Battery drain issue
Thread Starter
Intermediate
Joined: Sep 2016
Posts: 37
Likes: 1
Really confused now,
followed the tests on the page he page you listed and all looks good:
test 1: 0.05v
test 2: 0.4v
test 3 and 4 could not be done due to there not being the +be jump terminal in the engine bay on the 997. How else can I do this test? I have looked at the +be terminal in the fuse box in foot well and this is strange but seems to be ground and has 60ohms between this and 0v of battery.
test 5: 14.1v which says my alternator is good?
i have a 0.25A drain on battery which is normal but still have starting issues after leaving it for 2 days?
really confused now :/
followed the tests on the page he page you listed and all looks good:
test 1: 0.05v
test 2: 0.4v
test 3 and 4 could not be done due to there not being the +be jump terminal in the engine bay on the 997. How else can I do this test? I have looked at the +be terminal in the fuse box in foot well and this is strange but seems to be ground and has 60ohms between this and 0v of battery.
test 5: 14.1v which says my alternator is good?
i have a 0.25A drain on battery which is normal but still have starting issues after leaving it for 2 days?
really confused now :/
I assume the 12.9v was measured at the battery (best case)? If it was measured at the back of the alternator, then the alternator is bad.
They are just 3 steps away from identifying the culprit.
1) Measure the voltage directly at the back of the alternator (with some load such as low beam and a/c ON). it should read ~14 to 14.5v
2) Measure the voltage drop between the back of the alternator output and the battery positive post
3) Measure the voltage drop between the alternator case and the battery negative post
You cannot measure the resistance of the cable directly with a regular multimeter because the resistance is so low. Bad cables will show up in 2) and 3) if they see >0.5v drop.
I know that for 996 (most likely for 997-1 too) the voltage at the battery should be 13.5v to 14.1v (with low beam and a/c ON) and engine fully warmed up. At the back of the alternator, it should be 13.5v to 14v.
See more comprehensive test cases here http://www.renntech.org/forums/topic...comment-260718
They are just 3 steps away from identifying the culprit.
1) Measure the voltage directly at the back of the alternator (with some load such as low beam and a/c ON). it should read ~14 to 14.5v
2) Measure the voltage drop between the back of the alternator output and the battery positive post
3) Measure the voltage drop between the alternator case and the battery negative post
You cannot measure the resistance of the cable directly with a regular multimeter because the resistance is so low. Bad cables will show up in 2) and 3) if they see >0.5v drop.
I know that for 996 (most likely for 997-1 too) the voltage at the battery should be 13.5v to 14.1v (with low beam and a/c ON) and engine fully warmed up. At the back of the alternator, it should be 13.5v to 14v.
See more comprehensive test cases here http://www.renntech.org/forums/topic...comment-260718
RL Community Team
Rennlist Member
Rennlist Member
Joined: Oct 2007
Posts: 28,544
Likes: 8,351
From: Clemson, SC
I'm no EE, but In this case, does voltage really matter? Shouldn't you just be looking at the amperage draw across a fuse or circuit when everything is turned off to find the culprit?
Nordschleife Master
Joined: May 2005
Posts: 7,326
Likes: 77
If the tests were done as prescribed such as warmed engine and low beam and a/c ON, your cables are fine, your alternator is a little bit low but not bad. What's killing your battery is the 250mA draw. Normal draw should be less than 50mA, depending on theboptions installed on the car. Some cars draw much less than that.
Seems to me you should focus on the parasitic drain.
Seems to me you should focus on the parasitic drain.
Really confused now,
followed the tests on the page he page you listed and all looks good:
test 1: 0.05v
test 2: 0.4v
test 3 and 4 could not be done due to there not being the +be jump terminal in the engine bay on the 997. How else can I do this test? I have looked at the +be terminal in the fuse box in foot well and this is strange but seems to be ground and has 60ohms between this and 0v of battery.
test 5: 14.1v which says my alternator is good?
i have a 0.25A drain on battery which is normal but still have starting issues after leaving it for 2 days?
really confused now :/
followed the tests on the page he page you listed and all looks good:
test 1: 0.05v
test 2: 0.4v
test 3 and 4 could not be done due to there not being the +be jump terminal in the engine bay on the 997. How else can I do this test? I have looked at the +be terminal in the fuse box in foot well and this is strange but seems to be ground and has 60ohms between this and 0v of battery.
test 5: 14.1v which says my alternator is good?
i have a 0.25A drain on battery which is normal but still have starting issues after leaving it for 2 days?
really confused now :/
Nordschleife Master
Joined: May 2005
Posts: 7,326
Likes: 77
The OP mentioned 12.9v measured (at the battery?) with and without load. That is quite low (ask any mechanics) hence the investigation of the alternator and the cables.
Thread Starter
Intermediate
Joined: Sep 2016
Posts: 37
Likes: 1
sorry for confusion, I have a battery drain of 0.05A not 0.25A. Is it possible to do tests 3 and 4 on the 997 as there is no +ve terminal or do I use the one in the fuse box?
Nordschleife Master
Joined: May 2005
Posts: 7,326
Likes: 77
Test 1 says your ground is good and has minimal voltage drop. Test2 says you lose 0.4v on the positive side. Your alternator measures 14.1v so you would expect about 13.5v at the battery. You also said the shop measured 12.9. Even though we can't compare these measurements directly as they were taken at different times seems you still have 0.5v unaccounted for between the alternator and the battery?
If your drain is truly 50mA, that's on the high side but not way out and definitely won't drain your battery enough to cause you starting issues in only 48hrs.
So things don't add up, literally.
Nordschleife Master
Joined: May 2005
Posts: 7,326
Likes: 77
Btw, this is a very handy and accurate tester I always recommend ppl. It has to be this one and not something that looks similar. It should help you in this case.
https://www.amazon.com/INNOVA-3721-B...ds=INNOVA+3721
https://www.amazon.com/INNOVA-3721-B...ds=INNOVA+3721
Last edited by Ahsai; Nov 7, 2016 at 05:02 PM.
Race Director
Joined: Apr 2010
Posts: 10,104
Likes: 485
From: Ny
OP,at this point it sounds like user error. By that I mean you're missing something when running the tests. You should take the car in to get it looked at by a Porsche specialist : either a trusty dealer or a well rated Porsche independent. They'll charge you 150-200$ the most but you'll know if there's a problem for sure,no guessing.
Just my 2c...
Just my 2c...
Rennlist Stories
The Best Porsche Posts for Porsche Enthusiasts
Porsche Reveals Coupe Variant of the Electric Cayenne With a Fresh Look
Verdad Gallardo
10 Porsche Colors That Have More Personality Than Most People
Verdad Gallardo
Guntherwerks' Final Speedster Creation Is the Ultimate Porsche Restomod
Verdad Gallardo
10 Reasons I Hate Going to the Porsche Dealership (& the 1 Reason I Stay)
Joe Kucinski
Porsche Shakes Up The Nürburgring Lap Record Table Once Again
Verdad Gallardo
6 Ways the Porsche 911 GT3 S/C Redefines Performance
Joe Kucinski
10 Wildest Homologation Specials Porsche Ever Sold
Verdad Gallardo
Super Rare RUF BTR III Comes Out of Hibernation, Looking For a New Home
Verdad Gallardo
10 Porsche Opinions That Can Start a Fight
Joe Kucinski
Racer
Joined: May 2011
Posts: 309
Likes: 18
From: North Carolina
OP,at this point it sounds like user error. By that I mean you're missing something when running the tests. You should take the car in to get it looked at by a Porsche specialist : either a trusty dealer or a well rated Porsche independent. They'll charge you 150-200$ the most but you'll know if there's a problem for sure,no guessing.
Just my 2c...
Just my 2c...
I realized after the harness actually finally arrived from Germany that the wire harness is one of the first items installed as the car is constructed. Warranty covered the expense and the guys did a great job. After all was said and done, I couldn't tell that they had been in my car, even though I know that it was gutted. The car is still going strong after another year plus and I am a very happy camper.
Another benefit I soon discovered is that even the PDK works better. I had a significant pause or delay in shifts sometimes (again intermittent) that caused me to feel that the tranny was not going to shift gears. Without an upgrade or software, the new wiring harness seemed to solve that problem too as it has not happened again since the harness was replaced.
Good Luck
Pro
Joined: Jun 2003
Posts: 730
Likes: 136
From: Findlay OH
amazon link did not work
Btw, this is a very handy and accurate tester I always recommend ppl. It has to be this one and not something that looks similar. It should help you in this case.
https://www.amazon.com/INNOVA-3721-B.../dp/B000EVWDU0
https://www.amazon.com/INNOVA-3721-B.../dp/B000EVWDU0
Nordschleife Master
Joined: May 2005
Posts: 7,326
Likes: 77
Please try this https://www.amazon.com/INNOVA-3721-B...ds=INNOVA+3721
If it still doesn't work, just search for INNOVA 3721. It's only ~$13.
If it still doesn't work, just search for INNOVA 3721. It's only ~$13.
Nordschleife Master
Joined: May 2005
Posts: 7,326
Likes: 77
See post#34 here for how to use the tester effectively.
https://rennlist.com/forums/996-foru...l#post12614785
https://rennlist.com/forums/996-foru...l#post12614785
1st Gear
Joined: Dec 2019
Posts: 1
Likes: 0
battery drain over night PORSCHE 997.1TT
AFTER SITTING IN MY CAR FOR AWHILE AFTER SHUT AND REMOVING THE KEY I HEAR MY RADIO CONTINUE MAKING A SOUND SIMILAR TO A CD EJECTING!! OVER AND OVER AND OVER! CERTAINLY ENOUGH TO KILL THE BATTERY OVERNITE!!! I HAVE TRIED MANY DIFFERENT WAYS OF LOCKING IT OR NOT LOCKING IT. IT WON"T STOP CYCLING AND KILLING THE BATTERY. HELP!!
Rennlist Member
Joined: Apr 2007
Posts: 1,578
Likes: 84
My Porsche tech thinks the long battery cable in my car needs to go. I was sure the PO replaced it already at RUF along with alternator at 82k mi.
My dash or PCM has a soft rapid clicking that sounds like a teletype machine tapping out a message or Morse code.
I have a QR with a Momo 69 wheel in the car and if the noise starts up, I remove the wheel and get up close to the gauge cluster to listen.
I am 99% sure it's coming from the PCM. Not really sure when it started as the stereo cover up the noise. I chalk it up to a dying PCM.....I do have battery drain but i drive the car daily in short hops most of the time and some 30-40mi highway runs maybe 2-3x/wk.
Battery stats:
RED Optima battery maybe 2 yrs old max.
Using the Innova plug in meter Aloha refers to:
12.250v hit unlock drops it to 12.15-26v sitting before start up.
9.9v during crank.
13.9v driving.
12.41v after a 2 mi quick coffee run then home, lock doors, watch meter as car slumbers.
I do not lock the car in the garage ever. The numbers above reflect my charging the battery fully yesterday with the Porsche branded charger.
My dash or PCM has a soft rapid clicking that sounds like a teletype machine tapping out a message or Morse code.
I have a QR with a Momo 69 wheel in the car and if the noise starts up, I remove the wheel and get up close to the gauge cluster to listen.
I am 99% sure it's coming from the PCM. Not really sure when it started as the stereo cover up the noise. I chalk it up to a dying PCM.....I do have battery drain but i drive the car daily in short hops most of the time and some 30-40mi highway runs maybe 2-3x/wk.
Battery stats:
RED Optima battery maybe 2 yrs old max.
Using the Innova plug in meter Aloha refers to:
12.250v hit unlock drops it to 12.15-26v sitting before start up.
9.9v during crank.
13.9v driving.
12.41v after a 2 mi quick coffee run then home, lock doors, watch meter as car slumbers.
I do not lock the car in the garage ever. The numbers above reflect my charging the battery fully yesterday with the Porsche branded charger.
Last edited by ALEV8; Dec 19, 2019 at 03:50 PM.
3rd Gear
Joined: Feb 2021
Posts: 3
Likes: 0
Hello All, New here, glad i found this forum
2010 Carerra S with 24000 Miles, hardly driven... purchased new battery from AAA 6 months ago, this thing dies overnight. had a porsche auto shop do a diagnostic and they tested the battery and alternator and its all good. was told i may have a parasitic draw and to find it they charge $175 an hour with no guarantee how many hours it will take to find the problem. i see many here have had this issue, what has worked for you? thx in advance
2010 Carerra S with 24000 Miles, hardly driven... purchased new battery from AAA 6 months ago, this thing dies overnight. had a porsche auto shop do a diagnostic and they tested the battery and alternator and its all good. was told i may have a parasitic draw and to find it they charge $175 an hour with no guarantee how many hours it will take to find the problem. i see many here have had this issue, what has worked for you? thx in advance