2001 996 Carrera 4

[sburkes]

I am experiencing a charging problem. When the engine starts and the instrument cluster clears the battery light goes out. The voltage meter indicates and initial charge of 13v however that eventually drops and finally starts battery drain. I have done no actual testing yet other the obvious-fuses. What major component(s) do I begin to test? This is my first post so I apologize in advance for protocol violations.

Steve

[Loren]

I would start with the battery - if it is over 1 year old then it can easily go bad.

Also, have you added anything electrical or electronic to the car (that could cause a power drain)?

[sburkes]

I would start with the battery - if it is over 1 year old then it can easily go bad.

Also, have you added anything electrical or electronic to the car (that could cause a power drain)?

Thanks for your reply. The battery is new (two weeks) and nothing has been added. All original equipment.

Steve

[Loren]

Unless you have some huge power drain it is likely time to have the alternator checked.

Where are you located?

[sburkes]

Unless you have some huge power drain it is likely time to have the alternator checked.

Where are you located?

I Agree. I am located near Philly, Pa.

[Loren]

You need to find someone with the Durametric software, or a PST2 or a PIWIS tester to check your alternator.

Or, you will need to remove it and have an alternator shop test/repair it.

[sburkes]

You need to find someone with the Durametric software, or a PST2 or a PIWIS tester to check your alternator.

Or, you will need to remove it and have an alternator shop test/repair it.

I have the latest Durametric SW and have run the test. Which component do you suggest? I have run the engine test and get 12v result? Maybe I'm not running the right test or am not understanding the result??? I have run the other tests without much success in that some load and some don't. The instrument panel passes. So I am open to suggestions on running the Durametric tests.

[Loren]

If you look at the alternator voltage with the engine running it should be 14 volts (or close to it).

[sburkes]

If you look at the alternator voltage with the engine running it should be 14 volts (or close to it).

So am I to assume that if it begins at ~12v (fully charged battery) and slowly drops that the alternator is not charging and that would be the problem?

[sburkes]

If you look at the alternator voltage with the engine running it should be 14 volts (or close to it).

So am I to assume that if it begins at ~12v (fully charged battery) and slowly drops that the alternator is not charging and that would be the problem?

Tested again with

Durametric..results are it started at 14v fell to below 12v and continued to drop....so any ideas on where to find information on the correct method to remove the alternator external testing?

[sburkes]

If you look at the alternator voltage with the engine running it should be 14 volts (or close to it).

So am I to assume that if it begins at ~12v (fully charged battery) and slowly drops that the alternator is not charging and that would be the problem?

Tested again with

Durametric..results are it started at 14v fell to below 12v and continued to drop....so any ideas on where to find information on the correct method to remove the alternator external testing?

Update: I removed the alternator and had it bench tested. It passed all tests. I have re-installed it and am having the same problem. The vehicle has been sitting (2 wks) and the battery has not dropped below ~11 volts. After re-installing the alternator, it started fine but the same problem, the voltmeter goes above 13 volts and then begins to drop as before. So any ideas as to what to test next?

[Loren]

Hmm... time to look for a power drain.

Poor grounds? etc.

[sburkes]

Hmm... time to look for a power drain.

Poor grounds? etc.

I thought of that but discounted it because the battery doesn't seem to drain at a fast pace and why does the instrument panel gauge go to ~13 volts at start and then drop to less than 10 volts? Could the drain be only on engine running? and why doesn't the headlights/heater work will the engine is running? Still struggling along.....

[OCNYPORSCHE]

Are the battery terminals clean. Sometimes it can be as simple as that. I not sure if the 996 has a voltage regulator. Sometimes that can cause issues like this too.

[sburkes]

Are the battery terminals clean. Sometimes it can be as simple as that. I not sure if the 996 has a voltage regulator. Sometimes that can cause issues like this too.

Yupe, new battery as of last month. I was told (at the alternator bench test) that the voltage regulator is integrated in the alternator. That may not be true...any thoughts?

[OCNYPORSCHE]

Do you know if the battery terminal wires (from the car) were cleaned too? Even if the battery is new, if there is corrosion on the wire connectors, it make a bad connection. Charging system are relatively simple, so if it is not the battery, the connectors, then it is mostly likely the alternator. How is the tension on the belt? Sometimes a loose belt can cause this, but I think it is an auto tensioner.

[sburkes]

Do you know if the battery terminal wires (from the car) were cleaned too? Even if the battery is new, if there is corrosion on the wire connectors, it make a bad connection. Charging system are relatively simple, so if it is not the battery, the connectors, then it is mostly likely the alternator. How is the tension on the belt? Sometimes a loose belt can cause this, but I think it is an auto tensioner.

The connectors (battery end and engine ends) look clean. The alternator was bench tested good. The serpentine belt is tight and clean. The tensioner was adjusted upon re-intallation of the alternator. The tensioner is an auto tensioner. I'm wondering if there are some voltage test points procedures I could try...

[wwest]

Do you know if the battery terminal wires (from the car) were cleaned too? Even if the battery is new, if there is corrosion on the wire connectors, it make a bad connection. Charging system are relatively simple, so if it is not the battery, the connectors, then it is mostly likely the alternator. How is the tension on the belt? Sometimes a loose belt can cause this, but I think it is an auto tensioner.

The connectors (battery end and engine ends) look clean. The alternator was bench tested good. The serpentine belt is tight and clean. The tensioner was adjusted upon re-intallation of the alternator. The tensioner is an auto tensioner. I'm wondering if there are some voltage test points procedures I could try...

Your engine compartment is overheating....

But check and be sure the negative lead from the battery is FIRMLY connected to the body, tighten the nut.

You might want to check the body connection for the negative side of the alternator also.

The voltage regulator has a temperature sensing function so that as the ambiant temperature rises the battery is charged to a lower and lower level.

That sensing element within the alternator voltage regulator might be failing and a bench test wouldn't be likely to indicate, detect, it.

Once the voltage drops open the engine lid and cool the alternator with a fan and see if the voltage rises.

Edited March 27, 2008 by wwest

[sburkes]

Do you know if the battery terminal wires (from the car) were cleaned too? Even if the battery is new, if there is corrosion on the wire connectors, it make a bad connection. Charging system are relatively simple, so if it is not the battery, the connectors, then it is mostly likely the alternator. How is the tension on the belt? Sometimes a loose belt can cause this, but I think it is an auto tensioner.

The connectors (battery end and engine ends) look clean. The alternator was bench tested good. The serpentine belt is tight and clean. The tensioner was adjusted upon re-intallation of the alternator. The tensioner is an auto tensioner. I'm wondering if there are some voltage test points procedures I could try...

Your engine compartment is overheating....

But check and be sure the negative lead from the battery is FIRMLY connected to the body, tighten the nut.

You might want to check the body connection for the negative side of the alternator also.

The voltage regulator has a temperature sensing function so that as the ambiant temperature rises the battery is charged to a lower and lower level.

That sensing element within the alternator voltage regulator might be failing and a bench test wouldn't be likely to indicate, detect, it.

Once the voltage drops open the engine lid and cool the alternator with a fan and see if the voltage rises.

Thanks for that. I wonder if it could be overheating since it drops within 1 minute. It could be the sensor as you mentioned in the voltage regulator of the alternator because I did an additional test-at the connector post from the battery to the alternator, I started the engine and measured at the connector, it measured above 13 volts but slowly began to drop to 12 volts and continued. I stopped the engine and disconnected the battery lead from the terminal and measured again, the reading was 12.6 volts. After reconnecting the battery back on the lead, I restarted the engine checked the voltage again it was above 13 volts BUT this time I pulled the battery lead off the connector and measure the voltage on the alternator post (without the battery connected) and it measured above 12 volts but began to drop to ~10 volts. I reconnected the battery and retested to 12+ volts. So the only conclusion at this point is that there is something within the alternator that is defective and it doesn't show up on the bench test. Any thoughts as to whether I continue other tests or "bite the bullet" and replace the alternator which of course is non-returnable should it not solve the problem....

Edited March 27, 2008 by sburkes

[jr_152]

Do you know if the battery terminal wires (from the car) were cleaned too? Even if the battery is new, if there is corrosion on the wire connectors, it make a bad connection. Charging system are relatively simple, so if it is not the battery, the connectors, then it is mostly likely the alternator. How is the tension on the belt? Sometimes a loose belt can cause this, but I think it is an auto tensioner.

The connectors (battery end and engine ends) look clean. The alternator was bench tested good. The serpentine belt is tight and clean. The tensioner was adjusted upon re-intallation of the alternator. The tensioner is an auto tensioner. I'm wondering if there are some voltage test points procedures I could try...

Your engine compartment is overheating....

But check and be sure the negative lead from the battery is FIRMLY connected to the body, tighten the nut.

You might want to check the body connection for the negative side of the alternator also.

The voltage regulator has a temperature sensing function so that as the ambiant temperature rises the battery is charged to a lower and lower level.

That sensing element within the alternator voltage regulator might be failing and a bench test wouldn't be likely to indicate, detect, it.

Once the voltage drops open the engine lid and cool the alternator with a fan and see if the voltage rises.

Thanks for that. I wonder if it could be overheating since it drops within 1 minute. It could be the sensor as you mentioned in the voltage regulator of the alternator because I did an additional test-at the connector post from the battery to the alternator, I started the engine and measured at the connector, it measured above 13 volts but slowly began to drop to 12 volts and continued. I stopped the engine and disconnected the battery lead from the terminal and measured again, the reading was 12.6 volts. After reconnecting the battery back on the lead, I restarted the engine checked the voltage again it was above 13 volts BUT this time I pulled the battery lead off the connector and measure the voltage on the alternator post (without the battery connected) and it measured above 12 volts but began to drop to ~10 volts. I reconnected the battery and retested to 12+ volts. So the only conclusion at this point is that there is something within the alternator that is defective and it doesn't show up on the bench test. Any thoughts as to whether I continue other tests or "bite the bullet" and replace the alternator which of course is non-returnable should it not solve the problem....

Its a bad alternator. Have it bench tested at another shop. With your engine running, if you don't get 13.8 volts at the battery, then your alternator is bad.

[wwest]

Do you know if the battery terminal wires (from the car) were cleaned too? Even if the battery is new, if there is corrosion on the wire connectors, it make a bad connection. Charging system are relatively simple, so if it is not the battery, the connectors, then it is mostly likely the alternator. How is the tension on the belt? Sometimes a loose belt can cause this, but I think it is an auto tensioner.

The connectors (battery end and engine ends) look clean. The alternator was bench tested good. The serpentine belt is tight and clean. The tensioner was adjusted upon re-intallation of the alternator. The tensioner is an auto tensioner. I'm wondering if there are some voltage test points procedures I could try...

Your engine compartment is overheating....

But check and be sure the negative lead from the battery is FIRMLY connected to the body, tighten the nut.

You might want to check the body connection for the negative side of the alternator also.

The voltage regulator has a temperature sensing function so that as the ambiant temperature rises the battery is charged to a lower and lower level.

That sensing element within the alternator voltage regulator might be failing and a bench test wouldn't be likely to indicate, detect, it.

Once the voltage drops open the engine lid and cool the alternator with a fan and see if the voltage rises.

Thanks for that. I wonder if it could be overheating since it drops within 1 minute. It could be the sensor as you mentioned in the voltage regulator of the alternator because I did an additional test-at the connector post from the battery to the alternator, I started the engine and measured at the connector, it measured above 13 volts but slowly began to drop to 12 volts and continued. I stopped the engine and disconnected the battery lead from the terminal and measured again, the reading was 12.6 volts. After reconnecting the battery back on the lead, I restarted the engine checked the voltage again it was above 13 volts BUT this time I pulled the battery lead off the connector and measure the voltage on the alternator post (without the battery connected) and it measured above 12 volts but began to drop to ~10 volts. I reconnected the battery and retested to 12+ volts. So the only conclusion at this point is that there is something within the alternator that is defective and it doesn't show up on the bench test. Any thoughts as to whether I continue other tests or "bite the bullet" and replace the alternator which of course is non-returnable should it not solve the problem....

Caution..DANGER...!!

Never, NEVER disconnect the battery from the alternator circuit with the engine running.

The battery is an integral part of the method of regulating the output voltage of the alternator, without the battery you would possibly get 100 volt spiking from the alternator and that would most certainly damage some of the electronic components.

It looks, reads as if you disconnected the alternator output lead from the battery and thus all the circuit loads...I HOPE.