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Help - battery or alternator problem


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:( I drove out of the garage last night and the the entire dash light started dimming. The lights for my Tiptronic started flashing between the Manual and Automatic constantly. The gauges pretty much shutted down. I immediately stopped the car and backed up right back into my garage. I turn off the car and attempted to restart it and it wouldn't.... lost the clock setting when I attempted it.

I figured I'll recharge the battery which should fix the problem. I recharged it last night and everything looked fine this morning. When I turn on the ignition, the voltmeter display 12 volts. When I started the car, the voltage dropped slightly. The ABS and Battery light illuminated on the cluster. I figured if I drove the car, the alternator will charge up the battery. Well, it did not ... as I drove for a couple of minutes, the voltage dropped further and eventually when it dropped to 10 volts, I turned around and went straight home.

All this battery problem started about a week ago where I left the car in the garage for a week and the battery died on me when I tried starting it. I jumped start the vehicle and drove and everything seems fine. I later left the car idle for 3 days, which was until last night when I attempted to drive the car and faced with this problem.

Can someone advise if the problem I'm having is the battery or alternator? There is a date of Oct 05 label on the battery which I assume the battery was replaced then. I bought the car back in June 07. Any suggestion on diagnosing the problem.

Thanks

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  • Admin

1. How old is battery? If is is over 4 years then I strongly suggest that you consider replacing it.

2. Common causes for this sort of thing are the ignition switch (do a search here as this is covered in great detail) and a bad headlight switch.

Once the battery is taken out as a possible cause I would look at the ignition switch.

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I assume the battery is about 2 years old as the label on the battery shows Oct 05, which I assume it was replaced back in Oct 2005. I charged the battery this morning and this time around, when I started the car, the volatge shows slightly under 14 volts. The battery and ABS light is NOT illuminated on the cluster this time. I'm going to risk it and drive to my office which is about 1/2 hr away. I'll bring a jumper cable and jumper power pack with me just in case ...

I'll do a search and check the headlight and ignition switch.

Thanks

Edited by rlim
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I assume the battery is about 2 years old as the label on the battery shows Oct 05, which I assume it was replaced back in Oct 2005. I charged the battery this morning and this time around, when I started the car, the volatge shows slightly under 14 volts. The battery and ABS light is NOT illuminated on the cluster this time. I'm going to risk it and drive to my office which is about 1/2 hr away. I'll bring a jumper cable and jumper power pack with me just in case ...

I'll do a search and check the headlight and ignition switch.

Thanks

A new Costco battery is a relatively inexpensive trouble-shooting technique.

Or swap in one, temporarily, from a different vehicle.

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HI Rlim,

I had the same problem not longer than a week ago.I had porsche assist come out to the car they checked the battery and they indicated it was ok but due to the fact the battery had been charged twice he suggested I replace it. I did and the car has been great ever since no problems whatsoever. Better than asking somebody for a jumpstart at the petrol station. The other thing the porsche tech told me was to ensure the car was driven for more than half an hour a day which accounted for me going to and from work, or put the battery on trickle charge once or twice a month.

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So far so good ... battery held its charge so far. I went to Costo this afternoon and was unable to find batteries for Porsche. I'll check the other Costcos'. I'll have a chat with my mechanic tomorrow as my Beemer was towed to his garage this evening. My beemer overheated as the outlet on the radiator where the hose connects to broke. I was surprise to see that it was made of plastic... must have been due to age as the car is almost 10 yrs old. Hopefully he may know something about what Loren suggested ... investigating the ignition or head light switch.

Edited by rlim
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If your battery is holding, then your battery is 'good enough' (at this time). When my battery died, it looked as though it charged, but as soon as you take it off charge and have any kind of load on it, the voltage fell rapidly and the alarm started going off. So, either intermitent failure with alternator, or bad switches as Loren said. Get your battery tested, then you'll know.

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I suggest bring your car to a trusted auto parts store and have them test the battery.

Agree, I'll take the battery tomorrow to get it tested. I picked up a Duracell battery maintainer today from Target .. hoping that it will help extend the battery life in the future when my car sits idle in the garage for a lengthy period of time. The maintainer was very reasonable .. $19.99. Pending the battery test result, I am eyeing an Optima redtop 34/78 battery at Walmart which they're clearing out with $50 discount. In checking the forum, most folks that purchased Optima went with 34R. I will have to purchase longer battery cables for the 34/78 as the terminals are further away.

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  • 1 month later...

Well, after swapping the battery with Interstate battery. The problem is back... ABS and Battery light is back on and the voltage hovers below 12 volts. When I drove around last night, the voltage shot up between just below 14 volts and the ABS and Battery light went away. I drove the car this morning and everything was fine until I parked the car for a couple of hours while doing a little shopping. When I returned and started the car again, to my dismay, the ABS and Battery light is back on and the voltage hovers around below 12 volts again.

The battery was tested and confirmed in excellent condition. I am how pondering if the problem could be a problem with the alternator which I am speculating right now. I did a some research on the forum and there has been mentioned of regulator on the alternator that may fix the problem. I am unsure what the regulator does. Has anyone experience a similar problem with mine? I've read that the alternator is extremely expensive. Any way of checking the alternator without removing it? I would appreciate any and all advice and guidance. Thanks

Ron

Edited by rlim
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Well, after swapping the battery with Interstate battery. The problem is back... ABS and Battery light is back on and the voltage hovers below 12 volts. When I drove around last night, the voltage shot up between just below 14 volts and the ABS and Battery light went away. I drove the car this morning and everything was fine until I parked the car for a couple of hours while doing a little shopping. When I returned and started the car again, to my dismay, the ABS and Battery light is back on and the voltage hovers around below 12 volts again.

The battery was tested and confirmed in excellent condition. I am how pondering if the problem could be a problem with the alternator which I am speculating right now. I did a some research on the forum and there has been mentioned of regulator on the alternator that may fix the problem. I am unsure what the regulator does. Has anyone experience a similar problem with mine? I've read that the alternator is extremely expensive. Any way of checking the alternator without removing it? I would appreciate any and all advice and guidance. Thanks

Ron

Check that the battery negative ground strap is tight on the nearby body stud and that the ground stud itself is TIGHT to the body.

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I am having the exact same problem, and am hovering responses surrounding alternator replacement, since it is one of the strangely more expensive parts...must have something to do with copper prices. Hoping to hear more about options other than alternator replacement.

My problem was a little more interesting as the car didn't die (while in traffic), instead I noticed because the radio cut out, then I noticed the abs and airbag lights were on and then the a/c fan gauge was cycling in manuell. Car was still running fine, I looked at the volts and it read 10-11. INterior dash lights dimmed, and the litronics turned off one at a time. I proceeded to hastily lane changed to the right, in fear that the electric fans would no longer work and the car may overheat, but no problems. I managed to drive another mile to the next exit and stopped at a fueling station, called my wrench and he said I should probably turn it off and come get a new battery. I did so, and the car's peripherals returned to normal, everything worked (except radio, without code) but the volts still read just below 12. I continued to drive it another 7 miles home. Car never did die. Not sure what the issues are, even after searching the entire forum. I am hoping to get the alternator tested at the local parts store this week.

Edited by deanslist.us
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Sounds to me like the alternator is not providing a charge to the battery - simply put if it's 14-14.4v then it is, if it's 12v or less then it's not. The alternator consists of two main parts, the generator (the large motor looking bit driven by the belt) - this generates Alternatng Current or AC voltage and the 'regulator' which is a series of things called diodes that convert the AC voltage into Direct Current (DC) that is used to charge/power your car.

Now the interesting thing is I have heard you can just replace the regulator if that s the problem - there is no need to replace the entire unit. However, I'm not sure if this can be done it situ or whether the alternator needs to come out.

For future refrence - the regulator is designed/rated to keep charge on an already charged battery - so using it to charge a flat batttery usually will strain the diodes in the regulator - possibly even overheat and destroy them. So if you ever get a flat battery - then charge from an external source - never from a 'long drive' after a quick jump start.

As has been said - double check all the connections on the alternator / jump start points etc incl the main ground connection.

To load test the alternator - (with a fully charged battery!) - run ALL the electrical items (full beam etc) and if the voltage is still 14-14.4v, then your alternator/regulator is good.

I hope this helps ..

Edited by teeerex
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My problem was a little more interesting as the car didn't die (while in traffic), instead I noticed because the radio cut out, then I noticed the abs and airbag lights were on and then the a/c fan gauge was cycling in manuell. Car was still running fine, I looked at the volts and it read 10-11. INterior dash lights dimmed, and the litronics turned off one at a time. I proceeded to hastily lane changed to the right, in fear that the electric fans would no longer work and the car may overheat, but no problems. I managed to drive another mile to the next exit and stopped at a fueling station, called my wrench and he said I should probably turn it off and come get a new battery. I did so, and the car's peripherals returned to normal, everything worked (except radio, without code) but the volts still read just below 12. I continued to drive it another 7 miles home. Car never did die. Not sure what the issues are, even after searching the entire forum. I am hoping to get the alternator tested at the local parts store this week.

The DME ECU (along with some other components) is considered mission

critical and as such is designed to operated quite a lot supply voltage.

During cranking (with a weak battery) the voltage at the ECU can be

much lower than 10V and still be expected to operate.

This isn't the case for most of the other electronics in the car, and

thus takes an easier and cheaper design requiring closer to the

nominal voltage to function.

That's why the car didn't quit running.

Bill

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Sounds to me like the alternator is not providing a charge to the battery - simply put if it's 14-14.4v then it is, if it's 12v or less then it's not. The alternator consists of two main parts, the generator (the large motor looking bit driven by the belt) - this generates Alternatng Current or AC voltage and the 'regulator' which is a series of things called diodes that convert the AC voltage into Direct Current (DC) that is used to charge/power your car.

Now the interesting thing is I have heard you can just replace the regulator if that s the problem - there is no need to replace the entire unit. However, I'm not sure if this can be done it situ or whether the alternator needs to come out.

For future refrence - the regulator is designed/rated to keep charge on an already charged battery - so using it to charge a flat batttery usually will strain the diodes in the regulator - possibly even overheat and destroy them. So if you ever get a flat battery - then charge from an external source - never from a 'long drive' after a quick jump start.

For a 90 amp alternator the diodes will usually be conservatively rated at 200 amps. In any case were the alternator to try and charge a completely DEAD battery at the maximum rate you would quite soon have an EXPLOSIVE situation due to the ~1000 watts heating the battery.

The PWM, Pulse Width Modulated, regulator design is such that battery charge rates that would be too high simply do not happen.

Additionally most alternators have a self-limiting electro-magnetic "structure" design insofar as maximum current output in concerned.

On the other hand it can take more than 24 hours on a charger for a completely DEAD battery to recover to the point of accepting a full charge.

As has been said - double check all the connections on the alternator / jump start points etc incl the main ground connection.

Agreed, absolutely...

To load test the alternator - (with a fully charged battery!) - run ALL the electrical items (full beam etc) and if the voltage is still 14-14.4v, then your alternator/regulator is good.

I hope this helps ..

Edited by wwest
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Well, after swapping the battery with Interstate battery. The problem is back... ABS and Battery light is back on and the voltage hovers below 12 volts. When I drove around last night, the voltage shot up between just below 14 volts and the ABS and Battery light went away. I drove the car this morning and everything was fine until I parked the car for a couple of hours while doing a little shopping. When I returned and started the car again, to my dismay, the ABS and Battery light is back on and the voltage hovers around below 12 volts again.

The battery was tested and confirmed in excellent condition. I am how pondering if the problem could be a problem with the alternator which I am speculating right now. I did a some research on the forum and there has been mentioned of regulator on the alternator that may fix the problem. I am unsure what the regulator does. Has anyone experience a similar problem with mine? I've read that the alternator is extremely expensive. Any way of checking the alternator without removing it? I would appreciate any and all advice and guidance. Thanks

Ron

It sounds as if, truly, you have a load, battery drain, that is (intermittently) remaining on with the ignition completely off. Audio work maybe..??

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Sounds to me like the alternator is not providing a charge to the battery - simply put if it's 14-14.4v then it is, if it's 12v or less then it's not. The alternator consists of two main parts, the generator (the large motor looking bit driven by the belt) - this generates Alternatng Current or AC voltage and the 'regulator' which is a series of things called diodes that convert the AC voltage into Direct Current (DC) that is used to charge/power your car.

Now the interesting thing is I have heard you can just replace the regulator if that s the problem - there is no need to replace the entire unit. However, I'm not sure if this can be done it situ or whether the alternator needs to come out.

For future refrence - the regulator is designed/rated to keep charge on an already charged battery - so using it to charge a flat batttery usually will strain the diodes in the regulator - possibly even overheat and destroy them. So if you ever get a flat battery - then charge from an external source - never from a 'long drive' after a quick jump start.

For a 90 amp alternator the diodes will usually be conservatively rated at 200 amps. In any case were the alternator to try and charge a completely DEAD battery at the maximum rate you would quite soon have an EXPLOSIVE situation due to the ~1000 watts heating the battery.

The PWM, Pulse Width Modulated, regulator design is such that battery charge rates that would be too high simply do not happen.

Additionally most alternators have a self-limiting electro-magnetic "structure" design insofar as maximum current output in concerned.

On the other hand it can take more than 24 hours on a charger for a completely DEAD battery to recover to the point of accepting a full charge.

As has been said - double check all the connections on the alternator / jump start points etc incl the main ground connection.

Agreed, absolutely...

To load test the alternator - (with a fully charged battery!) - run ALL the electrical items (full beam etc) and if the voltage is still 14-14.4v, then your alternator/regulator is good.

I hope this helps ..

Thanks wwest - I was well aware that I was over simplifiying things with todays alternators / regulators (trying to keep it simple!) - the other key fact of course is they supply a constant voltage/current regardless of RPM on the alternator itself, unlike a dynamo - all part of the regulator/electronics as you have said.

All the best - Richard.

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Thanks wwest - I was well aware that I was over simplifiying things with todays alternators / regulators (trying to keep it simple!) - the other key fact of course is they supply a constant voltage/current regardless of RPM on the alternator itself, unlike a dynamo - all part of the regulator/electronics as you have said.

All the best - Richard.

That's not entirely accurate. Alternators do a much better job of

charging at lower engine RPM, simply because they are geared higher

and spin faster than generators did in the good old days.

The commutators in generators could not survive very high speeds, and

thus were geared lower so they would not over-speed at the highest engine

speed. As a result their output at low speeds/idle was poor.

Alternators do much better, but they do not generate as much power at idle

as they do at even slightly higher RPM.

Bill

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Thanks wwest - I was well aware that I was over simplifiying things with todays alternators / regulators (trying to keep it simple!) - the other key fact of course is they supply a constant voltage/current regardless of RPM on the alternator itself, unlike a dynamo - all part of the regulator/electronics as you have said.

All the best - Richard.

That's not entirely accurate. Alternators do a much better job of

charging at lower engine RPM, simply because they are geared higher

and spin faster than generators did in the good old days.

The commutators in generators could not survive very high speeds, and

thus were geared lower so they would not over-speed at the highest engine

speed. As a result their output at low speeds/idle was poor.

Alternators do much better, but they do not generate as much power at idle

as they do at even slightly higher RPM.

Bill

We seem to have gone way off topic .. but I enjoy a good old fashioned debate ;)

In your last statement - are you comparing an alternator vs a generator at higher RPM as I'm confused with what you are saying? Or you are saying that an alternator does not generate equal power at idle than at say 1500RPM ? If so, then I have to disagree.. lol..

For those still interested - this link below explains the two in a lot more detail ...

Alternator vs Generator/Dynamo

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Thanks wwest - I was well aware that I was over simplifiying things with todays alternators / regulators (trying to keep it simple!) - the other key fact of course is they supply a constant voltage/current regardless of RPM on the alternator itself, unlike a dynamo - all part of the regulator/electronics as you have said.

All the best - Richard.

That's not entirely accurate. Alternators do a much better job of

charging at lower engine RPM, simply because they are geared higher

and spin faster than generators did in the good old days.

The commutators in generators could not survive very high speeds, and

thus were geared lower so they would not over-speed at the highest engine

speed. As a result their output at low speeds/idle was poor.

Alternators do much better, but they do not generate as much power at idle

as they do at even slightly higher RPM.

Bill

We seem to have gone way off topic .. but I enjoy a good old fashioned debate ;)

In your last statement - are you comparing an alternator vs a generator at higher RPM as I'm confused with what you are saying? Or you are saying that an alternator does not generate equal power at idle than at say 1500RPM ? If so, then I have to disagree.. lol..

Yes, it does not give the same output at idle as 1500 rpm.

Disagree all you like.

Bill

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any insight on how to remove the alternator? I found some cool tips and tricks in another thread involving wd-40 and a hammer, but now I am nearing the idea of removing my intake manifold to wrench the thing out. Never found a diy...not yet anyway.

Duh, I found one, if anyone is interested another DIY listed here includes removing the alternator to get to your secondary air injection...I knew I saw it somewhere.

Edited by deanslist.us
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The reason alternators are better then generators is the low rpm output, and it has little to do with the gearing per say. It's due to the fact that gen put out DC and alternaors put out AC converted to DC by the reg. Ac is more stable easier to regulate, and output of the AC is greater then that of a DC generator at a given rpm. Generators rely on permanent magnets to generate the output, alternators rely on a voltage source for field excitation.

Anyway back to the subject at hand - A battery in good condition and fully charged should have an output of about 12.4 volts at rest.

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The reason alternators are better then generators is the low rpm output, and it has little to do with the gearing per say. It's due to the fact that gen put out DC and alternaors put out AC converted to DC by the reg. Ac is more stable easier to regulate, and output of the AC is greater then that of a DC generator at a given rpm. Generators rely on permanent magnets to generate the output, alternators rely on a voltage source for field excitation.

Anyway back to the subject at hand - A battery in good condition and fully charged should have an output of about 12.4 volts at rest.

The reasons are exactly as I posted earlier.

The alternator gives better output at lower engine speed because

the alternator can spin faster without blowing up physically, than

could a generator, due to the lack of the segmented commutator,

and thus is geared higher. This is THE primary reason for their

use. (and, today, they are loads cheaper)

They became feasible for general use when silicon rectifier diodes

got cheap enough in the early to mid '60s.

A generator may use permanent magnets to bootstrap the system

but there is a still a field winding, as that is how the regulator controls

the output. Same as in an alternator.

For the people who don't want to believe alternator output is not as

high at lower RPM, see this output graphs about halfway down this page:

http://www.delcoremy.com/Alt24SI.aspx

(note though, the graph shows alternator RPM, not engine RPM,

you'll have to correct it for the gear ratio in your particular application.

The alternators discussed on that page have a max speed of 12,000

RPM. So, if hooked, say, to a 911 with a 7000 RPM redline, it might

be geared about 0.6:1. So at 2000 RPM alternator speed on the graph

the engine would be spinning 1200.)

Bill

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The reason alternators are better then generators is the low rpm output, and it has little to do with the gearing per say. It's due to the fact that gen put out DC and alternaors put out AC converted to DC by the reg. Ac is more stable easier to regulate, and output of the AC is greater then that of a DC generator at a given rpm. Generators rely on permanent magnets to generate the output, alternators rely on a voltage source for field excitation.

Anyway back to the subject at hand - A battery in good condition and fully charged should have an output of about 12.4 volts at rest.

The reasons are exactly as I posted earlier.

The alternator gives better output at lower engine speed because

the alternator can spin faster without blowing up physically, than

could a generator, due to the lack of the segmented commutator,

and thus is geared higher. This is THE primary reason for their

use. (and, today, they are loads cheaper)

They became feasible for general use when silicon rectifier diodes

got cheap enough in the early to mid '60s.

A generator may use permanent magnets to bootstrap the system

but there is a still a field winding, as that is how the regulator controls

the output. Same as in an alternator.

For the people who don't want to believe alternator output is not as

high at lower RPM, see this output graphs about halfway down this page:

http://www.delcoremy.com/Alt24SI.aspx

(note though, the graph shows alternator RPM, not engine RPM,

you'll have to correct it for the gear ratio in your particular application.

The alternators discussed on that page have a max speed of 12,000

RPM. So, if hooked, say, to a 911 with a 7000 RPM redline, it might

be geared about 0.6:1. So at 2000 RPM alternator speed on the graph

the engine would be spinning 1200.)

Bill

wrjet - so why are you quoting me????????? if you read my input i am not disagreeing! BTW my input is fact!

Edited by KevinMac
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