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leftywamumonkey

macrumors 6502a
Original poster
Jun 23, 2010
909
3
California
A little less than a week ago, it seemed like my battery completely died. I couldn't start the car, use the keyless entry, the electronics wouldn't turn on and I couldn't put the car in neutral. After getting the car "jumped" it seemed to run fine again, until today. Today I noticed my radio kept turning on and off and I stopped at a bank, but when I tried to unlock the doors on the car, it wouldn't work and sure enough the car wouldn't start. After waiting two minutes I heard a noise from the CD player so I decided to try starting it again and it worked. I drove it a few times and then the same problem occurred again.

My battery is consistently at 13V as well.

Could this be an alternator problem or a bad battery or something different?
I'm going to have to bring in the car tomorrow, but until then I wanted to see if anyone had a clue what it might be a result of.
 
A little less than a week ago, it seemed like my battery completely died. I couldn't start the car, use the keyless entry, the electronics wouldn't turn on and I couldn't put the car in neutral. After getting the car "jumped" it seemed to run fine again, until today. Today I noticed my radio kept turning on and off and I stopped at a bank, but when I tried to unlock the doors on the car, it wouldn't work and sure enough the car wouldn't start. After waiting two minutes I heard a noise from the CD player so I decided to try starting it again and it worked. I drove it a few times and then the same problem occurred again.

My battery is consistently at 13V as well.

Could this be an alternator problem or a bad battery or something different?
I'm going to have to bring in the car tomorrow, but until then I wanted to see if anyone had a clue what it might be a result of.

It's probably the alternator. It sounds like its not totally dead, but just barely providing any voltage to the battery. Which in turn is causing the battery to die or not last long.
 
A little less than a week ago, it seemed like my battery completely died. I couldn't start the car, use the keyless entry, the electronics wouldn't turn on and I couldn't put the car in neutral. After getting the car "jumped" it seemed to run fine again, until today. Today I noticed my radio kept turning on and off and I stopped at a bank, but when I tried to unlock the doors on the car, it wouldn't work and sure enough the car wouldn't start. After waiting two minutes I heard a noise from the CD player so I decided to try starting it again and it worked. I drove it a few times and then the same problem occurred again.

My battery is consistently at 13V as well.

Could this be an alternator problem or a bad battery or something different?
I'm going to have to bring in the car tomorrow, but until then I wanted to see if anyone had a clue what it might be a result of.

Is the ride(meaning when you gas it) sluggish at times, as if it barely had any juice?
 
Is the ride(meaning when you gas it) sluggish at times, as if it barely had any juice?

I haven't noticed that, it still has a good amount of torque too.
I just get really paranoid if the radio starts going on and off since that means once I turn the car off, it won't start for a while.


I just tried using the unlock button on my key and it worked. The car started as well.

I really don't get it. It will just start again in a few minutes. It's happened twice today.
 
I haven't noticed that, it still has a good amount of torque too.
I just get really paranoid if the radio starts going on and off since that means once I turn the car off, it won't start for a while.


I just tried using the unlock button on my key and it worked. The car started as well.

I really don't get it. It will just start again in a few minutes. It's happened twice today.

Then I highly doubt it's the alternator.

Check fuses, pull them out one by one and make sure they are pushed in good. Have the battery checked out or replaced. Also the radio could be on a constant 12v instead of the ignition, could be bad wiring if not stock.
 
Then I highly doubt it's the alternator.

Check fuses, pull them out one by one and make sure they are pushed in good. Have the battery checked out or replaced. Also the radio could be on a constant 12v instead of the ignition, could be bad wiring if not stock.

If something was wrong with the fuses, it could cause the problem I've been experiencing? The radio is stock so I presume it's wired correctly. I'll ask the mechanic to check the fuses then. I mean the battery is only a year-and-a-half old. Thanks.
 
Yeah most autoparts stores will check the whole starting/charging system for free. They have a machine to check battery, alternator, and starter.

That is going to be the best way to see whats going on.

Source: amateur mechanic forever. parts guy for a couple years.
 
what is the voltage at idle when the car is running? most alternators have voltage regulators which tell the alternator how much power to output. These can wear down over time and cause the alternator not to charge the battery. Some cars its part of the alternator and others its a replaceable part.

You can also unhook the negative lead on the battery while the car is running. If the car dies you have alternator issues
 
Yeah most autoparts stores will check the whole starting/charging system for free. They have a machine to check battery, alternator, and starter.

That is going to be the best way to see whats going on.

Source: amateur mechanic forever. parts guy for a couple years.

I wasn't aware of that, but I'm going to have my timing belt checked while I'm there. :)

what is the voltage at idle when the car is running? most alternators have voltage regulators which tell the alternator how much power to output. These can wear down over time and cause the alternator not to charge the battery. Some cars its part of the alternator and others its a replaceable part.

You can also unhook the negative lead on the battery while the car is running. If the car dies you have alternator issues

Running idle, it's still around 12.5-13V consistently.
 
When the alternator [almost] went out on my truck a couple of years ago, it was barely hovering around 14 volts, just enough to keep the engine running, but the electronics were acting weird in the interior. My mechanic had to order the new one which was going to be in the next day. (I always have him order genuine Ford parts). He was expecting to get a call from me beforehand saying I was stranded on the way to his place before repair. But it held out and I made it just fine. That was the original alternator which lasted for about 160,000 miles.

You could be experiencing the same thing; alternator providing just enough voltage to keep the battery charged enough to run the vehicle at times. Then other times, the battery can't keep up and it won't start. Have your mechanic check the output of the alternator before he changes it - if that is what is the problem.
 
When the alternator [almost] went out on my truck a couple of years ago, it was barely hovering around 14 volts, just enough to keep the engine running, but the electronics were acting weird in the interior. My mechanic had to order the new one which was going to be in the next day. (I always have him order genuine Ford parts). He was expecting to get a call from me beforehand saying I was stranded on the way to his place before repair. But it held out and I made it just fine. That was the original alternator which lasted for about 160,000 miles.

You could be experiencing the same thing; alternator providing just enough voltage to keep the battery charged enough to run the vehicle at times. Then other times, the battery can't keep up and it won't start. Have your mechanic check the output of the alternator before he changes it - if that is what is the problem.

That's interesting. Sounds similar to what's been happening to me. I'll be sure to ask the mechanic to check the output of the alternator. My car just hit 152k the other day. Thanks for the advice!


Starter solenoid maybe ? Is the battery completely dead when you get a jump ?

The starter switch.

Unfortunately I'm not sure if the battery was completely dead when I got a jump, but by the time I got back into the car after getting the car jumped, it was around 12V.
 
The times you tried to start it and it was dead was there a clicking noise like you hear when a battery is dead or did it just do nothing ?. No kind of light on the dashboard etc. ?
 
@OP: You didn't say what model car you have or how old it is. The problem could be with the battery or charging system. But newer cars are highly computerized and subject to all sorts of problems because of it. Many failures throw codes that can be read by mechanics with the proper equipment, which may indicate what went wrong.
 
The times you tried to start it and it was dead was there a clicking noise like you hear when a battery is dead or did it just do nothing ?. No kind of light on the dashboard etc. ?

No noise, no dashboard lights, nothing.

@OP: You didn't say what model car you have or how old it is. The problem could be with the battery or charging system. But newer cars are highly computerized and subject to all sorts of problems because of it. Many failures throw codes that can be read by mechanics with the proper equipment, which may indicate what went wrong.

It's a 2001 Lexus IS300.
 
I don't think the parts stores can check the timing. but if you have 152k like you said, then it almost definitely needs changing. particularly if its a belt, not a chain.
 
I don't think the parts stores can check the timing. but if you have 152k like you said, then it almost definitely needs changing. particularly if its a belt, not a chain.

I got it checked a few weeks ago and "the guy" said that it was still fine and that apparently it's changed in 90k intervals instead of the normal 60k so I'm going to get that double checked by a Japanese car service center.
 
Battery. Intermittent borderline sigh-and-die behavior. Happened to me several times with different cars over the years. Don't bother testing, just replace the thing, they're like $75.
 
I wasn't aware of that, but I'm going to have my timing belt checked while I'm there. :)



Running idle, it's still around 12.5-13V consistently.

12.5v is too low. 13v is borderline low imo. If you are comfortable with a ratchet i'd recommend unhooking the battery while the car is running.

Where did you purchase the battery from? Depending on where you purchased it it may still be covered under warranty.
 
12.5v is too low. 13v is borderline low imo. If you are comfortable with a ratchet i'd recommend unhooking the battery while the car is running.

Where did you purchase the battery from? Depending on where you purchased it it may still be covered under warranty.

I'm not sure. I bought the car a month ago. :(
 
I'm not sure. I bought the car a month ago. :(

ah ok

check your battery contacts

this is also a good idea.


If there is any type of buildup(fuzzy white/green looking stuff) on the battery contacts it can cause intermittent no start issues.

Cleaning is actually super easy depending on how your battery is arranged in the car. Remove the battery get some baking soda and a few cups of hot water. My wifes car for example has a box in the engine bay that houses the battery so I filled a plastic cup 3/4 with hot water and added baking soda then soaked the leads in the cup for a few minutes each. I also bring a spare cup to rinse the leads with clean water and a towel to dry. You can also use some paper towels with the baking soda water on them to clean the negative and positive terminals on the battery itself.
 
Something similar happened to my sister car about a year ago.

It turned out that her battery had a bad/dead cell in it and that would cause odd issues at seemingly random times.

She woudl be driving the car around all day, stopping at different shops and stores, and then one time she would come back out to the car, try to start it and nothing. She took the battery into autozone and they ran it through there tester machine a couple times. It passed 2 out of the 5 times they tested it.

If you are even slightly mechanically inclined you can take the alternator and battery off/out of the car and autozone will test both for free. Have them run each through a couple of times to make sure they are good.
 
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