2001 Cavalier Battery Drain Problem - HELP

[amberdamber7]

Hello everyone! I have been reading these threads for a long time, but this is my first post. I am at wits end!

My 2001 Cavalier has been having a battery drain problem for almost 2 years now. The battery dies overnight, especially when the weather drops below 30F. It doesn't always do this, particularly in recent weeks, when it may die within 4 hours or be just fine after 36 (regardless of the weather). We have replaced the battery twice (once was a free switch via warranty), and taken it to the dealership for testing; they told us they "could not duplicate the problem, and that battery draw tests were within spec." Autozone has tested the battery and alternator, both of which were fine. Recently, I have tried cleaning the positive and negative terminals of the battery, and also replaced the blower motor resistor (based on some posts I read here). For 2 days, the car started perfectly, and I thought I had finally solved the problem! Then, for a week, it was dead every other day or randomly while it sat in the parking lot at work. It can sit for 14 hours and be just fine, then sit for 8 hours (after a 30 mile drive) and be dead.

We found, for a long time, that pulling the fuse for the instrument cluster while the vehicle sat actually prevented the problem. Now, however, that makes no difference (as if the problem has gotten worse?). I have an aftermarket stereo that uses the windshield wiper fuse as a switched 12v power source - this was installed for 2 years before the problems began, but doesn't seem related (I tried unplugging it completely for 2 weeks without effect). Otherwise, the car is stock.

If anyone has any ideas, I would greatly appreciate it! I have done everything I can think of, and nothing has worked yet.

[96DropTopFire]

First of all, if you're worried about your battery dying while you're away from your car you can always remove the ground cable from the battery when you're done driving it. This will keep your battery from draining.

It sounds like you may have a short in your circuitry. Here's one way to test for this:

1.) Turn your car off.
2.) Pull a fuse from your fuse box.
3.) Connect a test light or voltmeter to the terminals where the fuse used to be.
There should not be any voltage across those terminals, with the exceptions of the cigarette lighter/horn, and anything else that is supposed to stay on when the car is off. If you get a voltage across the terminals, you've found a short that may be causing your battery to drain.
4.) Repeat with other fuses until short is found.

Note: You'll need to do this when your battery is not already drained.

[amberdamber7]

Here is an update after some tests I did today (thanks 96DropTopFire). I drove the car today for roughly an hour to charge the battery (after jumping it this morning). I then took my trusty multimeter and checked the amperage being drawn off the battery when the car was off. After the initial computer startup, the drain dropped to 0.08 amps (80 milliamps I think). I have read in other threads that the drain is supposed to be anywhere from 75-125 milliamps, please correct me if this is wrong!

The other thing I noted was that the drain dropped to pretty much 0 when I pulled the fuse for the instrument cluster. Also, the voltage across the battery was 12.26 (after an hour of highway driving). The instruction manual for the multimeter indicated that this represents a battery that is only 10-25% charged! I have left the battery cable off as 96DropTopFire suggested - I guess if the battery dies anyway, it really is the battery!!

Thanks everyone!

[96DropTopFire]

With the car off, the battery reconnected, and the fuse for the instrument cluster pulled, put your multimeter leads into the terminals for the instrument cluster fuse. If you read a voltage, you likely have a battery-draining short.

Also, when was the last time you had your battery tested? I know you've replaced it recently, but if you're constantly draining it to the point where you have to jump it, the strain may have taken a toll on the health of the battery.

[manicmechanix]

When you say the battery goes totally dead do you mean it won't even turn the starter or anything, and have you ever actually checked the battery voltage at the terminals when it's dead? It could be possible that your battery isn't being drained and getting dead at all. You could have a battery cable connection that is intermitently going open. When you said you drove it for awhile and battery voltage was only 12.26v (not running right?)that sounds like a battery that's not even connected to the charging system/electrical system.
Next time your battery goes dead, check the battery voltage at the battery with a voltmeter. If you have 12v at the battery but no voltage to the car, that would tell you there's a bad connection somewhere in one of the battery cables.

[amberdamber7]

I guess I didn't specify, when I say the battery is dead, usually it is just low (low enough that the car won't turn over, but the starter solenoid clicks). All the lights come on, and the radio will go, its just not enough juice to turn the engine over. Either way, I am definitely going to check the battery voltage the next time it is low! I also plan on getting the battery fully charged and doing a load test at Autozone to see if it is permanently damaged from all the jumping (I didn't realize that was a possibility until today). It hasn't been tested in about a year, but it went all summer last year without a problem!

[J-Ri]

Use a battery charger to charge the battery! The alternator is not designed to charge a dead battery. You'll burn up the alternator if you do that too much, not to mention that the battery should not be charged at the amperage that a good alternator will put out. For a battery the size of yours, I wouldn't go higher than 20A, and the lower you charge it, the longer the battery will last. Technically, .05A is the maximum parasitic draw. .25A won't kill a good battery even if left to sit for a few days. If the battery does go dead while disconnected, check for case draw. As the battery is charged, a very small amount of electrolyte evaporates. Some of it condenses over the battery and fprms a conductive layer. With your voltmeter, put one probe on a battery terminal and the other vary close to the other terminal (but only touching the plastic case). If you read anything other than the floating mV that a lot of meters show, clean the case with baking soda and water. You should also check the electrolyte level in the battery periodically, but most people either don't know that or just don't do it. I once added 20 oz of water to a battery (78 series, only slightly larger than your 75 series).

[manicmechanix]

Originally Posted by amberdamber7

I guess I didn't specify, when I say the battery is dead, usually it is just low (low enough that the car won't turn over, but the starter solenoid clicks). All the lights come on, and the radio will go, its just not enough juice to turn the engine over. Either way, I am definitely going to check the battery voltage the next time it is low! I also plan on getting the battery fully charged and doing a load test at Autozone to see if it is permanently damaged from all the jumping (I didn't realize that was a possibility until today). It hasn't been tested in about a year, but it went all summer last year without a problem!

Well yeah those details change everything. You still need to know what your battery voltage is at the battery. I take it the battery/alternator light doesn't come on right? This car has battery run down protection so it's less likely you have a parasitic drain causing this problem. It could be a lot of things, too small/defective battery or discharging to the case along the lines of what J-ri said, corrode battery terminals or bad connection, a starter that pulls too much current. Doesn't sound like this car is being properly diagnosed by whoever looked at it. Have Autozone or whoever load test the battery, starter and alternator. You live in the same city as me. I'm not looking for a repair job or anything though .

[amberdamber7]

A quick update. I tested the voltage this morning after letting the battery sit all night unplugged from the car (and in the 30's last night), and the voltage had dropped to 12.17 (down from 12.26 yesterday). I don't know if a drop of .09 volts is something to be concerned about or not! As for the battery drawing volts off the case (J-Ri, thanks), I checked that and showed .01 volts on the meter (with a solid .00 showing when the probes aren't touching anything. Again, is that enough to be concerned by? Finally, the battery is sealed, so I don't really know how I could add water even if I wanted to.

Another odd thing I noted this morning - yesterday, the draw on the battery was .08 amps, this morning it was .09. I have no idea if this is relavant or not, but thought I would mention it. I will have it charged up and tested ASAP, and post the results when its done!

[manicmechanix]

Originally Posted by amberdamber7

A quick update. I tested the voltage this morning after letting the battery sit all night unplugged from the car (and in the 30's last night), and the voltage had dropped to 12.17 (down from 12.26 yesterday). I don't know if a drop of .09 volts is something to be concerned about or not! As for the battery drawing volts off the case (J-Ri, thanks), I checked that and showed .01 volts on the meter (with a solid .00 showing when the probes aren't touching anything. Again, is that enough to be concerned by? Finally, the battery is sealed, so I don't really know how I could add water even if I wanted to.

Another odd thing I noted this morning - yesterday, the draw on the battery was .08 amps, this morning it was .09. I have no idea if this is relavant or not, but thought I would mention it. I will have it charged up and tested ASAP, and post the results when its done!

Well your battery is not showing discharge to the case or a parasitic drain, but it is way undercharged. Does your alternator/battery light stay on? You could check the batttery voltage while it's hooked up and running and see if it gets up to around 13.6 volts. You should just get the battery/alternator/starter tested. Provided your battery connections are sound it's sounding like a bad battery or maybe a starter that pulls too much current.

[J-Ri]

Did you ever check the electrolyte level? It should be to the bottom of the 3/4 way around "tubes" that lead from the top of the case. It's normal for it to drop a bit, but you should never let it get below the top of the plates. Also check the electrolyte with a battery hydrometer to make sure you don't have a weak cell. What brand of battery is this? Some of the cheap ones sold by a large nation-wide chain will never start the car past a year or so, regardless of the free replacement warranty. A lot of other cheap batteries are bad too, but those are by far the worst. Get an Interstate/Duralast/champion. They are all made by the same manufacturer, although Interstates seem to be the best of them. Possibly because that's what we sell, and our customers almost always come back to us for everything, including oil changes. With the oil change we check/fill the electrolyte, so most of the interstates I see last longer. I have a Duralast in my truck that I bought in '02. I always keep the level full, and it still passes the load test 350A for 15 seconds and it doesn't drop below 10V.

That small of a voltage drop overnight is normal, but would be less on a fully charged battery. .01A rise may just in the meter, although if a device is using "X" watts, when the voltage drops, amperage has to increase to keep the same power. last night you were using .9808W (12.26v*.08A=.9808W), and this morning you were using 1.0953W. I would attribute that to inaccuracy in the meter .1145W is very little.

[amberdamber7]

All right, an update to this problem (definitely not a solution, just more information...). I charged the battery today with a 2 amp charger for about 6 hours.. prior to the charge, the voltage was 12.28, after the charge it was 12.53 volts. I then took it straight to autozone to have it tested. The test ran for a little while, then had an error message ("Charge and retest"). I have been leaving the battery unplugged from the car every time it sits for longer than an hour, and it hasn't died since Thursday! I intend to take the battery back to autozone to have them charge it, then run the test again.

On that note, does anyone think this could be a bad diode on the alternator? Would I have seen other signs (such as a larger drain than .08 when the multimeter is set to 10A, or the car shutting down after driving for a while, or a light on my dash) beyond the discharging battery? If not, how can I test this?

[J-Ri]

You charged the battery for 12 amp-hours, I haven't seen a battery rated in amp-hours in a long time, but most in cars are in the 60 amp-hour range. Charge it longer. 12.53V is the surface charge. After charging it, remove the surface charge by turning the headlights on for 10 seconds. That will leave you with an accurate voltage, but even 12.53v is not fully charged (should be 12.6)... a surface charged battery will usually be over 13v.

If pulling the fuses didn't point to the draw, you should also disconnect any non-fused things, usually just the starter and alternator. A bad diode probably wouldn't cause any noticeable problems, several could, but wouldn't cause a draw. The voltage regulator can draw a bit if there's a partial short to ground... disconnect both alternator connectors (B+ and plastic multi-wire) and see if the draw goes away or down. I still think the problem is in the battery because .08A is barely over the limit. if you let the car sit for 100 hours (just over 4 days) the total drain on the battery would be 8 amp-hours. That would be about the equivalent of leaving the headlights on for about 30-45 minutes (which any good battery could take)

[amberdamber7]

Ok, took the battery to autozone to charge and test it. Surprise, surprise, it failed! So, bought a new battery, and will now monitor it to see if the drain is still happening or if it was just the battery.

Just for fun, I checked the AC voltage at the battery while the car was running - 32.8 volts AC on the display with the meter set to 200 VAC! Something about this doesn't seem right, and I think it points to the alternator.... any ideas? (thanks J-Ri for all your input with this problem!!)

[manicmechanix]

Originally Posted by amberdamber7

Ok, took the battery to autozone to charge and test it. Surprise, surprise, it failed! So, bought a new battery, and will now monitor it to see if the drain is still happening or if it was just the battery.

Yeah it sounds like it was the battery all along. The only question is if the alternator will keep the new one charged. It doesn't really sound like the alternator was tested.

Just for fun, I checked the AC voltage at the battery while the car was running - 32.8 volts AC on the display with the meter set to 200 VAC! Something about this doesn't seem right, and I think it points to the alternator.... any ideas? (thanks J-Ri for all your input with this problem!!)

I'm not sure but I think if you measure AC voltage between the battery terminals you'll normally get a reading like that. But if you measure AC voltage in series with say the pos battery terminal there should be very little AC voltage (the only safe way to do that with a voltmeter that I know of is to unhook the alternator positive wire and test in series there, or maybe between the positive terminal and pos cable while connected ). If you had high AC voltage from the alternator output measured in series that would indicate bad diodes in the alternator. Maybe not but that's how I understand it.