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A993LAD
Nürburgring


Joined: 20 Mar 2007
Posts: 449
Location: Cambs


PostPosted: Thu Jul 27, 2017 12:11 pm    Post subject: trying to trace parasitic current draw Reply with quote

I'm still trying to track down a parasitic current draw which is causing starter problems if the car sits for more than a few days.

It looks like the current draw when the car is parked is around 60 mA. Would that be enough to drain the battery below a level that will turn the starter motor after 2 - 3 days.

I read somewhere that the current draw for a 993 should be less than 20mA but I also just watched a Youtube video where somebody was saying most modern cars regularly draw 60 - 100 mA.

The battery reads about 12.7 V after a run but is down to 12.1 after a few days. The battery is expensive and pretty new - about 1 year old.

I've tried pulling each of the 40 fuses in the main fuse box whilst the meter is connected but the current draw remains at 60mA. Are there other fuses or circuits I need to check if none of these fuses seem to affect the current draw?
 
  
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Tobesetc
Suzuka


Joined: 02 Jun 2014
Posts: 1207
Location: West London, UK


PostPosted: Thu Jul 27, 2017 12:35 pm    Post subject: Reply with quote

I'll start what will be a long list of possibilities with two that happened to my C4...

Alarm siren battery was worn out and no longer retained charge, meaning that it constantly needed to be topped up. (It's now on eBay)

My Climate Control Unit failed in some convoluted way, meaning that it would sporadically fire various parts of the system even when the ignition was off.

Good luck - it's a right Julian Clary trying to locate these sort of faults.
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Trantorman
Spa-Francorchamps


Joined: 04 Aug 2008
Posts: 297



PostPosted: Thu Jul 27, 2017 1:14 pm    Post subject: Reply with quote

two very likely options:

Old tracker, often the old ones were mounted close to where the first aid kit was screwed onto the metal panel work then covered in foil tape. often wired into the relays in the front compartment next to the spare wheel.

modern units are much smaller and easier to install better hidden.

or has been suggested your alarm siren battery is dead, try disconnection the siren and see if that helps.

Neither of the above cause would be found by pulling fuses, the CCU draw should be found by pulling the right fuse.

Have a look on Tore b's sight, he has good fault finding info on it for the CCU.


Good luck
 
  
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A993LAD
Nürburgring


Joined: 20 Mar 2007
Posts: 449
Location: Cambs


PostPosted: Thu Jul 27, 2017 2:05 pm    Post subject: Reply with quote

Thanks guys

I'm pretty confident there is no tracker on my car .

The ccu was sent off to Torre and refurbished and sent back with a clean bill of health so hopefully that should be okay

There is an alarm siren in the engine compartment and I had no idea he had its own battery so I'll try disconnecting that
 
  
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Allan E
Newbie


Joined: 17 Jun 2017
Posts: 36
Location: North-East England


PostPosted: Thu Jul 27, 2017 2:53 pm    Post subject: Alarm Siren Reply with quote

Is this the alarm siren mentioned? located in rear near side wing area (approx 100mm square box) It was not connected in my car but the wiring is still present, two push-in connectors. I have since removed the unit, no idea if it actually works!
 



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Allan E
Newbie


Joined: 17 Jun 2017
Posts: 36
Location: North-East England


PostPosted: Thu Jul 27, 2017 2:57 pm    Post subject: Battery draw Reply with quote

A993LAD wrote:
Thanks guys

I'm pretty confident there is no tracker on my car .

The ccu was sent off to Torre and refurbished and sent back with a clean bill of health so hopefully that should be okay

There is an alarm siren in the engine compartment and I had no idea he had its own battery so I'll try disconnecting that


Consider a battery immobiser, bit of a pain having to reset the clock but if it saves the starting hassle job done.
 
  
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harryk
Spa-Francorchamps


Joined: 24 May 2007
Posts: 332
Location: N.Ireland


PostPosted: Thu Jul 27, 2017 3:27 pm    Post subject: Reply with quote

Does your car have an obc? A duff resistor in my lcd display left it permanently lit and was the cause of my problem.
_________________
1995 993 C4 Coupe. Schwartz/Flamenco Red soft nappa leather. Exclusive leather everything, Exclusive extended centre console, MO33 suspension set up by CG, FDM Goldenrod & SSK, Techart exhaust, Techart pedal set, Tequipment dials, Tequipment handbrake & gearlever.
 
  
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A993LAD
Nürburgring


Joined: 20 Mar 2007
Posts: 449
Location: Cambs


PostPosted: Thu Jul 27, 2017 4:34 pm    Post subject: Reply with quote

Thanks for the additional tips

My car doesn't have an OBC

And I've just ripped the siren out of the Engine bay and disconnected the wires that went to it

The car is still drawing 60 mA from the battery though

What next guys ?

And does anybody have a view on whether 60 mA is too much .
 
  
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Endoman
Imola


Joined: 11 Apr 2011
Posts: 781
Location: Bolton U.K.


PostPosted: Thu Jul 27, 2017 7:37 pm    Post subject: Reply with quote

Same prob. was traced to a faulty door swtich contact.
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Demort
Paul Ricard


Joined: 21 Mar 2015
Posts: 3105
Location: Sussex


PostPosted: Thu Jul 27, 2017 7:53 pm    Post subject: Reply with quote

60 milliamps = 0.06 of an amp .. thats not a drain .. thats pretty much normal for a car with a clock , radio and an alarm system .

You could try unplugging the radio if you want .

I would check the charge rate , the battery condition and is the car used on short journeys as the drain seems far to low to me to flatten a battery in 2 days .

You may well have a starter motor issue or lead which is over drawing current and so giving the syptoms of a flat battery .. but you dont have a drain .
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madalaa
Yas Marina


Joined: 13 Mar 2008
Posts: 8759
Location: West London

1995 Porsche 993 Carrera 4

PostPosted: Thu Jul 27, 2017 11:57 pm    Post subject: Reply with quote

How old is your battery? ........ might be worth changing it ........ my car at one point was "eating" batteries ....... but after I had a defunct tracker ripped out ....... also it had two alarm systems fitted ........ one factory and the other after market ..... all ripped out and started again which made life one helluva lot more easy.

Good luck ....... I daresay it will be a "duh" moment when you find the problem ...... Smile
 
  
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HomersSpiceRack
Newbie


Joined: 02 Apr 2017
Posts: 19



PostPosted: Fri Jul 28, 2017 12:22 am    Post subject: Reply with quote

Odd time of the year for the battery to struggle but I would start there.

Second we all use our cars regularly but we sometimes forget how infrequent those regular drives are and I would agree with Allen E and fit a battery isolator.

I use the £3 ones on eBay and all other outlets that take 3 mins to fit on the neg baterry terminal and can then isolate or connect the battery by a quarter turn. They are great 👍
 
  
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HomersSpiceRack
Newbie


Joined: 02 Apr 2017
Posts: 19



PostPosted: Fri Jul 28, 2017 12:24 am    Post subject: Reply with quote

 
  
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HomersSpiceRack
Newbie


Joined: 02 Apr 2017
Posts: 19



PostPosted: Fri Jul 28, 2017 12:27 am    Post subject: Reply with quote

Did I really say battery!

Dont know
 
  
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ToreB
Approved Trader


Joined: 13 May 2010
Posts: 526
Location: Oslo, Norway


PostPosted: Fri Jul 28, 2017 6:25 am    Post subject: Reply with quote

I would consider 60mA close to normal in a UK car, all cars were fitted with a HP alarm system. About half is normal in cars with no aftermarket equipment. (25-30mA) However, be sure to measure the current in a proper way:
https://www.bergvillfx.com/porsche-964-993-battery-current-measurements/

Cheers,
Tore
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Bergvill F/X
Porsche electronics specialists, products and repair services.
 
  
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ballcock
Sepang


Joined: 22 Jul 2008
Posts: 2815
Location: Dublin

1996 Porsche 993 Carrera 2

PostPosted: Sat Jul 29, 2017 10:23 am    Post subject: Reply with quote

Check to see if the windows are powered with key out of the ignition .. they should work doors open but the feed should be cut off when doors are closed.
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'83 W460 LWB G Wagen updated with OM602 engine and 6 speed 'box ...My daily driver

Ex. '99 996 C2 manual coupe.
 
  
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A993LAD
Nürburgring


Joined: 20 Mar 2007
Posts: 449
Location: Cambs


PostPosted: Mon Aug 14, 2017 1:20 pm    Post subject: Reply with quote

Hi all,

A quick update on this just in case it helps others in future, as the problem has been solved.

IT WAS THE BLOODY BATTERY!!! Which had failed.

So having checked, double checked, triple checked the current drain and replaced the earth strap, it turns out it was the battery that had failed all along, and it could not hold a charge for any period of time.

The reason I thought this was unlikely is because I bought the battery only one year ago and it was a high spec, high cost (certainly in terms of Halfords stock at the time) Yuasa 75 Ah Lifetime guarantee model.

If I started the car on a mains booster you could then drive it around all day and it always had enough charge to start again without any problem for the rest of the day. But you only had to leave the car overnight and the voltage would drop to 12.2 V and it didn't have enough power to start the car again. If left for three days the voltage drop to 11.5 V.

Annoyingly I started the car with the booster and drove it to Halfords and explained my problem seeking a replacement under the lifetime guarantee. But they came out to the car, put their official Yuasa test meter on the battery, and pronounced it was fine. I tried to explain that that was because my very efficient alternator had been charging it up for the last 10 miles, but it was highly unlikely it would start the car the following morning if I drove it home. They refused to accept that the battery had a problem if their "£2,000 testmeter" said it was okay. I foolishly spent 10 minutes trying to reason with them on what possible benefit I could get by changing one good battery for another good battery and therefore why would I waste my Sunday afternoon pursuing such a course of action. But they refused to be convinced and I had to return home with the faulty battery.

I just left the battery on the car for a week, by which time it was down to 11 V. I put another battery on the car temporarily and took the faulty one back and carried it into the shop where they replaced it without quibble.

The new battery is now on the car and I just got back from a week's holiday and the car started perfectly having sat idle whilst I was away.

So it turns out I didn't have an exceptional parasitic current draw at all and as suggested here 60mA draw is fine if your battery is in good condition.

Many thanks to all those that made suggestions
 
  
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