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992 Turbo S flat lithium battery. What to do if this happens to you...

RobG992TS

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Hello all,

Popped out to the garage because it has been a while since I last used my car and I thought it would be sensible to attach the Ctek trickle charger I'd bought in preparation for the ~6 month storage it'll have over the winter. I last used it in October on the way back from a long weekend in France, so the last journey was a good few hours long...

Walked up to the car and it didn't open the doors by proximity. Fair enough, it often doesn't work if it's been idle for more than a few days at a time and I know this feature times out with lack of use. I pressed the open button on the remote and, nothing. Not a beep, click, or light anywhere. The lithium battery is dead and I'm staring down the barrels of a very costly replacement because I've not had it connected to a trickle charger for 10 weeks. Bugger!
Whether the battery was dead or not, I still needed to get to it so it could be checked and/or removed, so here's a little guide that you might all be aware of already but could be useful for some:

In the key fob there is a small blade that you have to slide out with your fingernail. This blade fits into a secret, hidden lock, that is under the driver's door handle. You do need to fully lift the handle in order to clear it and hold it open fully while inserting and turning the blade to avoid scratches. The blade only works one way up (although apparently fits in in both orientations), and only in one direction.
Once turned 90-degrees to unlock, the blade can be removed and you can then re-pull the handle to gain access to inside the car. The next thing you need to do is reach over to the passenger side and open the plastic cover that houses the relays in the passenger footwell. There is no way that I could get the passenger door open, so leaning over the centre console was the only way for me. Care must be taken to not lean on the passenger seat with your hand or you may break the heating mat and/or proximity sensor in the seat base that indicates a passenger is present.
With the cover of the fuse box removed, you will see a red/orange 'plug' in the centre. This must be pulled out until it stops and has a copper piece on the side of it. That's the positive jumper that you then need to attach either another 12v battery to, or in my case my trusty Noco booster.
The negative can be attached to the opened door latch or hinge to make the circuit.
With power now applied, the bonnet release can be operated next to the driver's seat and the bonnet will unlatch. Yippee!!

The next stage iss to attach the Noco directly to the battery positive and the negative post by the windscreen wiper mechanism. I then powered on the Noco and left it supplying power for 5 minutes. This, I'm told, gives the battery enough juice to bring it out of dormant mode. After 5 minutes, I disconnected the Noco and hooked up the dedicated lithium Ctek that I should have connected 10 weeks ago. Bingo, battery charging.

I've had the Ctek connected for 24hrs now and can safely say that all is well. The car started in the garage and ran happily for the couple of minutes I allowed it to before shutting off and reconnecting the Ctek again for the months ahead.

Just a little helping hand for anyone who may worry they need to replace the horrendously expensive lithium battery now or in the Spring!
Merry Christmas.
 
They are a bit of a nightmare if allowed to go flat completely. Had it happen once whilst waiting at the ferry terminal. Porsche Assist were brilliant but was the last car on the boat - squeaky b*m time.
Useful tip for everyone - thanks.
 
The manual suggests using the key fob release rather than the one in the cabin (driver's door kickplate switch) as very often, there is insufficient power to overcome resistance in the car's electrical circuits. 👍🏼

Regards,

Clive
 
Things we forget #99

On the 981 platform, holding the key fob against the offside windscreen pillar helped activate locks if fob battery was low. I guess the receiver was in that location.
 
I have experienced this on my previous 992 GT3 and by chance found the solution documented in the CTEK User Manual.
One of the "features" of the Lithium Batteries fitted to 992 GT3, Turbo S etc. is they have a protection circuit within the battery which will activate under certain conditions (see below) and internally disconnect the terminals thereby removing all power to the car and since the CTEK Lithium XS Charger needs to detect voltage on the battery terminals it cannot charge the car in this condition as there is no voltage. Using a 12V Booster on a Lithium Battery is not recommended, it can at best cause long term damage to the battery at worst cause a thermal runaway leading to a fire.

The best solution is within the CTEK Lithium XS Charger and it's really simple.
Having got into the car and opened the bonnet, as RobG992TS has described, all you need to do is attach the CTEK to the battery terminals and hold the reset button for 10 seconds. This will cause the CTEK to apply a 12V pulse to the battery which will override the protection circuit and reconnect the battery terminals internally in the battery, during this process Stage 7 on the CTEK is lit and from this point on the CTEK will detect voltage and begin to charge the battery.
The conditions under which the Lithium Battery Protection Circuit activates are:
1. When state of charge drops below 15%
2. When battery voltage drops below 10V
3. If the battery voltage goes below 6.5V or above 18V the circuit opens permanently and cannot be reset
4. The circuit also opens if the battery overheats or there is a short circuit.

Conditions 1 and 2 are recoverable
Condition 3 means a new battery is required
Condition 4 - A short circuit or overheating may cause significant damage to the battery that results in the battery can no longer be recovered or it may still be recoverable but it's life reduced.

The above solution works if your car is in your garage and you happen to have your CTEK Lithium XS nearby and the means to get into the car and open the bonnet. Inevitably it can also happen the next morning after an overnight hotel stay then it becomes a problem resulting in a Porsche Assistance Call Out. Having had the experience with my GT3 at home in the garage and not wanting to go through that again with it or now, my Turbo S, I decided to buy some kit to be able to deal with the problem away from home. My solution was to purchase a 12V power bank, make up a long set of leads with croc clips so I could get 12V into the terminal in the passenger footwell fusebox and buy a CTEK CS Free Cordless Charger (it is compatible with both AGM and Lithium batteries) which unlike the Lithium XS does not have the ability to send a 12V pulse to reset the battery protection circuit, however, the 12V Power Bank as well as supplying the 12V required to get the bonnet to open can be used to reset the battery (a Nocco Booster could be used to get the bonnet open but not recommended to open the protection circuit on a Lithium battery.) The CTEK CS Free will hold its full charge for 12 months and with its adaptive charging there is enough capacity to get the battery sufficiently charged to enable the car to be started.
 
Wow!! Good reminder! I was in hospital for about 6 weeks a couple of weeks back (all good now and no side effects) Anyway I came home to a flat battery on my 991.1 4S. It had enough juce to unlock the doors but not enough to open the bonet. I called the AA out and they did the fix described by Rob.
However,.....I took delivery of a 992.2 4 GTS just before Christmas and its been sitting on the drive with 4" of snow on it for about a week. Wasn't planning on taking it out in this weather, but this post has just prompted be to get into it and start it (hopefully) to get the battery charged up. Only thing I dont know is how the 400V battery interfaces or transforms down to 12V. I just dont know if I have a 12V battery AND a 400V battery or if the 400V battery drops down to 12V via a step down transformer. So if I do have a flat battery, I dont know yet, where I wild connect the 12V.
Does anyone know?
Ta, Bruce
 
You have 2 batteries. The large battery one tops up the small if it becomes depleted, but it is hidden and I don't believe there is any easy way to charge it at home as a DIYer.
Regards,

Clive
 
Ta for that Clive, I'll try to dig around and see what else I can find on it. Yeah its confusing me a wee bit ("wee" - Scottish expression for "small")
I understand what a tricle charger is and what it does, same for jump starting but in the GTS case I'm confused. I would imagine that if you had a triccle charger which would of course need to be connected to the 12V service battery but is it that when the 12V is fully charged it starts to charge the 400V battery or is the 400V batter not a 400V battery at all and just a big 12V battery that steps up to 400V for the Hybrid stuff? I dont even think I have a starter motor. A lot for me to reserch and all part of the fun of ownership.
Thanks again
Bruce
 
Hi Bruce,
No starter, 2 batteries and no access to either of them.
Perhaps have a word with your PC service manager to obtain the lowdown on how it's all set up.
We got a brief outline of the system when we visited Reading PC on a 992 Register outing recently.

Regards,

Clive
 
Out of interest, im in 992.1, how long is it generally ok to leave them before worrying about the battery.

Same as Bruce, im up in Scotland, Aberdeen and covered in snow
 
Porsche say around 6 weeks, but it is dependant upon the condition and age of your battery. Personally, I would connect a CTEK up if I were leaving my vehicle for any more than 2-3 weeks.

Regards,

Clive
 
Having had the experience with my GT3 at home in the garage and not wanting to go through that again with it or now, my Turbo S, I decided to buy some kit to be able to deal with the problem away from home. My solution was to purchase a 12V power bank, make up a long set of leads with croc clips so I could get 12V into the terminal in the passenger footwell fusebox and buy a CTEK CS Free Cordless Charger (it is compatible with both AGM and Lithium batteries) which unlike the Lithium XS does not have the ability to send a 12V pulse to reset the battery protection circuit, however, the 12V Power Bank as well as supplying the 12V required to get the bonnet to open can be used to reset the battery (a Nocco Booster could be used to get the bonnet open but not recommended to open the protection circuit on a Lithium battery.)

Ctek are currently looking into producing their CS Free Cordless Charger with an added 12v pulse button for use in resetting battery protection circuit. Consequently, if you're in no hurry to purchase one right way, it may pay to hang fire for a while and see if this becomes available.

Regards,

Clive
 

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