westcoastj

I'm having some battery issues, and not sure if this is related. I have a 2022 C2S (Li battery) so not covered by the TSB. However, lately I 've been having issues where the comfort access no longer works (handles don't come out automatically - I have to press the fob) and even when the door handles pop up after using the fob, I can't actually open the doors (I get error message "To open, let go of door handle and pull again"). I'm now getting a message on my PCM saying that my 12v battery is low and to connect it to charging equipment, however, when I connect it to my Porsche Charge-o-matic, it says the battery is full? When the car is running, battery is showing good as well. I have a dashcam hardwired, but parking mode is not activated, so that it turns off when I turn off the car, so should not be draining the battery. Any thoughts what the issue might be?

leloupgris

Very strange issue indeed! Where are you plugging your charger? Directly on the battery terminals or you're using the negative post on the side?

Two days ago on the 992 I had the same issue with the door handles message "to open, let go of door handle and pull again" when the battery discharged and I had to jump start it. When I exited the car and closed the door (not locked it, simply closed it), I could not open it again, even though I had the charger plugged to the battery and the car was supposedly unlocked. The same message was displayed on the dashboard. Letting go of the handle and pulling it again had no effect, both on driver's and passenger's side. Pressing the key fob to unlock it would see it cycle through locking and unlocking the doors, but I was still not able to open it. Same with pressing the lock button and then the unlock button. I finally was able to open the door by pressing the unluck button on the key fob and quickly pulling on the handle when it was cycling through the locking/unlocking procedure. Very strange. Glad I had the key fob on me and not in the car. Once in the car, I opened the passenger side from the interior handle, and everything went back to normal afterwards. So I would guess that it is indeed linked to battery issue. That's the wife's car, and it is a 2020 992 C2, equipped with an AGM battery, so not the same as yours but I would say it's still applicable.

I would suggest to check your battery terminals, see if they are tight enough and making good contact with the connectors. During my search on battery related issues, I've read that in some models of 992 there was an issue on the engine ground post that was causing battery drain. There was a TSB bulleting about it and it was posted somewhere on Rennlist. Not sure your car is concerned by that as it is recent but worth having a look. The TSB you're mentioning is regarding @siberian thread on the Connect low module version? After doing a VAL on my wife's car, it did not have a Connect module, so for my part I was not concerned by it.

westcoastj

Charger currently attached directly to the terminals. Going to keep an eye on it, will bring to the dealership.

OliverK68

Have you tried replacing the fob battery?

aggie57

Here are the service orders; hope this helps.

leloupgris

Thanks @aggie57.

So I took the car yesterday to drop my wife off. I had first to add in the customizable display the battery voltage. It was a 10-15min drive, in the city. To my surprise, the voltage was sitting at 12.7V. It was jumping up to ~14.4V on braking. It did not look like it was rev dependent, but more on load.
Once I was back, I hooked the PIWIS up and checked the battery parameters. Aging state was still 100%, and charging state was 80%. From what I've read, the BMS needs some time to adapt and learn the new battery. On a side note, the Auto Start/Stop worked when we stopped at a traffic light. I disabled it after seing it was working. I am not familiar with the 992 charging behaviour, but from what I've read, what I described above seems normal.

On the second drive when I went to pick up the wife an hour and a half later, it was sitting at 13.1V and again going up to above 14V on braking. I will keep monitoring it to see if everything it's in order.

On my other cars (997 and Wrangler), the battery is always at 14+V when the car is on. I know that for emission purposes and optimization purposes on the newer cars the charging is much more complicated, and will fluctuate a lot and kick in when the engine is not loaded. Interesting that on your car now it is always charging.

From your pictures, the first service report indicates that they updated the software version of the ConBox module to version 0412 as per the TSB 2229.5 (higher than normal current draw). My wife's car does not have that module, so that shouldn't be a problem in my case. I can see they also checked the engine ground strap (also a known issue).

On the second service report, it does not seem like they found the origin of the problem. It had an excessive current draw. They just auto coded all the modules and the closed circuit current draw went down.

Interesting readings! Thanks again.

I will probably check the current draws on both the 992 & 997 and see where I am at. I will keep monitoring the 992 to see if battery health/charging improves. I had quite a bit of issues with the 997 battery aswell. They're known to discharge the battery quite rapidly if not driven/maintained. I installed a bluetooth battery monitor on the 997 and will do the same on the 992. Very handy little devices.

westcoastj

My battery is now completely dead...won't charge on trickle charger, won't charge on a regular charger, voltmeter won't even turn on...WTF.

leloupgris

Lithium batteries have a safety feature that cuts them off when they go below a certain voltage (11 and something V, don't remember the exact number). Chargers won't start charging because they don't see any voltage at the terminals. You have to first apply a voltage of 12.somethingV to the battery (don't remember exactly how much, check on Google), to wake them up first. Only them you'll be able to charge it again. Check if that's the case with yours. Hopefully that's only that.

It's best practice with these cars to charge the battery connecting the negative cable to the designated bolt on the driver's side in the battery compartment, and not to the battery terminal directly. To be honest, I don't know exactly the reason but I've read a similar case than yours where the owner was charging it's battery by directly connecting to the terminals. The charger would see the battery full and stop charging. His battery went dead the same way yours did. Once he started charging it via the negative bolt instead of the negative terminal on the battery, the charger would correctly charge it. You may wanna try that after you manage to wake up your battery.

westcoastj

Thanks for the info. I guess that explains why my volt meter is not working. I've ordered a Noco Genius 5 charger with same day Amazon shipping, since the Porsche Charge-o-mat trickle charger doesn't seem to be up to the job. Will try on the bolt as you suggested to see if that makes a difference and will report back.

CZS

Might give this a try to see if you can 'wake' it up?

You Tube

BondJ

Connecting to positive and ground will keep the BMS in the loop as the battery charges, guaranteeing the ECU is aware of the battery state at all times. That’s how it was explained to me years ago. Never heard a convincing argument in contradiction. Seems like a good bet to wake up a LiPo

aggie57

Oh dear, seems I poked the bear .... car dead again on Saturday. Cranked slowly but would not start. Jump started it with the booster, used it fine through Saturday, it sat Sunday, Monday am same as Saturday - slow crank, no start, several error messages.

Called Porsche Irvine, sending it to them.....

leloupgris

Oh my... Sorry to hear that! Probably a parasitic drain on the battery again... Do you have anything "aftermarket that you leave plugged in? Phone charger, dash cam, radar detector..? Your battery was still charging at 14.5V when you took it on Saturday?

In my case, I continued monitoring my wife's car battery. I added a battery bluetooth monitor (This guy). It's very practical to follow up the battery state and charging behaviour of the vehicle. And that allowed me to know that her car has something going on with the charging system: took the car yesterday twice. First time battery was at 12.3V while cruising (when the car was off it was at 12.75, read from the bluetooth monitor, see picture below), only going up to 13+V when braking. Second time it was sitting at 12.9V-13V, and again going up to 13V+ when braking. The battery monitor reports a charging state of 75% knowing that I charged it fully a couple days ago. I found this chart on the internet (source: How far can you discharge an AGM battery?) that seems to indicate what I am seeing as a normal behaviour. I am not very familiar with AGM batteries, so I don't know. If anyone has an input on this, I'll be glad to hear.


AGM state of charge guide

Here is what my bluetooth battery monitor gathered for the day of yesterday and this morning before going to work:


AGM battery voltage monitoring on 15th and 16th of May.

You can clearly see the behaviour when the car is on and voltage goes up and down depending on braking. I am really wondering if this is normal behavior or it's something I should be concerne about.

Thanks for the information. Seems logical to me and it makes sense.

Did you manage to "wake up" your battery and charge it back up?

westcoastj

Yes, managed to wake the battery with a portable jump starter. All sorts of crazy warnings, but they all turned off. Battery has been on Noco Genius 5 (since my Porsche Charge-o-mat didn't seem to keep it chargged) now and seems okay, but today during the drive, voltage shows 13.3V which seems low, but no low battery warning (previously showed 14.4V while driving, but got a 12v low battery warning from PCM)....I have a dashcam installed but parking mode is disabled, shouldn't be draining when it's off...

aggie57

Thanks. Yes, still charging at 14.5. The only thing I had plugged in last week was an iPod Touch, but I disconnected that Saturday and the thing still went flat over the weekend.

But.....I took the car in Monday morning myself and guess what - was told that there's a related service bulletin due for the car related to the connect module. I didn't have @siberian 's DIY post handy so didn't ask the TSB number but sounds suspiciously familiar, especially as per that TSB the car was sending alarms via Porsche Connect both times I jump started it (Saturday and Monday mornings). Stupid of me not to take that with me I know, let see what s/w version they update the Connect module to.

One thing I will say though, for all the flak SoCal dealers get and even my own annoyances in the past, the Porsche Irvine service team in this case has been very helpful.