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Albionmuz
Montreal


Joined: 28 Oct 2016
Posts: 594
Location: West Sussex


PostPosted: Thu Dec 20, 2018 12:46 pm    Post subject: Battery life when car is left unused Reply with quote

My 993 seems to discharge to the point where the car just doesn’t want to turn over properly after 3 weeks (in the winter). Is this normal?

Car is going to become a garage queen this weekend so will be on a charger in a garage for the next few months, so the problem will go away.

Just curious as my other cars retain their charge much better at this time of year. Battery is only about 3 years old and holds it’s charge well when used regularly.
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Sutton
Spa-Francorchamps


Joined: 04 Mar 2009
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PostPosted: Thu Dec 20, 2018 1:46 pm    Post subject: Reply with quote

That's my experience as well. My Ctek has come in handy.
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asterix_the_gaul
Barcelona


Joined: 20 Dec 2008
Posts: 1273
Location: Cheshire

1999 Porsche 996 Carrera 2

PostPosted: Thu Dec 20, 2018 1:56 pm    Post subject: Reply with quote

3 weeks is pretty good going, the more you let it go flat the shorter that time will get as the battery gently dies. A smart charger is the answer if it's not getting used.
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jev911uk
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Joined: 06 Mar 2011
Posts: 51
Location: Berkshire


PostPosted: Thu Dec 20, 2018 3:00 pm    Post subject: Reply with quote

Lots of stuff on a 993 that can be causing a parasitic drain, have a look through this DIY and see if you can tick some off:

https://www.bergvillfx.com/porsche-964-993-battery-current-measurements/
 
  
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Allan E
Silverstone


Joined: 17 Jun 2017
Posts: 144
Location: Rowlands Gill, Tyne & Wear


PostPosted: Thu Dec 20, 2018 3:44 pm    Post subject: Battery life Reply with quote

Definitely a smart charger is the way to go, I personally removed the bulb from the frunk light, offers no real light to the frunk. It also means when the conditioner is connected no worries about leaving the bonnet ajar.
For convenience I have my battery conditioner connected with push in wire fittings, much safer than crocodile clips on the battery posts.
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Albionmuz
Montreal


Joined: 28 Oct 2016
Posts: 594
Location: West Sussex


PostPosted: Thu Dec 20, 2018 4:01 pm    Post subject: Reply with quote

Yeah I have a Ctek with a permanent 1 click connector to the battery but the car has been on my drive whilst I was away. Ctek will be connected this w/e. I’m just shocked how quickly the battery loses charge. Must check out jev911’s suggestions as there are far fewer electrical components on the 993 than my Alfa 159 which copes fine with being left.
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mashby
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Joined: 12 Nov 2016
Posts: 74
Location: Coventry


PostPosted: Thu Dec 20, 2018 4:12 pm    Post subject: Reply with quote

The battery on mine was only lasting a week until I discovered the OBC display was staying lit. Now I've fixed it it lasts about 2 weeks or so.
Be careful thinking taking the frunk light bulb out will mean you can leave the bonnet ajar. The interior llights at least on mine appear to be on the same circuit and will stay on. Easier to clip the latch closed with a screwdriver or something.
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Albionmuz
Montreal


Joined: 28 Oct 2016
Posts: 594
Location: West Sussex


PostPosted: Thu Dec 20, 2018 4:23 pm    Post subject: Reply with quote

Thanks all, good to know I am not alone with this annoying foible!
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Will Statt
Nürburgring


Joined: 28 Aug 2003
Posts: 495
Location: Derbyshire


PostPosted: Thu Dec 20, 2018 5:15 pm    Post subject: Reply with quote

Mine runs flat after about 3 weeks.... or at least too flat to start. I now just disconnect the battery which take 2 mins.

Also.... when I do use my trickle charger, I find the bonnet seal is soft enough the let the thin charger wires be 'squashed' into it.... so I can still close the lid, so no need to remove bulb.

Old cars eh? Don't yah love 'em!
 
  
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Endoman
Barcelona


Joined: 11 Apr 2011
Posts: 1395
Location: Bolton U.K.


PostPosted: Thu Dec 20, 2018 5:28 pm    Post subject: Reply with quote

I use the Ctek with CTEK M6 Comfort Indicator Eyelet. If you push the bonnet locking catch down there is no need to remove the frunk bulb. Of course this relies on your car being garaged. If you disconnect the battery remember to go through the ecu self learning proceedure at startup.
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ToreB
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Joined: 13 May 2010
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PostPosted: Thu Dec 20, 2018 8:54 pm    Post subject: Reply with quote

I always recommend to disconnect the battery from the car if a charger is connected. I've see far too many overvoltage damages in the control units in these cars. The OBC tachometer is especially vulnerable to this, the internal overvoltage circuit can fail spectaculary. Non-OBC tachos does not have this.
Cheers,
Tore
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tyinsky
Hockenheim


Joined: 29 Jun 2012
Posts: 704
Location: London, UK

1997 Porsche 993 Carrera 2S

PostPosted: Thu Dec 20, 2018 11:31 pm    Post subject: Reply with quote

My battery sounds similar to the above. I've not counted the days out but in my head it is two weeks - maybe a bit more, could even be a but less. I have a battery switch connected and as long as I turn it off when I leave the car I never have any issues other than resetting the clock when I next use it.
 
  
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Albionmuz
Montreal


Joined: 28 Oct 2016
Posts: 594
Location: West Sussex


PostPosted: Fri Dec 21, 2018 7:46 am    Post subject: Reply with quote

ToreB wrote:
I always recommend to disconnect the battery from the car if a charger is connected. I've see far too many overvoltage damages in the control units in these cars. The OBC tachometer is especially vulnerable to this, the internal overvoltage circuit can fail spectaculary. Non-OBC tachos does not have this.
Cheers,
Tore


Great something else to worry about, although I don’t have an OBC. I do have a tracker though so disconnecting the battery is not an option..I don’t think?
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gunner
Hockenheim


Joined: 04 Jul 2014
Posts: 741
Location: Kent


PostPosted: Fri Dec 21, 2018 9:51 am    Post subject: Reply with quote

ToreB wrote:
I always recommend to disconnect the battery from the car if a charger is connected. I've see far too many overvoltage damages in the control units in these cars. The OBC tachometer is especially vulnerable to this, the internal overvoltage circuit can fail spectaculary. Non-OBC tachos does not have this.
Cheers,
Tore


I hadn't realised this was an issue either. I do have an isolator fitted though so would be easy to do when I plug the charger in.
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MJA911
Sepang


Joined: 10 Dec 2013
Posts: 2823
Location: Berkshire

2012 Porsche 991 Carrera

PostPosted: Fri Dec 21, 2018 10:09 am    Post subject: Reply with quote

Modern 911s not much different in my experience, 2-3 weeks not used and my 997s were hard to crank, if at all in the case of the GT3 which had a Porsche battery. CTEK trickle always now, even on the 991 which supposedly has a higher capacity battery for stop/start, but a battery with a Porsche badge on it is hard to trust.
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ragpicker
Reims


Joined: 14 Apr 2013
Posts: 4020
Location: North East England


PostPosted: Fri Dec 21, 2018 10:24 am    Post subject: Reply with quote

Same on both my 9*6's. Much more drain on the battery if the car is locked than if left open too.

Daughter's Renault Clio, been sitting there for 6 months whilst away. Fired right up on the first turn of the key yesterday - can you believe it!?
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ToreB
Approved Trader


Joined: 13 May 2010
Posts: 593
Location: Oslo, Norway


PostPosted: Fri Dec 21, 2018 11:15 am    Post subject: Reply with quote

Gents, it might be time for changing your batteries?
Normal current draw in a Porsche 964 or 993 with ignition off is about 25mA. (0.025A) An aftermarket alarm or other equipment can introduce an additional 5-50mA.
Theoretically, a fresh 75Ah battery would keep a 25mA current alive for about 100 days. Taking into account the needed power for cranking the engine, self-discharge and battery age, one could expect the battery to support at least a month of standing still and locked.
This is also my experience, my 993 starts fine after three-four weeks of storage. However, this of course require that the battery is fully charged when parking.
Cheers,
Tore
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Prattie
Trainee


Joined: 01 Aug 2014
Posts: 68



PostPosted: Mon Dec 31, 2018 12:07 pm    Post subject: Battery Drain Reply with quote

Been away for a long time so good to be back reading the threads.

Have always disconnected the battery when leaving car for a while. I have no electricity where its stored so purchased a solar panel , placed on the garage roof wires run to car.
Then a battery cut out switch on the neg earth side. Clip solar wires to the battery side of the cut out switch (not the wires to the car) that way the battery is receiving the charge and there is drain out.
This has no ongoing costs and seems to keep the battery up on charge OK. Once cut out fitted it stays there all the time just screw turn the cut out to reconnect when Solar wires disconnected.
Solar panels are available at Halfords large were about 40.00. Lots of people use them on campers etc. Cut outs cost 5.00/7.00 and can be fused.

Steve
 
  
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Prattie
Trainee


Joined: 01 Aug 2014
Posts: 68



PostPosted: Mon Dec 31, 2018 12:09 pm    Post subject: Battrrey Drain Reply with quote

Sorry should read "NO drain out".

Steve
 
  
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Pretzel
Hockenheim


Joined: 20 Apr 2014
Posts: 699
Location: Bedfordshire


PostPosted: Mon Dec 31, 2018 4:00 pm    Post subject: Re: Battery Drain Reply with quote

Prattie wrote:
Been away for a long time so good to be back reading the threads.

Have always disconnected the battery when leaving car for a while. I have no electricity where its stored so purchased a solar panel , placed on the garage roof wires run to car.
Then a battery cut out switch on the neg earth side. Clip solar wires to the battery side of the cut out switch (not the wires to the car) that way the battery is receiving the charge and there is drain out.
This has no ongoing costs and seems to keep the battery up on charge OK. Once cut out fitted it stays there all the time just screw turn the cut out to reconnect when Solar wires disconnected.
Solar panels are available at Halfords large were about 40.00. Lots of people use them on campers etc. Cut outs cost 5.00/7.00 and can be fused.

Steve


Do you have any problems with the alarm going off?
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