Need help. Bad battery or bad connectors?

[SonicYan]

Hi all, just needed some help. Read through a lot of threads using the search and am still a bit confused as to what is the problem. I'm hoping its just a bad battery cable/connector based on symptoms my car is showing and what others have posted already. Anyway, here goes:

This problem has been going on since last week. I was driving on the freeway, and all of a sudden, the battery light came on. Hoping for the best, I just drove all the way home. Made it home safe. I guess that eliminates any alternator problems.

The next day, car wouldn't start. It wouldn't turn over, no power at all, no dome lights. I jump started the car, and brought the car to pep boys to have the battery tested, since the battery was just a week old. (brand new Optima Blue top) Everything checked out fine, alternator was charging, battery was fully charged. So now, I'm guessing I probably have a drain somewhere.

So I left the car alone overnight. The next morning, I started the car, expecting the battery to be fully dead. To my surprise, it started. So now I'm not sure if something is draining the battery. Didn't have any problems for two-three days.

Beginning this week, it started again. I was already guessing it was probably the connectors that were dirty or something, so I wiggled the negative terminal a little, and then the car started. Last night heading home from work and this morning, the car wouldn't start again. The wiggle trick didn't work this time. I tried cleaning the battery connectors with baking soda and water. Not sure if I cleaned it well, but either way, no dice, car wouldn't start. So I was about to jumpstart the car. Jumper cables were already connected to the battery, just needed to connect it to the host. I accidentally shorted the jumper cables by touching the red clip to the black clip. Lo and behold, I notice my dome and door lights came on. I started the car, and it worked. Just now, on the way to work, car won't start again. Did the short circuit trick, car started. On the way to work, battery light comes on. Made it all the way to work (half hour drive), turn off the car. As soon as I turn the car off and I try to restart, all power is again gone.

So what do you guys think? Dirty connectors? Bad battery? Bad cables? If so, do I buy the whole battery cable or just the connector at a car store? Sorry for all these questions, not really a DIY guy.

Cliffs: Battery light on during driving, car didn't die, not alternator. Next day, car wouldn't start, no power at all. Jumpstart, alternator and battery tested ok. Problem happens again, shorting jumper cables power up car. Haha, hope that made sense.

 

[Defiant]

This problem has been going on since last week. I was driving on the freeway, and all of a sudden, the battery light came on. Hoping for the best, I just drove all the way home. Made it home safe. I guess that eliminates any alternator problems.

Most likely your alternator's dead. I've driven from San Mateo to Napa, and another time from Grass Valley to Galt on battery-only.

 

[SonicYan]

Well I did bring it to Pep Boys, they said the battery was fully charged, and that the charging system/alternator was ok.

I tested myself using a multimeter. Was getting a reading above 12V. This means its charging right?

 

[luv2rallye]

With engine running you should get 13.9-14.9 volts at the battery. Auto stores only test for go/no-go dc voltage and even that is done poorly. There are over a dozen tests that only an alternator/starter repair shop will do. Take your alt there to be tested.

For a quick and simple battery test measure battery voltage with everything turned off (should be at least 12.5V). Now just turn headlights and blower on (not engine or anything else). Battery voltage should be at least 12.0V. If not battery is bad or it was never charged.

You can test for a battery drain here (use series light bulb test): http://www.dsmtuners.com/forums/showthread.php?t=179481

 

[Starscream]

Did any other light came on? If there were three lights, it means alternator malfunction. Once my alternator died and I still could drive a long way back home, and start the car the next morning.

Go check your alternator, and report back to us.

 

[siceclipse]

hey guys i dont want to start a new thread and this seems to be the right place

I changed my alt with an OEM one a month or 2 ago and just 2 days ago i noticed that my lights dim with the brakes and the radio shuts off too when comming to a stop.

I also should add that i wired my fans together and leave them on with the car off to cool the engine before working on the car. the day i worked on the car the engine wouldnt turn over...

new battery needed right??

again sorry for the hijack, any responce is apreciated.

 

[SonicYan]

Did any other light came on? If there were three lights, it means alternator malfunction. Once my alternator died and I still could drive a long way back home, and start the car the next morning.

Go check your alternator, and report back to us.

By other light, what do you mean? The only problem light coming on was the battery light.

I'll check the alternator again with a better multimeter. My multimeter's messed up. Was reading 21.5V when the car was ON. Tested the multimeter on a regular AA 1.5V and was reading 2.6...

Also, if its a bad alternator, can anyone explain to me why everytime I try to start the car right now, it won't start at all? No power, or anything, all dome lights, dashboard lights won't turn on, won't even turn over. BUT...as soon as I "jumpstart" the car by shorting the battery by touching the red and black clips on the other end of the jumper cables, all power is restored. Still related to a bad alternator?

On a different note, how long will the battery last if the car is driven on just battery power alone if the alternator were bad? I've driven the car for a week already, around 250 miles, all this time having this problem. Sound about right running on battery power alone?

 

[SonicYan]

With engine running you should get 13.9-14.9 volts at the battery. Auto stores only test for go/no-go dc voltage and even that is done poorly. There are over a dozen tests that only an alternator/starter repair shop will do. Take your alt there to be tested.

For a quick and simple battery test measure battery voltage with everything turned off (should be at least 12.5V). Now just turn headlights and blower on (not engine or anything else). Battery voltage should be at least 12.0V. If not battery is bad or it was never charged.

You can test for a battery drain here (use series light bulb test): http://www.dsmtuners.com/forums/showthread.php?t=179481

Thanks. Will test this out. I'll try searching for drains as well. I've heard of the light bulb test but didn't know the details.

 

[siceclipse]

with no alternator you're running straight off the battery constantly. so the battery will die or not provide enuff charge to start the car or illuminate your interior lights.

when you put another new one in your just draining that one next.

 

[SonicYan]

Update:

The problem seems to have vanished for no apparent reason since yesterday afternoon. No need to arc the battery just to jumpstart it. Battery light was gone too. Borrowed a multimeter from a friend. Reading 12.5 V from the battery, 13.11V from the alternator. I have an UDP which is the reason for the low alternator reading. But yeah, other than that, me and my friend can't seem to duplicate the problem anymore.