Unlucky, parasitic draw, or something else?

[skaughtz]

Quick rundown of electric issues with my 2007 Camry LE 2.4L:

1. 2 years ago I replaced the alternator.
2. 1.25-1.5 years ago the car began having long, rough, sluggish starts when first fired up for the day with a 6.5-year old battery that had a 5 year warranty.
3. 1 year ago I replaced that battery with a cheap 1-year warranty Valuwhatever from Autozone that solved the problem.
4. For the past 2 months the car has been having long, rough, sluggish starts again exactly the same as before.
5. Yesterday the battery light came on the dash and has not gone away since. It is not throwing any codes to my OBDII scan tool.
6. The car only hesitates to start the first time of the day. Every subsequent start after that is completely normal until the next morning.

I just hooked up a multimeter to the battery and alternator after letting the car sit for 24 hours with a dip into the 40's in temperature last night. With the engine off, the battery dropped from 12.56V and leveled off at 12.49V after about a minute. With the engine on the battery dropped from 13.93V to 13.87V once it was at idle at around 750RPMs. The alternator leveled off at 13.93V at idle. Yesterday after driving the battery read steady at 12.6V with the engine off multiple times throughout the day.

I was actually on a BJ's run yesterday when the battery light came on, so I snagged a 30-month IBX (Interstate) battery from the club while I was in there. Before I go hooking that up, I am now curious if there is some unknown electrical issue that I should be searching out, or if it sounds more likely that the Valucrap battery I got from Autozone just decided to go down right at its year warranty mark?

Any insight is appreciated.

 

[Jimmy_Russells]

Use the mulimeter to check fuses if you want but more likely the crappy battery that was installed a year ago, is just that.

 

[eljefino]

I'd say bad luck but it wouldn't hurt to go through looking for bad grounds, bad cables, and fusebox corrosion.

Watch the voltage dip when you crank, maybe your starter is on the way out and "dragging" that is to say drawing too many amps.

My Camrys have been easy on batteries, I think they're oversized compared to what they could be.

 

[bullwinkle]

The 170K+ '07 Corolla in my sig kind of did this when I first got it from my brother-first start of the day, with a cold starter, cranked pretty slowly. Hot starter, got better but was still slower than I liked. New TYC starter fixed it.

 

[skaughtz]

Use the mulimeter to check fuses if you want but more likely the crappy battery that was installed a year ago, is just that.

I'd say bad luck but it wouldn't hurt to go through looking for bad grounds, bad cables, and fusebox corrosion.

Watch the voltage dip when you crank, maybe your starter is on the way out and "dragging" that is to say drawing too many amps.

My Camrys have been easy on batteries, I think they're oversized compared to what they could be.

The 170K+ '07 Corolla in my sig kind of did this when I first got it from my brother-first start of the day, with a cold starter, cranked pretty slowly. Hot starter, got better but was still slower than I liked. New TYC starter fixed it.

Nothing is ever simple.

I replaced the existing battery with the one I picked up yesterday. I think it was a little low on voltage despite having a "9/24" sticker on it because the car idled lower than normal after starting it the first time. I took it out for a ten minute drive quickly up and down the highway. During that time the battery light remained on, but did flash off for about one second four or five times before coming back on again. It seemed to happen when I was accelerating from a stop after taking an exit. The light remains on still.

When I got home I measured the battery and alternator again with the car idling. This time the alternator measured between 13.71V and 13.75V, while the battery was around 13.65V with the cooling fans spinning and 13.69V without. Could the difference be the bigger better battery I put in or possibly a bad voltage regulator on the alternator?

I put the old battery in my trunk and am going to test it tomorrow morning to see if it drops below 12.6V back down to the 12.49V I measured this morning.

 

[Number_35]

The battery light indicates that there's some sort of problem with the charging system - though the measured voltage when the car is running (13.9 V) is not bad.

It's a bit of a puzzle, but I wonder whether one of the diodes in the rectifier portion of the alternator has failed. If the battery was low, I would expect the charging system voltage to be > 14 V.

Just to eliminate some of the "low-hanging fruit", with the engine off I would measure the voltage between the +ve terminal and the +ve cable clamp, and the -ve terminal and its clamp. Both should be 0 V. Any voltage reading there would indicate that there's some resistance.

I would also measure the resistance between the battery's -ve terminal and the body of the alternator. It should be close to 0 Ohms.

 

[SC Maintenance]

If the battery is at 12.56Volts after 24 hours it sounds like the alternator is charging.

Have the battery tested. 1 year on a 1 year battery sounds about right for it to die. There not made like they used to be.

You can get a cheap tester for like $40 that are reasonably accurate and might help with your diagnostics.

 

[skaughtz]

The battery light indicates that there's some sort of problem with the charging system - though the measured voltage when the car is running (13.9 V) is not bad.

It's a bit of a puzzle, but I wonder whether one of the diodes in the rectifier portion of the alternator has failed. If the battery was low, I would expect the charging system voltage to be > 14 V.

Just to eliminate some of the "low-hanging fruit", with the engine off I would measure the voltage between the +ve terminal and the +ve cable clamp, and the -ve terminal and its clamp. Both should be 0 V. Any voltage reading there would indicate that there's some resistance.

I would also measure the resistance between the battery's -ve terminal and the body of the alternator. It should be close to 0 Ohms.

I measured 0V for both the positive terminal/clamp and negative terminal/clamp. With the negative probe on the batterie's negative terminal and the positive probe on the alternator body I measured 0 Ohms. I also confirmed continuity for that same negative terminal/alternator body connection.

 

[skaughtz]

I took it for another drive around town to the pharmacy and sub shop and whatnot. Started fine, idles fine, runs fine, but the battery light stays on. It does go off briefly when I accelerate from a dead stop up to 40 mph or so and get the RPM up to 3000-3500. Once I let my foot off of the gas the battery light goes off until it gets back down to idle speed (~1000 RPM) and comes back on again. I couldn't replicate it revving the engine in park in my driveway. This would make me think it is an alternator issue, but the alternator seems to be charging the battery just fine.

I am going to give her until about noon tomorrow and then test the new battery cold and hot.

 

[chemman]

Have you tested the alternator for excessive AC ripple? Set your multimeter to AC Volts (or mV if you have that setting), and while the engine is running in the 2000 - 3000 rpm range and the high beam headlamps on, place the negative test lead on the negative battery terminal and the positive test lead on the Battery terminal on the alternator.

If you have more than 50 mV of AC ripple then there could be a problem with one or more diodes in the alternator.

 

[skaughtz]

So the battery in the trunk was at a happy 12.77V this morning. It didn't even lose the surface charge. Meanwhile the new battery in the engine was at 12.56V. So my conclusion here is that something must be sucking power out of the battery overnight. I checked the fuses in the engine bay and all showed resistance, but I can't check the multi-fuses without disassembling the fuse box since they are secured in by the housing bolts. I might do that later.

I was reading about getting a baseline of parasitic draw. I disconnected the positive battery terminal and measured between it and the positive clamp. That reading was 11.79V and 2.21mA. I then disconnected the $10 LED low beams that I put in it a while ago... the kind straight from China that have a tiny little fan on them to cool them... and that same measurement went up to 11.83V and down to 2.20mA. I reinstalled the old halogen bulbs that I saved in the trunk should the cheap LEDs fail and the measurement went to 12.09V and down to 2.19mA. I am not really sure how to interpret those, so any help there would be appreciated.

As of now I think I can safely conclude:

1. The battery(ies) is not the problem.
2. The alternator is charging, but still might have issues.
3. It probably isn't a fuse issue.

Edit: I forgot to mention that disconnecting the positive terminal takes the charge on the new battery up to 12.66V. All of the cabin fuses appear to be functional as well.

Further Edit: I shined a flashlight on the multi-fuses and they at least appear fine visually.

But I decided to look deeper into the alternator, so I disconnected the negative battery terminal and left it off for a while. I eventually checked the positive pole on the alternator and the negative on the alternator body, and it read 0.280V. This seemed odd. I hooked the negative terminal on the battery back up for a minute or two and then disconnected it again. This time the alternator read 0.715V and dropped slowly from there. It appears to be continuing to drop. I am not sure exactly how to interpret this, but I would think that with the negative battery terminal disconnected, the alternator should not be giving me any readings. It didn't produce any amperage draw either time.

 

[skaughtz]

And starting her up the alternator initially read 13.91V and the battery 13.85V. It didn't wildly fluctuate as she came up to temperature.

I am running out of ideas, haha.

 

[skaughtz]

Have you tested the alternator for excessive AC ripple? Set your multimeter to AC Volts (or mV if you have that setting), and while the engine is running in the 2000 - 3000 rpm range and the high beam headlamps on, place the negative test lead on the negative battery terminal and the positive test lead on the Battery terminal on the alternator.

If you have more than 50 mV of AC ripple then there could be a problem with one or more diodes in the alternator.

It is possible that I screwed up the process, but with the engine running and the high beams on, putting the negative lead on the negative battery terminal and the positive lead on the alternator battery terminal measured 0.000V of AC and it didn't move. I couldn't rev the engine and keep the positive lead on the alternator at the same time, so this was around 900RPM or so.

 

[AdmiralYoda]

The charging light indicates a problem with the charging circuit, not the battery.

My old Toyota 4Runner just went though this. If I let it sit for about a week or two it would barely start. I bought a new cheap-o battery and it helped a little but after a few months was back to being dead after sitting for a couple weeks. I was convinced something was drawing current with the vehicle off.

After washing the engine bay (carefully) I got the alternator wet and the charging light came on and stayed on.

I put a replacement alternator in it and it has been working perfectly ever since! I can let the truck sit for months and it fires right up. No more issues. My alternator may have been weak or barely charging the vehicle while it was running. That's my theory.

 

[skaughtz]

The charging light indicates a problem with the charging circuit, not the battery.

My old Toyota 4Runner just went though this. If I let it sit for about a week or two it would barely start. I bought a new cheap-o battery and it helped a little but after a few months was back to being dead after sitting for a couple weeks. I was convinced something was drawing current with the vehicle off.

After washing the engine bay (carefully) I got the alternator wet and the charging light came on and stayed on.

I put a replacement alternator in it and it has been working perfectly ever since! I can let the truck sit for months and it fires right up. No more issues. My alternator may have been weak or barely charging the vehicle while it was running. That's my theory.

At this point that is where I am leaning. I just now had to run out so I stopped by Autozone to have them test the alternator with whatever gizmo they use when it is in the car just because why not? It passed with flying colors. The fact that the light will go off for a half second when the engine revs up to 3000+ RPM makes me lean toward it being a problem with something in the alternator, but at this point it would probably just be easier to drop the $250+ on a rebuilt Denso and call it a day. I will probably be driving around with that light on for a while though since I am now irritated about being out $120 on a battery that I didn't need. The Duralast alternator that is in there went in October 26, 2022, so it didn't even make it two years before it started having problems, assuming it is the ultimate problem.

 

[chemman]

It is possible that I screwed up the process, but with the engine running and the high beams on, putting the negative lead on the negative battery terminal and the positive lead on the alternator battery terminal measured 0.000V of AC and it didn't move. I couldn't rev the engine and keep the positive lead on the alternator at the same time, so this was around 900RPM or so.

Did you at least used the lowest AC voltage range when you measured the AC ripple? I would repeat the AC ripple test this time going across the battery terminals.

You might want to remove the alternator and have AutoZone test it with their off car test instrument.

 

[skaughtz]

I bit the bullet and swapped out the alternator. The new one is reading 14.33V on the alternator and 14.28V at the battery at idle, as opposed to the 13.75V/13.70V the previous was reading, so there is a definite improvement in charging output. After letting it sit all night the battery read 12.65V this morning, which definitely seems like the power drain on it has stopped. So the guess that a diode in the old alternator was allowing current to flow backwards somewhere seems likely.

The ongoing problem now, however, is that the battery light is still on. It stays off for about 5-10 seconds after starting the engine and then comes back on and stays on. There are still no codes being thrown, so I am at a loss for where to look next to find the cause of the battery light. I even grounded the battery to the frame to rule out a bad ground somewhere in the system and that didn't change things.

The last place that I can think to check before looking through all of the wiring is the starter, but she starts up just fine throughout the day. If anyone has any other guesses or advice it would be appreciated.

 

[skaughtz]

If you need a laugh, the same car developed a new problem, but I'm pretty sure I can track this one down.

 

[Bladecutter]

You should replace the main positive battery cable.
Sounds like there's too much resistance, and it's causing you starting issues, which you keep blaming on the battery and the alternator.

 

[chemman]

You should replace the main positive battery cable.
Sounds like there's too much resistance, and it's causing you starting issues, which you keep blaming on the battery and the alternator.

While you are at it examine the negative battery cable as well. There could be green grunge underneath the insulation near the connectors.

Good Luck with the windshield!