Battery dying

A

aztecknight

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Hi Everyone,

I'm having a problem with my 2000 lincoln ls that's been very hard to diagnose. About 5 months ago I was driving and the dash light started coming on, check traction control, check engine light, radio turned off, car started sputtering... the battery was dead... got a new battery. About 2 months ago same thing started happening, I parked the car, turned it off and tried turning it on again, completely dead. I waited a few hours and then tried starting again. It worked and it didn't fail again. So a few days ago, same thing, battery dies, I wait a couple of hours it cranks, then the battery dies again, no lights, can't even put the windows up. Take it to the shop, they jump start it, it starts to fail and dies. They go get their diagnostic equipment... waited a couple of hours, cranked her up and it started, hasn't failed in two days. Any one have any ideas? Thanks for any help you can give me.
 
Sounds to me like its your alternator. Mine did the same thing.
 
That's what the shop thinks, but how is it that after the battery appears to drain and won't crank after an episode, if I wait a few hours it will crank again? Do batteries behave this way? Thanks for the help.
 
Well if the shop has any credibility they can check and see while the car is running to see what voltage the alternator is putting out. Same for when the battery is sitting idle and the car "wont start"

The car is starting, just after the battery jumps the engine, there is no alternator juice to takeover, therefore it feels like a dead batt.

They can check by getting the car to start, and using a DMM to watch the voltage of the battery while the car is idling, if it is fluctuating all over the place and cutting out and dying, then it is 100% alternator.

I would put money on alternator by the description, but if you really wanna be sure, go ahead and do those things.
 
yeah, i guess yall are right. i just wanted to make there wasn't anything that could be missed. The shop doesn't want to do any work that isn't necessary, and since they can't get the car to fail anymore... hasn't failed since friday it starts up and runs without a problem, I'm probably just going to pick it up tomorrow and wait until it fails again so they can check it as it fails. Thanks for all the inputs.
 
why wait??? it could leave you stranded one day one day while waiting for a red light to turn green. it doesnt have to be failing to test the voltage and if it moves around then its your alternator
 
I just had this happened to me last week on the interstate at night. I replaced the alternator and everything works fine now. The instruments lights got dim slowly and then the car just started sputtering. Pulled over and cut it off and it wouldn't start. Waited about ten minutes and it started but nothing else wouldn't come on, not even the head lights. I managed to get it off the interstate where I had to call a tow truck. Next day ordered an alternator from Napa and got the battery charged so I could drive it to the shop. Everything has been working great since.
 
Well the problem is that when the car is working, like it is now, the alternator and battery read out fine. Nothing wrong, voltages are good. The problem is intermittent. It could still very well be an alternator issue, I'm starting to get concerned that its an ECU issue. I'm not sure, but don't cars nowadays have the ECU control the alternator depending on the load.... or I just might be making things up. I have the car now with nothing fixed, lets see how long it lasts before it fails again. The shop was hesitant to change the alternator because they can't verify its bad since the battery isn't dying anymore.
 
aztecknight said:
Well the problem is that when the car is working, like it is now, the alternator and battery read out fine. Nothing wrong, voltages are good. The problem is intermittent. It could still very well be an alternator issue, I'm starting to get concerned that its an ECU issue. I'm not sure, but don't cars nowadays have the ECU control the alternator depending on the load.... or I just might be making things up. I have the car now with nothing fixed, lets see how long it lasts before it fails again. The shop was hesitant to change the alternator because they can't verify its bad since the battery isn't dying anymore.
Click to expand...

The ECU (PCM, or whatever you want to call it) on the LS does control the alternator to the extent that it adjusts the voltage that it regulates to. The odds are still in favor of it being the alternator instead of the computer. It sounds like your brushes might be worn out. You might want to get one of those cheap voltage gauges that plug into the cigarette lighter and use it to monitor the voltage while you drive. You may be able to make the alternator fail on demand by making the electrical loads as big as possible. (Drive with the lights on, blower on max, ...) Failure is more likely when it is hot.
 
I'll definitely try that. I drove the car yesterday and today, and haven't had any problems. I parked the car and measured the battery, with the doors open lights on blower on high the voltage at the battery was 12.8. with the doors closed, blower off it measured 13.3. I think that's about right? no?
 
aztecknight said:
I'll definitely try that. I drove the car yesterday and today, and haven't had any problems. I parked the car and measured the battery, with the doors open lights on blower on high the voltage at the battery was 12.8. with the doors closed, blower off it measured 13.3. I think that's about right? no?
Click to expand...

If the engine was on while you took those measurements, then the alternator is clearly bad. With the engine running, you should see 13.8 to 14.2 volts.
 
Ouch, yea it is your alternator. That is about a whole volt less than what you should see
 
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