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desilran

Battery 5A drain every 45mins

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2003 Boxster S, 6 speed, RHD

 

My car is often not driven for a week or two weeks and recently the battery died.  As it was an old battery I replaced it with a new one, charged up via the mains.  In two weeks the battery had died again.  Took it into mechanics who said that there was a 5A drain every 45 mins.

 

It does have an aftermarket stereo but that has been in place for too long to be the cause of this.

 

I also noticed recently that the roof mechanism will not close all the way unless I toggle the switch open and close until it finally closes to the point where I can activate the manual lever.

 

Also the glove box wasn't closing properly and so the alarm was not activating - I have managed to force the switch to close now so the alarm works.  

 

Any ideas on what could be drawing that kind of power every 45 mins?  

 

Thanks

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The regularity of the drain is odd. Do you have a tracking device fitted and, if so, what does that hook up to?

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Hi Wizard,

Nope - no tracking device fitted.  Nothing has fundamentally changed in the last year, apart from that I am driving the car a lot less now than I was before.  It could be that by driving it more previously I was hiding the drain, but I have left it for a couple of weeks without an issue.  Now if the car is left unused for a week the battery is totally dead.

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Hi.

 

Perplexing. I'd fully charge the battery, let it stand for an hour, take a voltage reading on the battery, pull the aftermarket stereo fuse, leave it a couple of days and then take another voltage reading.

 

I have the 2.7 from the same year. Not a daily driver by any means. My heavy parasitic drain some years back turned out to be ignition switch related ..... an easy and inexpensive fix, with the part coming from Audi if I recall correctly. The alternator regulator had been suggested as the most likely culprit.

 

 

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The standard procedure to track down parasitic voltage draws is to place a multi meter between the positive battery cable and the battery, set on ohms.  Then start pulling fuses one at a time until you find the circuit that is creating the draw.

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My guess is the mechanic has a way to log/monitor the periodic current drain. I bet he was not sitting there and staring at the DMM for hrs and hrs just to catch the event every 45min.

 

If true I would disconnect all the aftermarket devices and remove all the fuses. Then every hr add back half of fuses. With some luck, you should be able the narrow down the drain to half of the fuses. Repeat the same on the half that causes the drain.

 

This is assuming the source of the drain behaves after powered cycle and it gets power from one of the fuses.

Edited by Ahsai
  • Upvote 1

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Check drain using a meter.

If you need the door open close the latch so that it thinks the door is closed.

 

 

 

 

Sent from my iPhone using Tapatalk

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Looking at this another way the 5A drain every 45 mins is equivalent to 6.66 A/hr.

This is a power drain of 6.66A X 12V  =  80 watts/hr.   

This is like having all your running lights (both front sides and rears (20w)) on for 4 hours, or all your lights (running and dipped) on for about an hour. That's a substantial drain and enough to cause a decent fire if it's the result of a short circuit or poor connection.

 

I had a drain on a vehicle recently that was caused by a poor spade connection in a fuse holder.  Heat was being generated which caused the plastic in the fuse holder to melt and enough heat to distort a nearby plastic shield.    

 

The advice you have had about isolating the source is very sound.  The other way to track the source is to charge up the battery. Leave it settle for about 30 mins and check the voltage.  Start removing fuses and see if the voltage rises. If you remove a load the voltage will rise slightly. This will give you a clue as to where the leakage might be located. 

 

 

 

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8 hours ago, JFP in PA said:

The standard procedure to track down parasitic voltage draws is to place a multi meter between the positive battery cable and the battery, set on ohms.  Then start pulling fuses one at a time until you find the circuit that is creating the draw.

This approach is incorrect and you will most likely burn out the meter if you do this.  First of all, it is parasitic CURRENT draws (not voltage), Secondly, you should set the meter on Amps (e.g. current) NOT OHMS.  While the general idea is correct (after the corrections I made) you need to be aware of important details: As a general rule of thumb, the maximum current draw with everything in the car 'turned off' and having waited about 60 seconds for all the devices to go to sleep, is 50 ma (or 0.050 A).  Opening a door which will cause interior lights to go on and 'awaken' a factory alarm box will result in a current draw of roughly 2-6 amps (depending on all the loads).  Point is, your meter should be able to autorange OR, set it to the high range and then wait a minute till the current draw settles down. then switch to the low range to see the actual draw.

The fuse-pull method has to be well organized but looking at the fuse layout and begin pulling fuses one at a time and note the change in current draw, One must wait as long as 30-45 seconds for the reading to settle.Likewise, one must wait 30-45 seconds after reinserting the fuse and moving to the next one.  It is very helpful to record the current changes associated with each fuse. 

 

5 amps is a hefty current draw for a vehicle 'at rest'.  This means a 'large load' is being connected to the supply bus.  Typically, this includes the ignition switch, and the starter motor.   If the ignition switch is faulty, it could be energizing a number of loads.  Relays that engage the starter motor circuit or the starter motor itself could be (partially) shorted, but this is unlikely.  When in the 'off' condition, the radio should draw no more than about 20 ma to run the clock ckt.  Generally, alarm monitoring is around 10ma. 

Sources of problems also include: trunk lights that are kept on due to faulty trunk lid switches, and shorted wiper motors (if their power feed bypasses the ignition switch). 

 

The numbers above are general 'ball park' numbers, not Porsche specific.  The FSM would have the real numbers.  I based my numbers on troubleshooting similar problems on my jeep and Saab. 

Good luck

J

 

 

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12 hours ago, desilran said:

2003 Boxster S, 6 speed, RHD

 

My car is often not driven for a week or two weeks and recently the battery died.  As it was an old battery I replaced it with a new one, charged up via the mains.  In two weeks the battery had died again.  Took it into mechanics who said that there was a 5A drain every 45 mins.

 

It does have an aftermarket stereo but that has been in place for too long to be the cause of this.

 

I also noticed recently that the roof mechanism will not close all the way unless I toggle the switch open and close until it finally closes to the point where I can activate the manual lever.

 

Also the glove box wasn't closing properly and so the alarm was not activating - I have managed to force the switch to close now so the alarm works.  

 

Any ideas on what could be drawing that kind of power every 45 mins?  

 

Thanks

After re-reading the post, the drain interval/pattern is *very* strange.  With all due respect, is this the correct story??  every 45 mins the current draw shoots up to 5 Amps  (from what? and for how long?)???  I know of nothing in a vehicle that would run at this frequency or multiples of that frequency or that has  any similar behavior.   There are DMMs that are capable of monitoring readings over a period of time. You may need to get one if this is truly the case.  I'd start with the  monitoring the battery current draw and if it is over the normal value, start pulling & replacing fuses..

If the battery current is less than the normal value, then you may need a meter that monitors the current over time.

Good luck

J

 

 

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This Post appears on several other Forums (with different monikers)where most help generously offered was ignored or not understood.

As other posts indicate ,flailing with the sensitive electrics without the manual and the DMM and automotive knowledge is leading the Poster into a potential expensive mistake. There are lots of competent ,honest Auto Electricians in  city the size of London who would charge 10-20 minutes of Diagnostic time to identify the cause of the fault. Why not use them instead of signing up for several Forums and getting people literally all over the world to speculate on partial(t best !) information? Why not ask on a U.K. Forum for a referral to an Indie? Or at least indicate a generic Parasitic Drain test has been done - plenty on Youtube.

Edited by Schnell Gelb

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This problem sounds quite unique and interesting. It's not clear to me the poster intends to perform any trouble shooting himself. The difficulty seems to be catching the drain in action. It sounds like the mechanic had some monitoring/logging device that logs the drain ON and OFF periods (i.e., duty cycle). If the drain was constant or lasted somewhat long enough, I would think the mechanic would have narrowed it down already.

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Thanks all for your advice and opinions. As Schnell points out I have posted this query on a number of sites. Furthermore I am new to using forums for assistance. My view was that someone might have experienced this already hence broadening my search onto a number of forums. 

  @Schnell - your harsh response and clear lack of sympathy for a noob trying to get information via forums is both unhelpful and misleading. I am taking on board all the good advice prior to working out a plan of action. Your comments simply waste everyone's time. 

As I say - thanks for everyone's helpful advice and when I identify the issue I'll let you know. 

Cheers 

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On 3/31/2017 at 5:50 AM, desilran said:

Thanks all for your advice and opinions. As Schnell points out I have posted this query on a number of sites. Furthermore I am new to using forums for assistance. My view was that someone might have experienced this already hence broadening my search onto a number of forums. 

  @Schnell - your harsh response and clear lack of sympathy for a noob trying to get information via forums is both unhelpful and misleading. I am taking on board all the good advice prior to working out a plan of action. Your comments simply waste everyone's time. 

As I say - thanks for everyone's helpful advice and when I identify the issue I'll let you know. 

Cheers 

I am sorry your feelings were hurt.

You were given advice,and asked questions .You did not respond. THAT is what wastes our efforts to help you. People in this Thread are now repeating questions to you because you haven't answered. Our first obligation is to do no harm.Hence my recommendation to use an Auto Electrician since you lack the FSM(or alternative) and a high amp  DMM. Which is why I recommended you spend 10 -20 minutes of Diagnostic time with an Auto Electrician. You have a huge current draw but no blown fuses. That is potentially dangerous.Maybe someone put a high amp fuse where there should be a low amp one? You haven't mentioned using the Fuse Legend !.And btw I have literally thousands of Posts under various names on multiple Porsche Forums helping people -particularly those who answer our questions and respond.It is considered good Forum etiquette.

Please understand we can't mind read or diagnose your DME or electrical connections remotely.It is just speculation w/o the facts.You need to help us by responding to specific questions. The smarter people on the Forums just won't even participate when they see Posts like yours, so help yourself - answer the questions so we can help you. Sympathy won't fix your problem.But answers to our questions might.

Edited by Schnell Gelb
  • Upvote 1

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I imagine that you'll already have guessed that my earlier suggestion to let the battery drain for a couple of days should have read a couple of hours.

 

Old age comes to us all ;-)

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@Wizard - lol I'm getting the car back today and will work through the various steps as advised.  Hopefully I can identify the drain and solve the problem!

 

thanks for all your help,

 

Edited by desilran

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The drain table is invaluable in trouble shooting this problem.  In addition, IMHO, getting the wiring diagrams would be very helpful.  Assuming you have some good understanding of electrical circuit theory and devices, it would be helpful to study the wiring diagrams to understand which loads are being isolated when you pull fuses as there are multiple devices on each leg.  Pulling fuses, generally, will narrow down the circuit but not the device that is causing the problem. Well, in some cases the fuse description will point to an obvious device which you could isolate but that may not solve the problem.

 

After reading through the drain table, prepare to spend some time doing this.  I was *really* surprised to see a wait time of over one hour to get to the smallest current draw. 

Have fun

 

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Not an expert on this, but after the old battery died, I replaced with an Interstate AGM battery.  No issues since.

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Hi All,


Firstly thank you for all your suggestions, information and ideas.  I eventually managed to resolve the drain issue by changing out the ignition switch.  This is a fairly easy procedure and well documented online.  Since changing the switch everything seems to have resumed normal function and the battery is now no longer being drained!  

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