718 Dead Battery - CTEK MXS 7.0 Supply - Page 2 - Boxster/Cayman - PistonHeads UK

N1KKX said: I left my 2001 718 for 2 months in the garage in Italy. Upon returning last week the battery was completely dead. I used the manual key to get into the cockpit. Tried to open the front bonnet but nothing at all. Pulled the positive tag from the fuse box in the footwell and connected a power bank to this and the door latch. Nothing. Left it for a few minutes, still nothing. Changed the power bank for a new fully charged battery and connected this in the same way with jump leads. Left it for 30 mins and tried again...nothing. Purchased the CTEK MX 5.0 charger and the cigarette lighter socket adaptor and plugged this into the socket in the passenger footwell. Mains light comes up green but no orange lights indicating charge is working. After a couple of minutes green light goes out. It seems that this is because the charger doesnt detect a battery and probably this is because the battery voltage has dropped below 2v. the threshold for this charger. I now have the MXS 7.0 arriving tomorrow that has the 'Supply Program' option that will work regardless of battery voltage and I plan to try that. My question is if anyone has had a similar experience and if I am missng something...I am surprised that after only 2 months the battery voltage is apparantly below 2v. I have read some posts that suggests that the doors need to be open, or closed, or locked, otherwise the system shuts down and you cant charge through the 12v socket? Does anyone have any more information on this? I hope someone can help otherwise I will have to bite the bullet and remove the left front wheel and inner wing trim and find the manual pull, or call the local POC! Could be the original 22 year old battery is just dead. Hang on a minute... 2001... 718...???

Oops! 2021…

I left my 2021 718 for 2 months in the garage in Italy. Upon returning last week the battery was completely dead. I used the manual key to get into the cockpit. Tried to open the front bonnet but nothing at all. Pulled the positive tag from the fuse box in the footwell and connected a power bank to this and the door latch. Nothing. Left it for a few minutes, still nothing. Changed the power bank for a new fully charged battery and connected this in the same way with jump leads. Left it for 30 mins and tried again...nothing. Purchased the CTEK MX 5.0 charger and the cigarette lighter socket adaptor and plugged this into the socket in the passenger footwell. Mains light comes up green but no orange lights indicating charge is working. After a couple of minutes green light goes out. It seems that this is because the charger doesnt detect a battery and probably this is because the battery voltage has dropped below 2v. the threshold for this charger. I now have the MXS 7.0 arriving tomorrow that has the 'Supply Program' option that will work regardless of battery voltage and I plan to try that. My question is if anyone has had a similar experience and if I am missng something...I am surprised that after only 2 months the battery voltage is apparantly below 2v. I have read some posts that suggests that the doors need to be open, or closed, or locked, otherwise the system shuts down and you cant charge through the 12v socket? Does anyone have any more information on this? I hope someone can help otherwise I will have to bite the bullet and remove the left front wheel and inner wing trim and find the manual pull, or call the local POC! Edited by N1KKX on Monday 15th January 18:21

The system shuts down the 12v socket 30 minutes after Ignition Off. So to charge via that method just connect and start charging before that happens. The 12v socket will then stay live indefinitely. However, if you can't get the ignition to turn on then obviously that won't work. If your battery really has dropped to 2v then it is dead, I would not attempt to charge it in the car. If it really is 2v and you want to try raising the dead... remove it from the car and charge it somewhere safe. Edited by M11rph on Monday 15th January 18:41

Thanks. I was planning to just get enough charge into it this way to pop the bonnet and then charge normally. Thanks for the info.

Isn’t there an emergency access wire inside the front wheel arch behind the inner liner still? It sounds like no amount of charge is going to ignite that battery but I’m surprised a positive charge to the fuse box connector didn’t work.

That’s my next step but of course the locking wheel nut socket is in the front boot. I believe it’s an ABC59 type socket I’m going to need to get the wheel off, and a jack that goes low enough to get under the car. I’m surprised by the low 2v battery level after only 2 months and the power to the fuse box positive not working which is why I wondered if there’s some form of ‘lock out’ at work here.

Yep. There is a release cable behind the left side wheel arch lining however you will need to take the wheel off to take the liner out howevever, you may be able to take it out if you jack the car up but it will be a PITA. The first thing I did when I got my 718 was take the locking wheel nut out of the frunk and put it in the glove box. I agree with others, the battery is most probably dead as a dodo but the question is what has drained the battery over a 2 month period? This would be my first concern. Replace the battery with a new one and take it from there.

Also in future connect the CTEK directly to the battery + terminal and the strut top earth. No issues then with any 12v socket shutting down.

Everybody talks about the sockets going dead after 30mins but on my 718 GT4, plugging into either outlet (passenger footwell or centre console) and it stays charging. Dive left it for a few weeks before and then unlocked and plugged it in this way without touching the ignition and it worked. OP - are you sure that you are getting a good earth when going via the fuse box? That would be my first thought? Secondly I’m sure I’ve read before that once connected people had to leave for ~15mins like this before it would open.

https://www.youtube.com/watch?app=desktop&v=lv...

Is the 2v minimum really so. I have the same charger and used it successfully on my wife’s Focus battery which was showing 1.4V on a multi-meter. Initially I tried using a CTek extension lead but this failed to deliver anything to the battery. I took the extension lead out of the equation and then left it on “recondition” mode overnight and all is good now. This was just last week.

I agree I am suspicious about the 2v as well. I only say this is the state of charge as this is apparently the voltage below which the MX5 charger believes there is no battery attached. When you charged your wife’s car did any of the amber charge lights come on? I also wonder about the earth connection. I’ve tried many times and ‘wiggled’ it about a number of times. I’m going to give it one last go tonight with the new donor battery and jump leads as well as try the MXS7 through the passenger 12v socket. If this doesn’t work then I’m just going to call the Porsche guys out. As a final thought the ignition key is currently stuck in the ignition in the off position. I will also try to remove this tonight by popping the cover off and using the ‘pick’ that is apparently also in the fuse box. I now wonder if this is also having any effect? Thanks to everyone for the helpful comments.

Thanks to AmoCS for the video link. That’s convinced me that I won’t be bothering with that! Too much bending and faffing around to get that splash guard off at my age! If the charger doesn’t work tonight then it’s off to the Porsche Centre in Firenze!

Have a look here - https://www.718forum.com/threads/tool-on-inside-of... Does sound like the key being in there might be locking out the system from enabling you to enter it. Out of curiosity, how did the key get in there in the first place? Could the ignition have been on which drained the battery?

Tony B2 said: Is the 2v minimum really so. I have the same charger and used it successfully on my wife’s Focus battery which was showing 1.4V on a multi-meter. Initially I tried using a CTek extension lead but this failed to deliver anything to the battery. I took the extension lead out of the equation and then left it on “recondition” mode overnight and all is good now. This was just last week. Interesting comment. My cars have been put away and on CTEKs for a couple of months as we are away in Spain. My Macan kept reaching level 5 on the CTEK then the dreaded red light came on which indicates a battery problem. I just happened to take out the CTEK extension lead and connect the charger directly to the battery eyelet connector and it's gone through the whole cycle and seems to be holding at level 7 after a week from what I can see from my CCTV camera. I do wonder if sometimes the CTEK extension lead causes issues?

OK . Listen up . I had exactly the same problem as you last week . Left my GT4RS locked up in garage and forgot to put it on the CTek MX5 charger for about 7 weeks since last starting it. There was just enough battery to open the car but otherwise it was dead. I inserted the key, but then couldn't remove it. I tried plugging the Ctek into both the cigar lighter and footwell sockets but after a minute the charger light flashed indicating battery not found. You need to connect the Ctek direct to the battery because it is so flat. So you have to open the front hood. I got a battery out of my Golf and connected to the pull-out +ve terminal in the drivers side footwell fusebox and earth to the door checkstrap. Flick the bonnet switch and your in. Connect the charger crocodile clips, red to the +ve battery post and -ve to the windscreen motor earth post and leave on charge for at least 24 hours. I'll be topping up the charge regularly in future via the footwell socket.

JurassicGTS said: Tony B2 said: Is the 2v minimum really so. I have the same charger and used it successfully on my wife’s Focus battery which was showing 1.4V on a multi-meter. Initially I tried using a CTek extension lead but this failed to deliver anything to the battery. I took the extension lead out of the equation and then left it on “recondition” mode overnight and all is good now. This was just last week. Interesting comment. My cars have been put away and on CTEKs for a couple of months as we are away in Spain. My Macan kept reaching level 5 on the CTEK then the dreaded red light came on which indicates a battery problem. I just happened to take out the CTEK extension lead and connect the charger directly to the battery eyelet connector and it's gone through the whole cycle and seems to be holding at level 7 after a week from what I can see from my CCTV camera. I do wonder if sometimes the CTEK extension lead causes issues? I think the extension leads are a bit carp, in fact. I had to return one which never worked and the one I have now seems very inconsistent.

I will try again without the extension lead as it seems to be a common complaint. Thanks for the input.

N1KKX said: I agree I am suspicious about the 2v as well. I only say this is the state of charge as this is apparently the voltage below which the MX5 charger believes there is no battery attached. When you charged your wife’s car did any of the amber charge lights come on? I also wonder about the earth connection. I’ve tried many times and ‘wiggled’ it about a number of times. I’m going to give it one last go tonight with the new donor battery and jump leads as well as try the MXS7 through the passenger 12v socket. If this doesn’t work then I’m just going to call the Porsche guys out. As a final thought the ignition key is currently stuck in the ignition in the off position. I will also try to remove this tonight by popping the cover off and using the ‘pick’ that is apparently also in the fuse box. I now wonder if this is also having any effect? Thanks to everyone for the helpful comments. When attempting to charge with the extension lead in place, the charger initially showed the first ("Try") LED flashing, but after a while (not sure how long because I did not keep watching it, in the freezing cold outside) this extinguished and subsequently the "!" LED came on (can't remember whether it was flashing, or continuous). This happened regardless of charging mode. Without the extension lead - which I have used successfully whilst charging my Spyder - it charged with no problem, and the battery has been fine since, in spite of the cold weather and numerous short runs. I reckon the extension lead connectors are to blame, and possibly when cold, the plastic shrinks slightly, there is a less reliable connection between the metal parts, causing increased resistance (?) and the charger, being "smart" interprets this as a problem, and gives up trying.

Thanks. I’ll avoid using the extension lead.

Update. So I eventually got the bonnet up with the help of the roadside mechanic guy who did the usual thing with the positive tab in the fuse box etc. It looks like I just wasn’t ‘aggressive’ enough making sure the negative connection was well made on the door hinge strap. Got it jumped started with no problems and have now left it on the trickle charger. But, the trickle charger indicator lights show that it’s almost fully charged so I am still anticipating problems. If it’s really that charged already then why all of the drama to get the bonnet to unlock? I’ll leave it charging for a day and then see how it goes when I take the charger off.

It's good that you've made progress anyway! It would have been interesting to know the battery voltage before it was jump started with a direct measurement off of the battery. Whilst you are having these issues it might be handy to put the Battery Voltage on the MFD (the small right hand dispaly in the instrument binacle) if you haven't already done so. There are 4 lines for information and you can select what you want displayed. It will show you the resting voltage when you turn the ignition ON and the charging voltage when the engine is running. If it's been on the trickle charger then that won't be as useful, battery state/ resting voltage is best measured after 24 hours without any input, but might prove to be of interest. These cars do have quite a high consumption even when shut down. Interior alarm monitoring and tracker system might be to blame? Mine showed 11.9V after about 3 weeks of no use, which is approximately 30-40% capacity remaining.

I regularly leave the car for a week or more in the garage so I will switch the display to that in future so I can monitor it. Good to know, thanks. I really must read the manual one day!

Also depending on your propensity for buying Chinese tat from Amazon, you could get a multi-meter. It's what I get out first when I have any electrical problems so I can see voltages and also check for connectivity. ETA obviously there are a range of qualities of multi-meters available. Edited by BertBert on Thursday 18th January 14:39

N1KKX said: But, the trickle charger indicator lights show that it’s almost fully charged so I am still anticipating problems. Mine started doing that recently. I have a monitor on the battery so can see what's happening. I turn the charger off for a few seconds and on again and it works as it should.

Having now opened the bonnet I’ve put the battery on charge. Initially seemed fine but after 24 hours the red light came up so we stopped the charge. Battery showing as 75% full. Tried to start the car but no response at all. Jumped it from a new battery and it started fine. Ran it for 30 mins. Info on screen says charging at 14.3v. After 30 mins turned off and tried to start again but again nothing. Jumped it again, this time from a power pack, and again started fine. Now charging on another charger, C-Tek MSX5.0 which immediately put it into recon mode. Planning to leave it overnight and see how it gets on. Expecting to have to take it to OPC tomorrow. I’m just interested in any info as to how the battery can apparently be well charged but nothing happens and yet it jump starts straight away from two other sources? I guess it’s just the battery is ‘shot’? It’s only just over 3 years old. Doesn’t seem reasonable? Interested in the views of those who obviously know more than me on this subject.

BertBert said: Also depending on your propensity for buying Chinese tat from Amazon, you could get a multi-meter. It's what I get out first when I have any electrical problems so I can see voltages and also check for connectivity. ETA obviously there are a range of qualities of multi-meters available. Edited by BertBert on Thursday 18th January 14:39 Can anyone suggest a good quality meter on Amazon I can get. I see they go from £20 to £400!

It's simply a case that your existing battery does not have the 'guts' to start the car, when connecting it to an alternative battery you are drawing the required current from that battery. Any meter on Amazon will be fine if all you are wanting is to measure voltage, example here £8.49: http://tinyurl.com/3f862byn

N1KKX said: Having now opened the bonnet I’ve put the battery on charge. Initially seemed fine but after 24 hours the red light came up so we stopped the charge. Battery showing as 75% full. How are you measuring the charge state of the battery? via multimeter or something else? Are you measuring this a few minutes after disconnecting from charge? The voltage will naturally drop back once off charge towards 12.7v I'd strongly bet the battery wasn't 75% if you couldn't start the car without using a jump pack. This would or should be around 12.4v If you've taken the battery down below 11v it may require a few charging cycles to get enough base charge in before it'll charge properly and you may well have done permanent damage. Are you using AGM mode on the CTEK? Does the charger eventually get to stage 7?

N1KKX said: BertBert said: Also depending on your propensity for buying Chinese tat from Amazon, you could get a multi-meter. It's what I get out first when I have any electrical problems so I can see voltages and also check for connectivity. ETA obviously there are a range of qualities of multi-meters available. Edited by BertBert on Thursday 18th January 14:39 Can anyone suggest a good quality meter on Amazon I can get. I see they go from £20 to £400! \ Fluke is a good brand (101?) ... but I can't guarantee that it's not manufactured in China ....

Unless you are doing this day in day out dropping £300+ on fluke digital multimeter is massively OTT, let alone £5k for a battery analyser. Lovely bits of kit tho’ A £10 screwfix multimeter will be good enough for 99% of cases. Anything that’s accurate to +/-0.05v is going to do.

Just buy a new battery. The charger has not done its job and the battery is now gone. Still surprised the battery was sub 2v though, if it was. I would get a clamp meter and start pulling fuses, when the car is asleep, and see what is draining it so quickly. Is there a tracker fitted? Dash cam? Where you the first owner?

There's no mystery here. Batteries going flat with a parasitic drain are de-rigour in modern cars. My most recent modern car (Evora) wouldn't last 2 weeks in the garage not being on a conditioner. Once a lead acid battery has been fully discharged it's dead and will do exactly as the OP has seen. As has been said, just get a new one. Then work out how to keep it on a conditioner if it's going to be left for any amount of time. And I'm sure that someone has an example of a very deeply discharged battery that has come back to life, but the OP's is dead.

b0rk said: Unless you are doing this day in day out dropping £300+ on fluke digital multimeter is massively OTT, let alone £5k for a battery analyser. Lovely bits of kit tho’ A £10 screwfix multimeter will be good enough for 99% of cases. Anything that’s accurate to +/-0.05v is going to do. I agree that the price range is £50 to £5000 in the Fluke range ... but I have previously owned two from the usual inexpensive suspects that have failed when I needed them. Nothing ever goes wrong when you aren't using it !

Ed.Neumann said: Just buy a new battery. The charger has not done its job and the battery is now gone. Still surprised the battery was sub 2v though, if it was. I would get a clamp meter and start pulling fuses, when the car is asleep, and see what is draining it so quickly. Is there a tracker fitted? Dash cam? Where you the first owner? The BMS, immobiliser, factory fitted tracker, smart functions etc will all slowly drain the battery. 2 months is pretty good going really. New cars post manufacture are put in transport / storage modes to shut everything down these days. 2v is dead cells and internal resistance, once it’s dropped below 11v then it doesn’t take long at all to get down to 2v. 2v via the BMS or something connected to the BMS is just the system voltage via the reader being read back when the battery is electronically shut off. The battery could probably have been saved if connected to a good battery for a few hours then attached to a CTEK or similar charger until fully charged. 72hrs+ CTEK has charging and monitoring sub stages within each main stage to check that the battery is holding charge. Most good smart chargers do. However cycle the battery when discharged or with cells that are effectively discharged and it’s toast. Using a jump pack multiple times really does suggest the battery is capable of holding charge.

OK, old battery is coming out, new one going in and I’ll attach the flying leads to the battery and negative post so I can plug the C-Tec charger into the battery whenever I’m going to leave it for any more than a week. That’s my job for the weekend!