Battery keeps dying

suki243 · Feb 22, 2008

Hey all... My battery keeps dying... The battery that came with the car died a week or two after i got it; i had a smaller battery; i used that for a while till i got the original charged. I concluded that the alarm system sitting for a few weeks caused the first battery to die. Well, I replaced the wiring on the car, and took out the alarm system, and the battery seems to still die. It's been twice now. I even replaced the alternator cause i upgraded the sound system. The first time i ran the stereo without the new alternator. It is a 600 watt amp with a sub, it is a 120 or 130 amp 3g alternator i forget which.
I also replaced the cables that connected the engine ground, the starter relay and the alternator. What i did notice is that the + post on the battery has become black and has also made the the cable head black as well.

I drive the car weekly, usually on thursday night, friday, and the weekend then it sits in the garage till the Thursday after. This week I came on wed. I started the car , backed it out of the garage; left the door open for like a minute or two to put my stuff in. When I tried to start it the battery was dead, I was able to jump it. Drove it around and it was fine. Then today it was fine it started up right away, until i came home, i turned off the car in order to move a car blocking my driveway, I went to start the stang again... the battery was dead.... I tried to jump it, no luck... What could be wrong?
It clicks once or turns over ever so slightly

mustangmike6996 · Feb 22, 2008

load test the battery to be certain it passes the test. then check to see that the alternator is putting out 13.5-14.5 volts at 2000 rpm. then with a digital multimeter connect the meter leads in series between the positive battery cable and positive battery terminal. wait 5 minutes. look to see that you are drawing less than 0.02 amps with all doors closed and everything off in the vehicle.

****IF****** you have a parasitic draw over that many amps... pull one fuse at a time to see what circuit the power draw is in (when you pull the fuse one at a time it will bring the meter reading closer to zero) as soon as you find the one that takes you that close to zero you then know what circuit to trouble shoot.

suki243 · Feb 22, 2008

The alternator puts out 14.3 volts (according to a kraigen test, i did right when i bought it)

My grandpa came over and was looking out at the car and we wanted to bring it in the garage so we were going to jump start it. I was like hmm lets try just starting it again, and it worked, found out that some acid had built up and the cable was loose so it wasn't making the right contacts. Moved the cable around, scraped off some acid and it was fine.

Thanks mustangmike I'll definitely do that, i want to prove that i did wire it right and make sure that it isn't a short somewhere.
So I hook up my sunpro tach, start her up, disconnect the + cable from the + post of the battery, Rev to 2k rpm, put the multimeter in a series with the + cable and the + post, and wait 5 minutes to see a difference of 0.02A with the doors closed and the stereo off and the lights off.

And if there is a drawing do i pull the fuses one by one off the fuse box under the dash with the car on or off?

BarnStang · Feb 23, 2008

It sounds like you took the current test with the car running? THis is a static test with the car off. All you are looking for is to see if "something" is drawing current from the battery when it shouldn't be. I wouldn't think you hurt your meter, but I wouldn't try it again. I guess if your range was set high enough it would show current flow in the other direction-alt to batt. With the car OFF, doors closed all accessories off, put you meter on amps (current) and put in series between the + batt cable and the +batt terminal. CHeck your meter, you may need to put one of the leads in a different location to measure current. Pick a high scale and work your way down untill you can see if there is any current flowing with everything off. Like mustangmike said, should be under .02 amps, (20 milliamps) or less. If it's not less than that, you are simply isolating whatever is drawing the current by pulling out one fuse at a time until the meter indicates less than 20 milliamps. If you have any devices attached directly to the battery terminal, make sure they stay attached for the test and disconnect them one at a time too. ANy device that draws current could be the culprit.

suki243 · Feb 23, 2008

I haven't tried it yet I was just trying to clarify how to perform the test. Thanks all I'll try it later this weekend.

pabear89 · Feb 23, 2008

Simple batt drain test.
Disconnect neg term on batt.
Connect 12v test light on neg batt term and other end on cable.
If the light glows, you have a drain on the batt.

Make sure all lghts are off, dome, glove box, trunk, under hood ect.
then start pulling fuses till light goes out.

mustangmike6996 · Feb 23, 2008

pabear89 said:
Simple batt drain test.
Disconnect neg term on batt.
Connect 12v test light on neg batt term and other end on cable.
If the light glows, you have a drain on the batt.

Make sure all lghts are off, dome, glove box, trunk, under hood ect.
then start pulling fuses till light goes out.

yes this will work it is a "quick and dirty test" as some people call them.. the only thing is you cant see exactly how much current is being drawn with the light the brighter the bulb is the more current is flowing tho. either way you can do it.

if you do a parasitic draw test its with the vehicle off key off. alarm set doors locked the hood will have to be opened. (if there is a hood switch to tell if its open you need to make sure the switch is telling the alarm or car that the hood is "closed" the point of this is to mimic the car sitting with nothing operating. if there is too much draw the battery will go dead as we all know. main culprits of this are AFTERMARKET components such as radios/amps/ gauges/ lights ect... something else to look out for.

** i have also seen someone install a new starter and ground one of the small signal wires to the negative side of the starter and it cause a dead battery as well****

suki243 · Feb 23, 2008

** i have also seen someone install a new starter and ground one of the small signal wires to the negative side of the starter and it cause a dead battery as well****

Really?! I have this one wire that was connected to the firewall that is super frayed and it looks like it's going to the Starter motor. After redoing the wiring and stuff I forgot to reconnect it to the firewall, and it seemed to work fine since. However, actually 2 starts before my battery died i realized i forgot to reconnect it, and so i did.
hmm

mustangmike6996 · Feb 24, 2008

suki243 said:
Really?! I have this one wire that was connected to the firewall that is super frayed and it looks like it's going to the Starter motor. After redoing the wiring and stuff I forgot to reconnect it to the firewall, and it seemed to work fine since. However, actually 2 starts before my battery died i realized i forgot to reconnect it, and so i did.
hmm

that was most likely the ground wire... as long as it has a good connection youll be fine.

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