Alternator, Generator, Battery

[wvicary]

Are you sure you only have one battery? There has also been some issues with the ground cable connection located near the left seat/floor pan.

[ekstroemtj]

Hi. I am pretty shure i have just one under drivers seat. In the rear i can see only black round box which is the bose system . I will have a closer look this weekend.

[jw_928]

My secomd battery was under the box in the back. I had to remove the box to see the battery.

[ekstroemtj]

Here i am again. I try some things today because the car is still at home.

First of all, i dont have a second battery in the trunk.

After replacing the new battery last weekend the car stay all week without driving.

I open the hood and tested voltage in engine bay plus / minus port.

Reading was 11.30

I try to start the car. Starter turning but engine not starting.

Using my s to make a jump start. Car is starting and running.

I left it for some minutes running, drive a few kilometers and shut down the engine.

Waited a few minutes and tested the voltage again.

Reading 12.30

I started the again

Reading 13.96

Does this test show me that the alternator is ok and working

Proper? Or is it possible that a mistaken alternator also would show

This reading?

Thank you again

[ekstroemtj]

Here is the multimeter reading

[ekstroemtj]

Sorry for my mistakes. I am writing on mobile phone.

Multileter Reading with engine shut down

12,...

Multimeter Reading with running engine

13,9......

[ALEV8]

If it's below 12.7 with the car off it is dead. Replace it.

[JFP in PA]

Sorry for my mistakes. I am writing on mobile phone.

Multileter Reading with engine shut down

12,...

Multimeter Reading with running engine

13,9......

Your voltage is too low, should be between 13.5 and 14.5V with the engine running, you are reading battery voltage so either the alternator or voltage regulator (inside the alternator) is bad.

[ekstroemtj]

JFP thank you!

You said must be between 13,5 and 14,5

But my reading 13,98 is in the range you mentioned

[Ahsai]

What's the voltage reading if you turn on the headlight, the a/c, and the rear defroster at the same time during idling? If it's below 13.5v, your alternator is likely bad. That's a crude load test before you can get the alternator tested properly at the shop.

Have you tried to test for battery drain after car is locked? One of your posts said the battery dropped to 11.3v overnight. Either the battery was bad/not fully charged or you have a parasitic drain.

[JFP in PA]

What's the voltage reading if you turn on the headlight, the a/c, and the rear defroster at the same time during idling? If it's below 13.5v, your alternator is likely bad. That's a crude load test before you can get the alternator tested properly at the shop.

Have you tried to test for battery drain after car is locked? One of your posts said the battery dropped to 11.3v overnight. Either the battery was bad/not fully charged or you have a parasitic drain.

+1, you can actually run a true load test on the alternator with the correct equipment such as a battery load tester.

[ekstroemtj]

What's the voltage reading if you turn on the headlight, the a/c, and the rear defroster at the same time during idling? If it's below 13.5v, your alternator is likely bad. That's a crude load test before you can get the alternator tested properly at the shop.

Have you tried to test for battery drain after car is locked? One of your posts said the battery dropped to 11.3v overnight. Either the battery was bad/not fully charged or you have a parasitic drain.

Yes the battery was only 11.3 after some days the car was not moved at all. You are right, There is some drain for shure.

The high reading of 13.96 was with ac, headlight. Radio, defroster on.

[Ahsai]

In that case, you need to track down the drain first. Otherwise your battery will keep draining and alternator keeps stressing out recharging the depleted battery. Very bad for both the battery and the alternator.

If you still want to DIY, it will be quite involving. The easiest is to put a low current DC clamp meter on one of the battery cables to check for current drawn after you lock the car. This one is great http://www.amazon.com/685-Amps-Current-Probe-Frequency/dp/B000JFHMRA

This way you don't break the circuit and restart the electronic modules. Just wait for 1/2hr to 1hr and check the reading again after all modules have gone to sleep. If you see a drain of tens of mA or more, you need to check the fuses.

Edited March 29, 2014 by Ahsai

[ekstroemtj]

+1, you can actually run a true load test on the alternator with the correct equipment such as a battery load tester.

JFP .... I know i have to get it tested in a professional way. The only reason why i want to do some research by myself:

I know when i bring the car to the shop i will get it back with some parts changed and a bill which will be much more than 1000 Euro. My cayenne s was there many many times in the last 2 years and in total i spent 10.000 euro for changing parts and labour. Many of these service jobs where not neccessary i found out.

[JFP in PA]

+1, you can actually run a true load test on the alternator with the correct equipment such as a battery load tester.

JFP .... I know i have to get it tested in a professional way. The only reason why i want to do some research by myself:

I know when i bring the car to the shop i will get it back with some parts changed and a bill which will be much more than 1000 Euro. My cayenne s was there many many times in the last 2 years and in total i spent 10.000 euro for changing parts and labour. Many of these service jobs where not neccessary i found out.

If you can live with disconnecting the battery (loss of settings and DME data), you can use your volt meter set for mA between the positive cable and the battery; you should see 40-60mA. If you see more current draw than that, start pulling and then replacing the fuses one at a time until the current draw suddenly drops into that range. When that happens, you have isolated the fuse circuit that the parasitic draw is on.

[JFP in PA]

You could also buy a hand held load tester and test the alternator and battery yourself without any data loss or battery disconnect. Units sell on Amazon and elsewhere for as little as $45-65 US. Handy tool to own:

http://www.amazon.com/3181-Heavy-Duty-Battery-Load-Tester/dp/B000O3U2UQ/ref=sr_1_2/175-7444179-0003640?ie=UTF8&qid=1396133146&sr=8-2&keywords=battery+load+tester

[ekstroemtj]

GREAT GREAT . Thank you ! I will do this.

I keep you posted

[ekstroemtj]

Looking at the car today. No power drain. Starting not a problem at all .Driving normal. No battery warning signal. For me its like a miracle.

I remember what members here always recommand. Look at things or changings which you did lately.

The only thing i did:

I used a external navi system and charged it via power outlet. The charging cable was still plugged in yesterday. I removed it. And today the problem dissapeared. Maybe this was the reason? I will see.

By the way, with my cayenne s i had random PSM problems. In the end i found out, most of these problems appeared when i used a aftermarket charging cable for my iphone. I believe there is a relation between using power outlets and electric problems. I am dreaming or this could be possible?!

[Ahsai]

Very likely. Is your cigarette power outlet poweded at all times or power will be cut after some timeout after you lock the car?

[JFP in PA]

Looking at the car today. No power drain. Starting not a problem at all .Driving normal. No battery warning signal. For me its like a miracle.

I remember what members here always recommand. Look at things or changings which you did lately.

The only thing i did:

I used a external navi system and charged it via power outlet. The charging cable was still plugged in yesterday. I removed it. And today the problem dissapeared. Maybe this was the reason? I will see.

By the way, with my cayenne s i had random PSM problems. In the end i found out, most of these problems appeared when i used a aftermarket charging cable for my iphone. I believe there is a relation between using power outlets and electric problems. I am dreaming or this could be possible?!

Yes, they can be related. You car's lighter socket is hot at all times so it can be used to plug a battery maintainer into it. Both your nav unit and your iPhone chargers are "hot at all times when plugged in, so they are large parasitic draw items, even when the devices they power are not in the car. Both your ABS and PSM systems are hyper sensitive to voltage fluctuations, quite often when we get a customer's car in with the ABS and PSM MIL lights on, it turns out to be an electrical system problem (corroded cables, weak battery, bad alternator).

[ekstroemtj]

Its not the lighter socket which i used for charging device.

I used on of the sockets which are in the car. Footwell, backside of the armrest, There are many of them.

But as mentioned before, there must be some relation betwenn this electric gramlins and the sockets.

Do i have to get them tested in some way or is the best advice: dont use it.

Thank you to everybody for supporting me !

Donation is on the way:-)

[Ahsai]

Whatever socketas you use, as long as they are hot at all times, they are always connected to the battery and will drain it like John said.

I highly recommand this tester that plugs in the cig outlet so you can see the voltage through the car windows when you walk up to your car before unlocking it. It uses negligible power so it won't drain your battery even left plugged in at all times.

http://www.amazon.com/gp/aw/d/B000EVWDU0/ref=mp_s_a_1_29?qid=1396214198&sr=8-29π=SY200_QL40

It also tests your battery and alternator.

[ekstroemtj]

I will order it. Looks like a very useful tool.

Thank you!

[Ahsai]

I will order it. Looks like a very useful tool.

Thank you!

Great. Don't let its low price fool you. It's calibrated and very precise. It measures voltage to 2 decimal places (I verified with a very accurate Fluke multimeter). It lets you read the voltage before you unlock the car. That's important because once unlocked, all the interior lights and electronic modules start to draw current so you can't get an accurate "at rest" voltage reading of the battery.

The "at rest" voltage tells you the state of charge of the battery 12.6v = fully charged, 12.3v = 50% charged, etc. With this, you can test the theory of your navi charger and other elect chargers draining the battery.

Also, you can read the instantaneous voltage when you crank, anything lower than 9.6v means your battery is weak.

When you turned on your elect consumers like a/c, headlights, heaters, etc, you can also read the voltage accurately. As mentioned before, 13.5-14.5v is normal.

For the price of a few cups of coffee, I'm blown away by its usefulness and quality.

[ekstroemtj]

Thank you very much for the explanation. Its ordered. I will report the test results when i get it.