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I would say your battery has some weak cells, since when the voltage is low when the engine is off, and the voltage goes up to a charging 13+ volts when you turn the engine on..
Anybody who has the service repair manuals should have a LiFePO4 voltage chart with the normal voltages and corresponding capacities left..
Did you have the dealer apply the TSB fix that overcharged and damaged the batteries?
It may not apply to you, since you seem to have been monitoring the battery voltage and charging voltage..
The dealer applied a battery related TSB back in June but not sure what it does actually. The car started fine this morning and no warning or anything but the garage is a bit cold at 59F but doubt the temperature is the issue. Currently the battery tender is in Stage 5 (final charge with reduced current with approx. 98% battery capacity). I've unplugged all sockets (radar detector, dashcam, USB iphone cables) and let the battery tender to charge the battery to full and unplug it overnight and see what it will look like tomorrow.
Last edited by Silververtu; 11-29-2023 at 02:28 PM.
The dealer applied a battery related TSB back in June but not sure what it does actually. The car started fine this morning and no warning or anything but the garage is a bit cold at 59F but doubt the temperature is the issue. Currently the battery tender is in Stage 5 (final charge with reduced current with approx. 98% battery capacity). I've unplugged all sockets (radar detector, dashcam, USB iphone cables) and let the battery tender to charge the battery to full and unplug it overnight and see what it will look like tomorrow.
98% Sounds pretty promising.. Hopefully, the battery will work fine afterwards..
98% Sounds pretty promising.. Hopefully, the battery will work fine afterwards..
Yea, went to Stage 7 (maintain voltage) after work. Took the car out for a short drive, no battery error message. Gonna let the car sits overnight without battery tender and see what it will be like tomorrow.
Below is the historical voltage these 2 days, the voltage was dropping throughout the day (never seen it before). On the other hand, the sensor couldn’t sense the voltage until I started the car up this morning and at the same time the battery was still being charged at full current after entire night (also never happened before).
Your top graph (28 NOV) shows a notable voltage drop between 0700 and 2100 — just 15 hours. It then recovered in just a few minutes at 2130 — as if a parasitic load occurred at 0700 then stopped at 2130. Mine took a week to drop a similar amount:
Your top graph (28 NOV) shows a notable voltage drop between 0700 and 2100 — just 15 hours. It then recovered in just a few minutes at 2130 — as if a parasitic load occurred at 0700 then stopped at 2130. Mine took a week to drop a similar amount:
The voltage actually started dropping since Nov 27 (no idea why as the car was sitting for 2 days which happened very often and voltage was never dropped). My wife used the car for a few minutes on Nov 27 which brought the voltage above 13V, then it started dropping until I connected the battery tender to the car at 2130.
Make sure you check for any aftermarket Lo-jack type tracking modules. The morons at Porsche Bethesda install one on every car they sell without asking for permission. I bought the car CPO so it should have been brought back to "factory specifications" so they should have removed that **** but they didn't. Eventually the battery in these modules dies and it starts draining the 12V. That's what happened to my wife's GTS back in the summer.
Last edited by matthewr87; 11-30-2023 at 09:05 AM.
Just to report back, the battery seems to go back to normal now, holding charge at 97% and voltage remains above 13V.
My mind has not calibrated to accept spending $2.5k on a car battery that last about 4 years. Only change car battery twice in my life and those batteries were 10 years old and less than $300 OTD.
Last edited by Silververtu; 11-30-2023 at 10:04 AM.
Make sure you check for any aftermarket Lo-jack type tracking modules. The morons at Porsche Bethesda install one on every car they sell without asking for permission. I bought the car CPO so it should have been brought back to "factory specifications" so they should have removed that **** but they didn't. Eventually the battery in these modules dies and it starts draining the 12V. That's what happened to my wife's GTS back in the summer.
Yea, your Lo-jack issue popped up in my mind as soon as i saw 0% on the app. I was thinking what caused the battery drain. I unplugged dashcam (dashcam battery powered and the battery is connected to trunk socket which shuts off after 10-30 mins), radar detector (hardwired to ignition on fuse) and all USB cables to eliminate potential drain.
Side question, are you in the Fulton area? Always see a Cayenne GTS coupe in my neighborhood that looks exactly like yours.
Last edited by Silververtu; 11-30-2023 at 10:02 AM.
You may keep all your gadgets hooked up, provided you have a battery maintainer (Porsche or CTEK with Lithium option) plugged into your cigarette lighter socket overnight. Just don't let the car sit excessively without the maintainer. For me it is a habit to use it all the time-all my AGMs lasted at least 7 years. Test of time will show whether this is true for LFP battery.
You may keep all your gadgets hooked up, provided you have a battery maintainer (Porsche or CTEK with Lithium option) plugged into your cigarette lighter socket overnight. Just don't let the car sit excessively without the maintainer. For me it is a habit to use it all the time-all my AGMs lasted at least 7 years. Test of time will show whether this is true for LFP battery.
Don't they recommend to not keep your charge above 80% to extend the battery life of LiFePO4 and Lithium? and to not let it discharge below 80% of DoD (Depth of Discharge)?
Chargers that constantly charge the battery in "float" will eventually damage the Lithium batteries.
Smart Lithium battery charges stop the charging until the voltage drops, it waits for a determined voltage drop to restart the charging..
I am sure the Porsche and CTEK batteries do this correctly, but charging the battery to full charge every night, I don't know if that is a good idea..
Some LiFePO4 batteries specs claim around 5,000 charge cycles at 80% and around 2,000 charge cycles at 100%.
I wonder what the Porsche and CTEK Lithium chargers do.. I can't remember what mt Porsche chargers stated in the manual, if anything was mentioned..
Don't they recommend to not keep your charge above 80% to extend the battery life of LiFePO4 and Lithium? and to not let it discharge below 80% of DoD (Depth of Discharge)?
Chargers that constantly charge the battery in "float" will eventually damage the Lithium batteries.
Smart Lithium battery charges stop the charging until the voltage drops, it waits for a determined voltage drop to restart the charging..
I am sure the Porsche and CTEK batteries do this correctly, but charging the battery to full charge every night, I don't know if that is a good idea..
Some LiFePO4 batteries specs claim around 5,000 charge cycles at 80% and around 2,000 charge cycles at 100%.
I wonder what the Porsche and CTEK Lithium chargers do.. I can't remember what mt Porsche chargers stated in the manual, if anything was mentioned..
At the bottom is a link to the copy of manual that I was able to pull from the internet re Porsche Charge-o-Mat (it's a CTEK product). I only follow what I read using technical references from reputable battery manufacturers. Just as an fyi, I have a boat that is equipped with LFP auxiliary/house batteries (600 Ah) with on-board charger to supply electricity through an inverter when offshore. Here is a quote from the manufacturer:
Can a Mastervolt battery charger remain connected throughout the winter?
Yes, that’s not a problem. Mastervolt battery chargers are safe to use and it is even better for the batteries themselves. The charge voltage is regulated in accor*dance with the battery temperature to ensure the batteries remain in optimum condition, increasing their lifespan. The 3-step+ charging method ensures a monthly absorption cycle so the battery stays active.
Continuing our discussion:
I'm applying the same logic when charging my car battery. Charge-o-Mat is designed to provide the same charging algorithm (bulk/absorption/float phases). As you've stated in your post above, smart maintainers provide this algorithm and we need to trust they function properly, otherwise what is the point of using them. The "float" stage simply means that battery is left "alone" when fully charged and will kick in again once sufficient drop in voltage is detected. I agree that you may find info on the internet stating that having Lithium batteries 100% charged is not good. I don't have expertise to argue about this, however I believe modern LFP batteries have built in software driven regulators that will ensure charging process is done correctly, provided your charger is designed for them. I see cars connected to maintainers at my local Porsche dealer in the showroom waiting to be sold, which sometimes require months. I follow this practice myself, perhaps a bit to an extreme (we are all different personalities), but I don't drive everyday. I may have a talk with the technical advisor at my Porsche shop about this battery topic, but any good expert on modern lithium batteries would be a good source.
P.S. Following my post, I had a chance to spend quite a bit of time on the phone with the Porsche service consultant (level above SA), discussing some service related topics-I brought up the topic of the LFP battery. He is aware of the issues, particularly on early models. Here is the scoop: the capacity of 60Ah is a lot less than what AGM batteries provided. Compared to AGMs, they will drain faster due to lower capacity, so clearly do not let the car sit for prolonged period of time (1 month or so) without a maintainer designed for Lithium battery. It is possible to boost drained battery with a regular booster, but to do it properly, one should use factory proprietary booster due to the fact that battery shuts down after 90% discharge. The battery damage does occur when using generic boosters (even if designed for Lithium) due to Porsche/Volkswagen software specifics to wake up the battery correctly. In summary, it is an expectation that we as drivers make sure our batteries are properly maintained. This is a tall order in my opinion for regular consumers like ourselves and I expect that the battery issue will continue to plague small part of Porsche community. The problem is the cost of the battery, otherwise people would be less up in arms about it.
Last edited by lucian95; 12-01-2023 at 12:29 PM.
Reason: link to attachment left out
As a complete side note, I received my 24 TGT on 11/16 and immediately started getting "chassis" errors and it was determined that the 48volt battery as defective!! Was told one cell was not holding a charge, anyway, I am still waiting for a new battery to be sent from ATL. Supposedly, it is a unique battery to vehicles that have 4 wheel steering. Needless to say, not an optimal start to an ownership experience.
Plus the brand new Cayenne that I have as a loaner, after every start up and about 5 minutes of driving, it gives four error messages, but it's safe to drive!! LOL Good job Porsche!!
At the bottom is a link to the copy of manual that I was able to pull from the internet re Porsche Charge-o-Mat (it's a CTEK product). I only follow what I read using technical references from reputable battery manufacturers. Just as an fyi, I have a boat that is equipped with LFP auxiliary/house batteries (600 Ah) with on-board charger to supply electricity through an inverter when offshore. Here is a quote from the manufacturer:
Can a Mastervolt battery charger remain connected throughout the winter?
Yes, that’s not a problem. Mastervolt battery chargers are safe to use and it is even better for the batteries themselves. The charge voltage is regulated in accor*dance with the battery temperature to ensure the batteries remain in optimum condition, increasing their lifespan. The 3-step+ charging method ensures a monthly absorption cycle so the battery stays active.
Continuing our discussion:
I'm applying the same logic when charging my car battery. Charge-o-Mat is designed to provide the same charging algorithm (bulk/absorption/float phases). As you've stated in your post above, smart maintainers provide this algorithm and we need to trust they function properly, otherwise what is the point of using them. The "float" stage simply means that battery is left "alone" when fully charged and will kick in again once sufficient drop in voltage is detected. I agree that you may find info on the internet stating that having Lithium batteries 100% charged is not good. I don't have expertise to argue about this, however I believe modern LFP batteries have built in software driven regulators that will ensure charging process is done correctly, provided your charger is designed for them. I see cars connected to maintainers at my local Porsche dealer in the showroom waiting to be sold, which sometimes require months. I follow this practice myself, perhaps a bit to an extreme (we are all different personalities), but I don't drive everyday. I may have a talk with the technical advisor at my Porsche shop about this battery topic, but any good expert on modern lithium batteries would be a good source.
P.S. Following my post, I had a chance to spend quite a bit of time on the phone with the Porsche service consultant (level above SA), discussing some service related topics-I brought up the topic of the LFP battery. He is aware of the issues, particularly on early models. Here is the scoop: the capacity of 60Ah is a lot less than what AGM batteries provided. Compared to AGMs, they will drain faster due to lower capacity, so clearly do not let the car sit for prolonged period of time (1 month or so) without a maintainer designed for Lithium battery. It is possible to boost drained battery with a regular booster, but to do it properly, one should use factory proprietary booster due to the fact that battery shuts down after 90% discharge. The battery damage does occur when using generic boosters (even if designed for Lithium) due to Porsche/Volkswagen software specifics to wake up the battery correctly. In summary, it is an expectations that we as drivers make sure our batteries are properly maintained. This is a toll order in my opinion for regular consumers like ourselves and I expect that the battery issue will continue to plague small part of Porsche community. The problem is the cost of the battery, otherwise people would be less up in arms about it.
Thanks, good information..
The more we know about our LiFePO4 battery brand specs (problematic LGChem brand in this case), and how they are supposed to be correctly charged/maintained, the longer our batteries will last..
Don't they recommend to not keep your charge above 80% to extend the battery life of LiFePO4 and Lithium? and to not let it discharge below 80% of DoD (Depth of Discharge)?
You can full-charge lithium iron batteries without issue. On the "LFP" standard range model 3, Tesla recommends setting the charging limit to 100%. They recommend setting the limit to 80% in their cars with other lithium ion batteries.
11-29-2023 | 02:27 PM
