Battery won't stay charged.

Help!

The battery in my car seems to keep dying out.

I took it to Sears on Sat morning to get it charged. First time I did that awhile back, it took 7 mins. This time it took it 40, but the machine still evaluated it as a good battery.

So I took it back home, and dropped it back in the car. All was well. Car started up nice and strong, and I drove it around the block a few times. Felt great.

Parked it in the driveway, and went inside to work on some stuff.

About 4 or 5 hours later I went back out to the car, and the batter was low on voltage again! Started up after a couple of determined tries, but I think it died sometime when it was sitting in my driveway because my station presets on my radio were reset, and so was the data on the drive computer.

What's going on??

Alternator sounds like it's going on the blink buddy....

Mine did the same thing, recharged, ran fine, killed itself....

Get your alternator checked out, you might just have to get it replaced.

Could still be a bad battery.....same thing happened in my Maxima. I went out one morning and the battery was completely dead. I jumped it with my S12, and it cranked fine. I drove it to work.....and cranked up fine 8 hrs later after work....drove it home....no problems. Next morning...same thing. Completely dead. Put a brand new battery in it, and have had no problems ever since.
I wouldn't believe anything Sears tells you. I've had nothing but problems with multiple Sears in different states trying to rip me off. I finally quit going to them. I also saw on Dateline or 20/20 a while back, that most of the Sears Automotive store's are pretty shady.....nationwide.
Go to Autozone, Kragen......they can check the battery, and alt. while on the car. It's also free and quick, and they are pretty honest, and the guy/gal doing the check could give a rat's ass if you purchase new parts through them or not.

DO NOT TRUST alternator tests..... i have had them come up as bad when i just had it rebuilt. if you notice the specs on most nissan alternators they only provide their rated amps at at least 3,000 rpms. the stands they use to test them at autozone, oreilly, advanced etc only spin the alternator at 300 or so rpm's. take your alternator to a rebuild shop. i had one for my 240 rewound for a higher output and rebearing'd for $75 with a 90 day warranty.

You may also just have a very large draw on the battery from something staying on when you shut the car off. You could test your voltage draw at the battery with the ignition off to see if anything is sucking the juice out.

I just had the same problem after my accident...

I haven't sourced it yet...

the battery is only a few months old, and the alternator has been there since February/March...

I just had the same problem after my accident...

I haven't sourced it yet...

the battery is only a few months old, and the alternator has been there since February/March...

So you still have the problem? Lemme know if you figure something out..

My alternator is relatively new, so I'm hoping it's not the problem.

You may also just have a very large draw on the battery from something staying on when you shut the car off. You could test your voltage draw at the battery with the ignition off to see if anything is sucking the juice out.

So connect a multimeter to the posts while the car is off? What should the voltage be, and what would indicate a very large draw?

voltage shouldn't exceed 12.5 volts(give or take 0.3 volts) with the car off.

14.4(give or take again) with the car on depending on what acc is also on.

If you have a multimeter, you can diagnose this yourself. If not, then invest $20 at RadioShack. Measure Voltage after a cold soak, (Engine Off for atleast 4hours or overnight) Like 'Indecisive' said it should be atleast 12.2V Engine Off. 14.4V Engine Running. Give or take .3V Then with Idle Up to 1100rpms, Turn EVERYTHING on, A/C, Rear Defrost, Fan at Full Speed, Reverse Lights, Brake Lights, Hazard Light, HighBeams, Wipers, Whatever. See what the Voltage is at that point. This is not an accepted test, But will tell you whether or not the Alternator can still put out enough Amps to keep the Voltage above 12V. If it can't, then your Alternator is getting weak.
The last test would be to test for a parasitic drain. Disconnect the Negative Terminal and hook up the Multimeter in Ampmeter mode between the Battery Negative Terminal and the Negative Battery Cable. See what the Amp Draw is. Anything over 1 Amp is considered unacceptable, and will drain the battery dead in 2-3 days if new, less than 6 hours if the Battery has some age on it.

so if voltage is over 12.5v (+/- .3v), then that means I have excess voltage draw, and i'll have to find whatever it is that's sucking the extra juice when the car's off?

if the voltage is less than 12.5, then it's probably a bad battery or a bad alternator?

The last test would be to test for a parasitic drain. Disconnect the Negative Terminal and hook up the Multimeter in Ampmeter mode between the Battery Negative Terminal and the Negative Battery Cable. See what the Amp Draw is. Anything over 1 Amp is considered unacceptable, and will drain the battery dead in 2-3 days if new, less than 6 hours if the Battery has some age on it.

So if this is the case, then what's the implication? Bad wiring somewhere?.. bad relay somewhere?...

so if voltage is over 12.5v (+/- .3v), then that means I have excess voltage draw, and i'll have to find whatever it is that's sucking the extra juice when the car's off?

if the voltage is less than 12.5, then it's probably a bad battery or a bad alternator?

Sorry, Should've explained this more carefully. If the Standing Battery Voltage is less than 11.5V, then the Battery is losing it's ability to hold a Charge, or The Alternator is not able put out enough Amps to keep the Battery Charged, or There's a Parasitic Draw draining it, Or a Combination of all three.

If the Standing Battery Voltage is more 12.5V, then the Alternator is over charging the Battery and the Battery may go sour on you if this condition exist for too long.

You will have to run all these tests in order to correctly Diagnose your Charging System problem.

So if this is the case, then what's the implication? Bad wiring somewhere?.. bad relay somewhere?...

It just means that something is still drawing current with the Key Out. There should only be 4 or 5 things drawing current. Memory for the ECU/Radio Presets, The Brake/Parking Lamp Circuit, The Hazard Lamp Circuit, The Interior Courtesy Lamps and possibly the Cig Lighter.

Assuming that No lights are on and nothing is plugged into the Cig Lighter, You should get a reading of no more than .3A. An Alarm generally draws less than .1A, armed or not, unless a Fail Secure Starter or Ignition Kill Relay has been wired in.

If you get more than 1A, then you definitely have an abnormal draw. If you have an abnormal draw, then start by removing all of the fuses one by one until the draw stops. Isolate which circuit the fuse powers and focus your diagnosis there. It can be poor wire insulation, with a partial short to ground, a relay stuck open, consistantly powering something that shouldn't be on, or any number of things.
Hope this points you in the right direction. Remember, Run all the tests first, then analyze your results. Standing Battery Voltage after a Cold Soak, then Battery Voltage @ Idle, Then Battery Voltage @ 1100rpms with Electrical System Loaded, and Finally the Parasitic Draw Test.

P.S. If the Values you're getting are in between the Values I've given you, then it's going to be a judgement call on your part. Alot times on Electrical Componets, you won't get Total Failures, Just Marginal Failures.