Dead battery with no warning
 

This just happened and I won't have time to look into it for 2 days, but am dying to figure out what's going on. Went to meet people for dinner in the city, half an hour away in 85º temperatures, car drove great as always. Got back to town, stopped at a friend's for a minute, and when I went back out to the car, it wouldn't turn over. Click, click, click. Tried 3 times until it wouldn't even click. It's a '99 Boxster base with 57K.

I was able to bump start it and it seemed fine. Killed the engine a few times while rolling, and it would click, unless I did it a few times, then it would be silent, but I was able to start it each time. I parked the car for the day and then bumped into a neighbor who is a car guy, works at a shop, used to work for Interstate Batteries, delivering and installing batteries. He said batteries sometimes die in the heat, same as in the cold. I've never had a car battery die in the middle of a day of driving around- only after leaving a dome light on or in extreme cold. That would be fine, an easy fix, but I assumed if the car died while I'm in the middle of errands that the alternator or something in the charging system isn't working.

Any ideas? TIA!

I've had a battery (less than 2 years old) die without warning. It does happen.

Don't over think this! Jump start your car, drive to your local auto store or shop and have them test the battery and charging system. Get back on the road!

+1 and 8 more characters to make the computer happy.

My car did same hing last year, pushed started it and was able to drive it home.

Modern day batteries will do that, as it happened on my other car as well. Depending on battery brand installed 2 to 4 years is fairly normal life of a car battery.

Same thing driving around, stop at store and the Clicks. They just work and then they just don't.
Check voltage, non-running 12.5 ish, running 15 +/-.

Had same thing happen to me (not with my Boxster, another car) a few years ago... ran to bank and when I came out, Click, Click, Click. Luckily, the bank manager came out as this was happening and ran me over to Walmart to get a battery. (Shout-out to Suntrust Bank! That's what I call customer service!) It was a hot day too. I was concerned that it might be the alternator, but when checked, everything was fine.

As someone said, batteries can die suddenly on hot days as well...

My Boxster is probably due for a new battery - current one is coming up on 5 years old (in October).

Be thankful that you just got in your car and it was dead. I learned the hard way that on today's modern cars, the battery can go dead WHILE DRIVING and completely instantaneously shut down the car.

My daughter was driving our 2012 Jaguar XF when it happened (yes, joke about British cars, but I've learned now that it is widespread). Apparently today's auto electrics are so hypersensitive to consistent power, that the change from the battery dying can trigger things to go haywire.

I know. Don't believe me. I argued with the Jaguar dealer when they told me it was a dead battery. What kind of fool did they take me for?! I know full well that when a car is driving, it is on the alternator and the battery is just along for the ride, getting charged. Well, I was ultimately proved wrong and convinced.

The worst thing is that it happened to my daughter in So Cal on the 101 freeway, as the sun was going down. She was going at 65 mph (yeah, now I know you don't believe me - 65 on the 101, yeah sure). Then the dash lights flashed like crazy and the car just shut down. No way to get off the freeway. Emergency flashers wouldn't even work. When the tow truck arrived, they couldn't even get it out of Drive.

FWIW, my Porsche mechanic told me that Porsches have the same problem. He said that Porsche designed the system to try to shut down non-essential systems when it happens so that there is not total shut down. But he said it doesn't always work.

Yikes!

I've owned my '03S since new and it's only had 2 batteries - the original for the first 6 years or so and an Interstate battery since then. My car usually lives on a CTEK battery maintainer when it's not in use, but since moving in April I haven't organized the new garage yet to park inside. And now that it's in the shop with the engine disassembled, I am expecting it may also be time for a new battery when I get my car back. But I'm not complaining, I've had great luck with the Interstate and will probably buy another one when it's time.

When mine went, I could only start by jumping. I was 65 miles from home and it was dark. I jumped it, drove it home with my lights, no issues. So in my case, battery was kaput, but the alternator did the heavy lifting to keep me going for an hour and a half.

Yep, pretty much every battery I've owned has died a full death right away. My Jeep's battery died not too long ago. Fine one minute, completely shot the next. When the batt died in my Box, it wasn't quite so sudden, but close. Then the new battery I put in lasted about a day. Dead. Wound up I had a bad voltage regulator on my alt, but the second battery was DOA... swapped the VR, new batt... good to go.

--Don't over think this! Jump start your car, drive to your local auto store or shop and have them test the battery and charging system. Get back on the road!

Yes, dghii, hope to that tomorrow. BUT- won't the battery read as dead no matter what, since it won't do more than click, and sometimes does less? Thanks for responding. I will follow up with whatever happens...

Right, so if I go get a battery, it may be a day or so before I confirm that the alternator and VR are still good, right? I have read some here and on RennTech where the alternator and battery tests can be erroneous even when tested under load. I like life's little mysteries.. but only to a point.

I sold my 986 years ago. I changed the ignition switch multiple times.

When they fail, they do very strange electrical things (like leaving lights on even after you lock the car) which could drain your battery randomly...

Also check to see a light isn't on after you lock the car. Look at the car in the dark.
Sometimes the little sensor sticks and the light stays on. Check that the frunk light is out. I used to put my 5 year old in it...LOL (just kidding)...

Good luck.

/

Any decent auto parts store can come out and check your alternator while your car is running. Once that is checked, they can pull your battery and load test it. You will then have the cuprite (alternator or battery) isolated.

There is always a chance you simply have a bad connection at your battery....the shop will find that as well.

Ha, no. Mine was a weird series of events. My batt light came on at the track one afternoon, obviously suggesting a charging issue. No obvious issue, light then went off, drove the car home, dead the next day. Bought a new battery put it in, started, showed good voltage no worries. Dead battery next day. The battery failed for some reason, it just died. So, yet another battery, car started, voltage very low... so alt test time. Discovered it was the voltage regulator and swapped it with a Bosch unit. Good to go.

Typical charging issues, which this sounds like, are very easy to diagnose. With your car running, take a volt meter and check your voltage at the battery. You should be reading 13 1/2 to 14 1/2 volts at idle if your alternator/voltage regulator are working correctly. Don’t sweat the exact actual voltage.

After all that, it turns out to be a dead battery. As far as we know. For now.

So, the mystery history is that on Thursday I went out to sort out the problem- Tried to start the car and got half a crank, and had to bump start it. Went to AutoZone. Then for the helluvit, I tried to start it and it fired right up, like the good old days (Monday, Tuesday) and I did it a few more times. But I had a guy come out with the tester, and it tested low, but the guy thought it was probably the alternator. Hmmm. Then on the way home I passed an O'Reilly parts place and thought what the hell. The guy behind the counter was way into the cat-and-mouse game of trying to figure it out based on the symptoms I described. He tested it and said it's definitely low, so charge it or replace it. I said, but, but, why would the battery be going low unless the alternator was dying? He said to get the battery up to speed or replaced, and then look deeper for problems- doesn't make sense to look deeper until you've ruled out the battery. Sounded good.

Took it to the new mechanic I decided to try, and he put it on the charger overnight and said it only got to 0-20% of its charge. What? At O'Reilly and AutoZone they had it reading 11 volts, which is low, but how is that 20% of 12-15 volts? Said it got to 5% of cranking amps. What? I guess there are gray areas. Why was it sometimes starting and sometimes not, all of which didn't seem to be reflective of recent high-RPM driving? I guess an alternator can't charge a dead battery, but if the problem wasn't the starter, why was it dead one minute, alive the next? When I asked these questions of the 3 different guys involved at the 3 places, I got shoulder shrugs. Could it be the starter AND a dying battery? I regret that when it was dead, I didn't try to push the car when it is is gear to try to rotate the starter and/or motor to get them in a better mood where it wants to start.

The mechanic put it on a charger overnight and then called me to to tell me he had replaced the battery and to come pick it up. (I thought the universal protocol was to identify the problem, make a cost determination, and call the client to get their approval to go ahead. Never had a shop do the work and then call you.) They were pretty confident that once the good battery was in that their testing was accurate, but who knows. I asked if he could determine how old the battery was- I thought there was a letter/number code on the side or somewhere, but he said there wasn't.

Funny thing is, without him asking me, I ended up with an Interstate battery which is what I was planning to get anyway. I'd know in the next week if the new battery might be covering for the moment for underlying problems, but I'm going away next week. I will follow up if more surfaces after that, but otherwise, no news is good news. Thanks for the help, all!

Wow, that seems to be a whole lot of effort... you could have had it load tested, or they could have told you if it had a bad cell, and that would have told you it was dead. Did you test the alt with the car running? If so, what did it say? Seems like a lot of brain damage to get a new battery. Anyway, hope all is well!

Also, a battery showing 11 volts or less is, for all useful purposes, completely dead...

Voltage won't necessarily tell you if the battery is dead. The "20%" charge is referring to capacity (amp hours).

Any competent shop should have tested the alternator to ensure it and the regulator were good. Hopefully the battery fixes your issue.

Another possibility is a bad connection. Possibly at the battery, alternator, starter, distribution center or distributor block in the engine bay.

It ain't over till it's over.

In the 12 days following the battery replacement, I drove it once, went away for a week, then drove it twice more, for a total of maybe 30 miles. In that last drive, I took out out to the highway at midnight for some exercise, getting up to 5,000 RPMS in 3 or 4 gears. (Wanted to make sure all 3 digits of my digital speedometer still worked.) At some point, the battery light went on.

I took it to the shop this morning, and they looked it all over, and ran another load test. They determined that the alternator is working, but not at full bore- UNTIL you rev it past 3,000 at which point it charges well. (So I'm thinking the battery light measures roughly what's going on in the overall system, more than measuring the battery as a standalone.) They told me the alternator is on the way out and will need to be replaced eventually. Perhaps it was damaged in the struggle to keep my dying battery alive longer. It's been decades since I nursed along a weak battery, but I remember that going on for months and months, making sure to park where I could bump start it. This one stopped starting the car in the middle of a day of driving, and 5 months prior it made it through weeks of sleeping at zero degree temperatures without showing any weakness. When they replaced the battery, they told me they tested the alternator, regulator, and starter, and it was all good.

Okay, fine. But, if that's what happened, two mysteries remain. If it charges better when you get past 3,000RPMs, why did the light first go on when pushing it to 5,000? And if the light means anything, why did it not go on when the previous battery was dying and behaving erratically? I don't necessarily expect answers- it all seems more like an expression of the gray areas involved in an electrical system tied to an ECU, and maybe it should all be read as a metaphor for existential quandaries in general.