! Completely dead. 100%!!! I got a jump, drove around, went to the party, started up just fine afterwards, even after only being driven for 20 minutes or so. Next day, I looked at the neg battery cable, had some exposed spots, I took some electrical tape and wrapped that up so there were no bare spots.

It sounds to me like your battery cable is screwed. If the battery seemed completely dead, yet was perfectly fine after only 20 minutes of driving (i.e.- charging), that's a strong indication you've got a shaky connection in one of the main battery cables. Those things can corrode internally, and at times completely fail to pass any current. And, yours has had some open spots in the insulation, which can cause internal corrosion. Next time the battery "dies", throw a voltmeter across the battery terminals; if it shows ~12V, then take real close look at your cables. Good luck.

 

[Timo99]

It sounds to me like your battery cable is screwed. If the battery seemed completely dead, yet was perfectly fine after only 20 minutes of driving (i.e.- charging), that's a strong indication you've got a shaky connection in one of the main battery cables. Those things can corrode internally, and at times completely fail to pass any current. And, yours has had some open spots in the insulation, which can cause internal corrosion. Next time the battery "dies", throw a voltmeter across the battery terminals; if it shows ~12V, then take real close look at your cables. Good luck.

 

[CapK2]

Everyone seems to agree on this, check the connections of both power and ground cables at the battery, and check the connections at the starter and the ground point at the end of the negative (ground) cable, usually at the engine block. If these are loose or corroded this exact problem will occur.

HTH
John

 

[jcmtbfreak]

Hmmmm....yeah, my positive cable also has a gap in the insulation. It's a newer one...ooohhh say 3 years old. I'll start with a new negative connector. Speaking of which, How do I bipass the little disconnect thing that comes off the terminal? There is the ground wire that mounts to the body, then the other one. How do you bipass that so I can use a universal cable?

 

[RobbieD]

Don't bypass it; you'll need to include all of the smaller take-off leads.

To properly replace the battery cable you'll have to either find a universal replacement that includes take-off leads, or do a little electrical fabrication.

To fab a replacement cable it would be best to use new wire and terminals, for the smaller take-off leads, along with a main cable and thus duplicate what the factory put there. One way to do that would be to use a battery-end clamp that you slide the wire into and then tighten with 2 bolts.

 

[shadetree]

Don't bypass it; you'll need to include all of the smaller take-off leads.

Correct. Do not eliminate any grounds.

One way to do that would be to use a battery-end clamp that you slide the wire into and then tighten with 2 bolts.

Incorrect. Do not use this type cable ends unless you do not intend to keep the vehicle. These connectors are for temporary use only, and will give further trouble down the road. Use cables with permanently attached connectors.

After you get the cables clean and secure you still have a problem, get an ordinary test light. Disconnect the negative battery cable and place one end of the test light on the cable, and the other end on the negative battery post. If it lights up with all doors closed including glove compartment, lights and ignition off, then you have a drain somewhere. The light should not light.

Start checking circuits until you find the one that turns off the light, then diagnose that circuit. I start with the alternator. Even tho it tests ok, it can still have a leaking diode and drain the battery.

The battery can also have a short between plates, or dead cell causing it to quickly go dead. If this is the case, it will not light the test light.shady