87 Carrera nagging electrical problem
11-06-2009, 01:06 PM
#16
Team Owner
the drain has nothing to do with the battery .. total coincidence. you will NOT have a curent flow ( drain) if you do not have a path to ground. keep looking .. thnk you have moved soemthing that is causing your drain .. having said that I wouod have though even 30ma would take a good battery quite a while to drain .. mine is a 7ma drain ..
11-16-2009, 02:32 PM
#17
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Thanks
Iceman, which car. A 78SC is a different animal than a 87 Carrera.
Drain now at 24MA.
When I remove the three heavy red wires from the (+) terminal I get down to a lot less. There are three of them. One is "0" ma. I haven't figured out where those wires go yet but I have more testing to do. Ran into a snag. my brake lights are out. Traced to two bad switches on the master cylinder. On order.
Any 87 Carrera's out there who have measured battery drain and remember the numbers? Each model year must be different due to the configuration of computers, sensors, types of clock mechanism, radio type, relays ... etc.
Iceman, which car. A 78SC is a different animal than a 87 Carrera.
Drain now at 24MA.
When I remove the three heavy red wires from the (+) terminal I get down to a lot less. There are three of them. One is "0" ma. I haven't figured out where those wires go yet but I have more testing to do. Ran into a snag. my brake lights are out. Traced to two bad switches on the master cylinder. On order.
Any 87 Carrera's out there who have measured battery drain and remember the numbers? Each model year must be different due to the configuration of computers, sensors, types of clock mechanism, radio type, relays ... etc.
11-16-2009, 07:24 PM
#19
Team Owner
yes mine was an SC .. so just the clock .. but I can't imagine 24ma would drain your battery dead !!
Sounds like you are making progress though ... One of the biggies goes to the starter motor , another to the alternator .. one probably to the fuse block , but I am just guessing..
Sounds like you are making progress though ... One of the biggies goes to the starter motor , another to the alternator .. one probably to the fuse block , but I am just guessing..
11-16-2009, 07:55 PM
#20
I haddah Google dat
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I just checked mine in the parking lot with my El Cheapo hardware store mulitmeter that I keep in the front trunk for emergencies. I barely trust this device, but it read 26.2 ma. I'll check it with my good one when I get home.
Remember to disable the front trunk light. I will do that when I get home and try it again. If mine is 26 ma, then it's not draining the battery.
Remember to disable the front trunk light. I will do that when I get home and try it again. If mine is 26 ma, then it's not draining the battery.
11-17-2009, 11:39 AM
#22
"The reading is pulsing at a rate about as fast as you can say one, two, three, four ......"
Yes, that typically is caused by the analog Porsche clocks.
Any current draw less than 60ma will easily last over two weeks:
Typical battery - 60 Amp-Hr
For 1/2 capacity to start - 30 Amp-hr
Days = 30 /.06 /24 ~ = 20 days
Yes, that typically is caused by the analog Porsche clocks.
Any current draw less than 60ma will easily last over two weeks:
Typical battery - 60 Amp-Hr
For 1/2 capacity to start - 30 Amp-hr
Days = 30 /.06 /24 ~ = 20 days
11-18-2009, 05:19 PM
#23
Rennlist Member
"The reading is pulsing at a rate about as fast as you can say one, two, three, four ......"
Yes, that typically is caused by the analog Porsche clocks.
Any current draw less than 60ma will easily last over two weeks:
Typical battery - 60 Amp-Hr
For 1/2 capacity to start - 30 Amp-hr
Days = 30 /.06 /24 ~ = 20 days
Yes, that typically is caused by the analog Porsche clocks.
Any current draw less than 60ma will easily last over two weeks:
Typical battery - 60 Amp-Hr
For 1/2 capacity to start - 30 Amp-hr
Days = 30 /.06 /24 ~ = 20 days
Loren: whatzup these days?
Best,
Doyle
11-18-2009, 06:51 PM
#24
Race Car
If a 12 volt battery reads 11 volts at anytime, the battery is DEAD. very very rarely will a battery come back from such a problem but it is internally shorting on one of the 6 cells. This is an intermittant symptom, but the most common failure mode for a battery. Warrenty the battery before you do anymore. But get rid of the aftermarket alarm and any excesive stereo at a qualified Porsche shop so they know how to put it back together properly.
11-18-2009, 08:23 PM
#25
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Catch up. 
This one reads now between 24ma and 26.6,.9 back to 24 in about as much time as you can count. So I guess without the Alpine security system the car is back to normal that way.
Now to follow on what whalebird discussed. Interesting.
After sitting a few days the battery read 11.4V on my digital voltage cigarette lighter instrument. Once started the reading was well into the 13.5v +. Then, while on a test drive, without rhyme or reason, the voltmeter began to wind down from 13.5V to 12V, then it started back up again. Took more than several minutes to wind down and about as much time to go back to normal. Turning on the headlights had no effect. Bad battery?
This one reads now between 24ma and 26.6,.9 back to 24 in about as much time as you can count. So I guess without the Alpine security system the car is back to normal that way.Now to follow on what whalebird discussed. Interesting.
After sitting a few days the battery read 11.4V on my digital voltage cigarette lighter instrument. Once started the reading was well into the 13.5v +. Then, while on a test drive, without rhyme or reason, the voltmeter began to wind down from 13.5V to 12V, then it started back up again. Took more than several minutes to wind down and about as much time to go back to normal. Turning on the headlights had no effect. Bad battery?
11-19-2009, 09:22 AM
#26
Race Car
Yup. bad battery. It has an internal short which can kill one of the 6 cells. It comes and goes with temperature/voltage input/load and vibration. This is common on batteries that someone just added water too because often they will wash a conductive impurity into the lead plates that shorts out the voltage on that cell. However, new batteries have upwards of a 40% failure rate. I have posted before my experiance on batteries, but I will sum up - In Porsche Factory training(I'm a Porsche Factory tech)they told us on the first day of my first training course "every automobile repair starts with the battery terminals". If the brakes squeek - make sure it has proper voltage and connections. It sounds overkill, but the point was that we should get in the habit of checking battery condition/connection on every car. I got into this habit and was alarmed at how many cars had bad connections/batteries. A quick test with a volt meter was usually all it required and if I didn't see, at least 12 volts, there was a problem.
11-19-2009, 05:25 PM
#28
Rennlist Member
Yup. bad battery. It has an internal short which can kill one of the 6 cells. It comes and goes with temperature/voltage input/load and vibration. This is common on batteries that someone just added water too because often they will wash a conductive impurity into the lead plates that shorts out the voltage on that cell. However, new batteries have upwards of a 40% failure rate. I have posted before my experiance on batteries, but I will sum up - In Porsche Factory training(I'm a Porsche Factory tech)they told us on the first day of my first training course "every automobile repair starts with the battery terminals". If the brakes squeek - make sure it has proper voltage and connections. It sounds overkill, but the point was that we should get in the habit of checking battery condition/connection on every car. I got into this habit and was alarmed at how many cars had bad connections/batteries. A quick test with a volt meter was usually all it required and if I didn't see, at least 12 volts, there was a problem.
