lofi Posted February 20 Report Share Posted February 20 Hi All, this might be two separate problems, but here goes. Boxster 981 been on the trickle charger over the winter and haven't used it for about three months. On a run out the other day I noticed that the incarnation voltage read out was sitting at 14.9v, which is way higher than I remember. Stayed that way over two 40 minute drives. Battery was tested and deemed ok. So I thought I would leave the car off the trickle charger. Checked a couple of days later and car was completely dead, couldn't unlock it open frunk etc. Anyway, got to the battery and it is at 4v. So I replaced it. Checked the next day and it was on 10v (ish, can't quite remember). So disconnected battery and put it on trickle and got it back to 12.6v. Next stage I wired an amp meter in series and watched the amp draw as the car when to sleep. Amp draw dropped to about 0.15A, then at stage 2 sleep 0.09A. That is not enough in my view to flatten a battery. I did start pulling fuses and with the horn siren fuse out the sleep draw goes down further to 0.02A, but as I said 0.09A is nothing so I cannot understand when the battery is draining. Which brings me back around to the alternator (which I suspect has a voltage regulator on it). Is it possible this is all related? Am I chasing two different issues? What is going on? Would welcome any advice before I start throwing a new alternator on and then potentially disappearing further down the the route of trying to find what could be a highly intermittent current draw (although the battery voltage drop off, plotted over 12 hours is a consistent downward line). Quote Link to comment Share on other sites More sharing options...
Nobbie Posted February 20 Report Share Posted February 20 If you are measuring all the current the battery is using then it won’t be draining the battery with 150mA. Might be worth taking the battery out, charging it up on the bench, disconnect it and then see if it then self discharges over a couple of days. Maybe the new battery is faulty? At least useful to eliminate this possibility first before changing anything else out. Quote Link to comment Share on other sites More sharing options...
lofi Posted February 20 Author Report Share Posted February 20 14 minutes ago, Nobbie said: If you are measuring all the current the battery is using then it won’t be draining the battery with 150mA. Might be worth taking the battery out, charging it up on the bench, disconnect it and then see if it then self discharges over a couple of days. Maybe the new battery is faulty? At least useful to eliminate this possibility first before changing anything else out. That's a good elimination idea, thanks. The battery arrived charged and was on 12.6v iirc, though I guess it could have been damaged in transit. Quote Link to comment Share on other sites More sharing options...
Paul P Posted February 20 Report Share Posted February 20 (edited) 14.9 volts is within spec for an agm battery. They have different charging characteristics and can take a higher charge especially in lower temps. They can go up to 15 and a bit. not being pedantic but when you say trickle charger do you mean a conditioner - they are different things and living on a trickle charger with a constant “input” won’t be good for the battery. sounds like the battery has simply died. Ideally the car needs to be told it’s got a new one of you replace it. It helps with the smart charging and the stop / start stuff. when you connect the trickle charger do you go direct to the battery or via the “chassis” negative connection. ? Edited February 20 by Paul P Quote Link to comment Share on other sites More sharing options...
lofi Posted February 20 Author Report Share Posted February 20 1 minute ago, Paul P said: 14.9 volts is within spec for an agm battery. They have different charging characteristics and can take a higher charge especially in lower temps. They can go up to 15 and a bit. not being pedantic but when you say trickle charger do you mean a conditioner - they are different things and living on a trickle charger with a constant “input” won’t be good for the battery. sounds like the battery has simply died. Ideally the car needs to be told it’s got a new one of you replace it. It helps with the smart charging and the stop / start stuff. Ok, maybe it isn't two different problems, but only one, and that 14.9/15v charging is ok (I just never remember seeing it that high). In terms of charger its a cTek conditioner thing. Do you mean the new battery has also died, i.e. your thought is that the voltage drop is a fault with the battery? Maybe - I'll try Nobbie's suggestion and disconnect it and see what happens. Quote Link to comment Share on other sites More sharing options...
Carmine Posted February 20 Report Share Posted February 20 You say you tested the original battery and it tested OK - can you expand on how that was done? What charger/maintainer are you using? Was the car stored indoors or outside? If outside can you confirm the drains aren’t blocked and that the carpets are completely dry? Quote Link to comment Share on other sites More sharing options...
lofi Posted February 20 Author Report Share Posted February 20 Just now, Carmine said: You say you tested the original battery and it tested OK - can you expand on how that was done? What charger/maintainer are you using? Was the car stored indoors or outside? If outside can you confirm the drains aren’t blocked and that the carpets are completely dry? It was tested at a well know specialist - I dont know what they did to be honest. It is a cTek Multi XS 3600 (quite old) Car is kept in the garage. Drains are clear, regularly rodded with my trumpet cleaner, drain valves removed, carpets dry last time I checked (not recently). Quote Link to comment Share on other sites More sharing options...
Carmine Posted February 20 Report Share Posted February 20 Not familiar with that particular Ctek charger; does it have an AGM mode? Quote Link to comment Share on other sites More sharing options...
iborguk Posted February 20 Report Share Posted February 20 1 minute ago, Carmine said: Not familiar with that particular Ctek charger; does it have an AGM mode? Yes https://www.ctek.com/storage/1A65B6CD49EBFD75CB311F65CFCB0BB3ABEE98B4061C7104DA41C131AFF108D2/8d6933fbed2d448dbf01bcb27a3564f8/pdf/media/8e24392296004fa3801aa7a6696a8430/MXS_3600-manual-low-UK-EN.pdf Quote Link to comment Share on other sites More sharing options...
lofi Posted February 20 Author Report Share Posted February 20 (edited) 2 minutes ago, Carmine said: Not familiar with that particular Ctek charger; does it have an AGM mode? it does not - it has 6v, 12v and frost, though I now see this is for AGM batteries. Seems I've had it on the wrong setting for four years! Edited February 20 by lofi Quote Link to comment Share on other sites More sharing options...
iborguk Posted February 20 Report Share Posted February 20 1 minute ago, lofi said: it does not - it has 6v, 12v and frost protection Check the manual link above. Frost mode also applies to AGM. Quote Link to comment Share on other sites More sharing options...
iborguk Posted February 20 Report Share Posted February 20 Detail on page 3. Quote Link to comment Share on other sites More sharing options...
lofi Posted February 20 Author Report Share Posted February 20 1 minute ago, iborguk said: Check the manual link above. Frost mode also applies to AGM. Thanks - I never knew that. Bit unclear whether that setting is always for AGM batteries or just if sub 5 degrees. Quote Link to comment Share on other sites More sharing options...
iborguk Posted February 20 Report Share Posted February 20 (edited) I read that as “applies to many AGM batteries” Thats the mode I’d be using with my AGM battery. Edited February 20 by iborguk Quote Link to comment Share on other sites More sharing options...
Paul P Posted February 20 Report Share Posted February 20 12 minutes ago, lofi said: Ok, maybe it isn't two different problems, but only one, and that 14.9/15v charging is ok (I just never remember seeing it that high). In terms of charger its a cTek conditioner thing. Do you mean the new battery has also died, i.e. your thought is that the voltage drop is a fault with the battery? Maybe - I'll try Nobbie's suggestion and disconnect it and see what happens. I guess the new battery could be faulty but i would be trying to “level the field” on the variables. when using the ctek it shouldn’t be direct to the battery. It should be battery positive and chassis negative. Ideally the car should have been told it had a new battery. Otherwise it will continue to charge the new one like it was charging the old one. It doesn’t appear to be a good vs bad thing. Many appear to have no apparent ill effects of not coding the battery and it’s unknown how far the “smarts” go with charging but if you are chasing potential charging issues then eliminating the doubt seems sensible. the test that @Nobbie suggests seems a solid way of eliminating the new battery as an issue. after that then perhaps a longer test of drain is needed. For earlier gen cars I think it’s upwards of an hour before the car goes into proper sleep and that’s with the door and boot latches tripped to make the car think it’s locked. Quote Link to comment Share on other sites More sharing options...
lofi Posted February 20 Author Report Share Posted February 20 3 minutes ago, Paul P said: I guess the new battery could be faulty but i would be trying to “level the field” on the variables. when using the ctek it shouldn’t be direct to the battery. It should be battery positive and chassis negative. Ideally the car should have been told it had a new battery. Otherwise it will continue to charge the new one like it was charging the old one. It doesn’t appear to be a good vs bad thing. Many appear to have no apparent ill effects of not coding the battery and it’s unknown how far the “smarts” go with charging but if you are chasing potential charging issues then eliminating the doubt seems sensible. the test that @Nobbie suggests seems a solid way of eliminating the new battery as an issue. after that then perhaps a longer test of drain is needed. For earlier gen cars I think it’s upwards of an hour before the car goes into proper sleep and that’s with the door and boot latches tripped to make the car think it’s locked. Thanks - that's all sensible. I do have the conditioner set up like that, battery positive and to the chassis negative. I will get a coder and do the battery, I understand the iCarSoft POR V2.0 and V3.0 can do this. Seems just a sensible precaution. I'll also do the @Nobbie test. When I did the drain test I didn't wait that long, but it did have the latches tripped, with the exception of the frunk, which I couldn't work out how to do. Quote Link to comment Share on other sites More sharing options...
iborguk Posted February 20 Report Share Posted February 20 6 minutes ago, lofi said: Thanks - that's all sensible. I do have the conditioner set up like that, battery positive and to the chassis negative. I will get a coder and do the battery, I understand the iCarSoft POR V2.0 and V3.0 can do this. Seems just a sensible precaution. I'll also do the @Nobbie test. When I did the drain test I didn't wait that long, but it did have the latches tripped, with the exception of the frunk, which I couldn't work out how to do. In case it’s of use Quote Link to comment Share on other sites More sharing options...
Carmine Posted February 20 Report Share Posted February 20 Consider getting a battery tester such as this one - https://amzn.eu/d/fAlDGjS allows you to see battery health for yourself. Quote Link to comment Share on other sites More sharing options...
iborguk Posted February 20 Report Share Posted February 20 (edited) I have this one , does the job including cranking , charging and load tests. https://amzn.eu/d/fuQAMtx Edited February 20 by iborguk Quote Link to comment Share on other sites More sharing options...
lofi Posted February 20 Author Report Share Posted February 20 I have a bluetooth monitor on the battery currently (it is not on there all the time) which is recording the voltage and can do a charging and voltage test. Not sure how good it is amazon battery monitor BM2 Quote Link to comment Share on other sites More sharing options...
Carmine Posted February 20 Report Share Posted February 20 It’s fine for basic voltage info but doesn’t really tell you much about the battery health. Typically those testers linked above take into account the battery size and type and then report back the battery’s state of health and state of charge. Much more informative and meaningful. Quote Link to comment Share on other sites More sharing options...
lofi Posted February 21 Author Report Share Posted February 21 Right, battery fully charged over night. Will now disconnect from car and see what it does, just to rule that out. Quote Link to comment Share on other sites More sharing options...
ATM Posted February 21 Report Share Posted February 21 I left my 981 for 2 months maybe over winter and just drove it today for the first time. Battery was dead and showing 4v on my charger. I charged it for 24 hours and out it in the car and the car started fine. I will now see if it holds charge. I have a booster pack on hand if it fails to start. My car was showing 15.0v once I started it so that is as explained normal for these cars. Regarding the alternator. I believe these modern cars have complicated electrical systems. Not sure why I think this but thats my belief. So these alternators do not charge constantly like older cars. This is for emissions as an alternator constantly blasting out peak amps will cause a drag on the engine and increase emissions. Not sure if that helps explain whats going on with your car. Quote Link to comment Share on other sites More sharing options...
lofi Posted February 21 Author Report Share Posted February 21 48 minutes ago, ATM said: I left my 981 for 2 months maybe over winter and just drove it today for the first time. Battery was dead and showing 4v on my charger. I charged it for 24 hours and out it in the car and the car started fine. I will now see if it holds charge. I have a booster pack on hand if it fails to start. My car was showing 15.0v once I started it so that is as explained normal for these cars. Regarding the alternator. I believe these modern cars have complicated electrical systems. Not sure why I think this but thats my belief. So these alternators do not charge constantly like older cars. This is for emissions as an alternator constantly blasting out peak amps will cause a drag on the engine and increase emissions. Not sure if that helps explain whats going on with your car. Thanks @ATM that is helpful because it likely explains the 15v I have been seeing, which I think means the alternator is a non-issue. Subject to the battery not discharging itself over night (out of the car) proving its ok, I think I'll be back to chasing down current draw. One thing that has peaked my attention is that the driver's side window one touch function will not work and will not relearn. I wonder if the door control module could have developed a fault. Quote Link to comment Share on other sites More sharing options...
ATM Posted February 21 Report Share Posted February 21 Just now, lofi said: Thanks @ATM that is helpful because it likely explains the 15v I have been seeing, which I think means the alternator is a non-issue. Subject to the battery not discharging itself over night (out of the car) proving its ok, I think I'll be back to chasing down current draw. One thing that has peaked my attention is that the driver's side window one touch function will not work and will not relearn. I wonder if the door control module could have developed a fault. I think there is a procedure for resetting this. When you say relearn have you followed this procedure? Quote Link to comment Share on other sites More sharing options...
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