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Sorry if this has been discussed before. Im getting mixed advice from service people at my local dealer. Does anyone know if it's okay to use a trickle charger on a 2019 Cayenne ehybrid and if so, will a CTEK LiFePO4 work? Thanks in advance for your help.
I just read a fascinating article which triggered another research frenzy that reminded me of this thread.
Until today, I didn’t realize that Cayenne E-hybrids don’t have a starter nor an alternator. The high voltage (HV) battery starts the ICE by engaging a clutch on the HV electric motor. The HV battery also charges the 12V battery. The 12V battery powers typical 12V systems on the vehicle. Importantly, the 12V battery powers the coil packs that provide ignition in the ICE. A regular ICE vehicle is self-generating. The alternator provides power to the 12V battery which powers the starter and the coil packs. Not so with a hybrid.
If the high voltage battery is completely discharged or malfunctions, the ICE engine will not start. Jumping the 12V battery won’t work since it doesn’t power the starter. [EDIT: Audi describes a procedure for jump-starting via the 12V battery terminals to charge the HV battery. See Post #6 below.] If the ICE happens to be running when the HV battery fails, the ICE will continue to run with the 12V battery powering the coil packs until it is depleted. It would behave like a regular ICE vehicle with a failed alternator — you’ll get a few miles down the road, soon followed by misfires when under load, followed by sputtering and engine quitting.
So, to answer your question, I suppose you could use a CTEK to trickle charge your 12V battery. But it won’t really affect how your ICE starts. That all depends on your high voltage battery.
I just read a fascinating article which triggered another research frenzy that reminded me of this thread.
Until today, I didn’t realize that Cayenne E-hybrids don’t have a starter nor an alternator. The high voltage (HV) battery starts the ICE by engaging a clutch on the HV electric motor. The HV battery also charges the 12V battery. The 12V battery powers typical 12V systems on the vehicle. Importantly, the 12V battery powers the coil packs that provide ignition in the ICE. A regular ICE vehicle is self-generating. The alternator provides power to the 12V battery which powers the starter and the coil packs. Not so with a hybrid.
If the high voltage battery is completely discharged or malfunctions, the ICE engine will not start. Jumping the 12V battery won’t work since it doesn’t power the starter. If the ICE happens to be running when the HV battery fails, the ICE will continue to run with the 12V battery powering the coil packs until it is depleted. It would behave like a regular ICE vehicle with a failed alternator — you’ll get a few miles down the road, soon followed by misfires when under load, followed by sputtering and engine quitting.
So, to answer your question, I suppose you could use a CTEK to trickle charge your 12V battery. But it won’t really affect how your ICE starts. That all depends on your high voltage battery.
what an awesome summary - thank you! I love this sort of stuff!!!
I just read a fascinating article which triggered another research frenzy that reminded me of this thread.
Until today, I didn’t realize that Cayenne E-hybrids don’t have a starter nor an alternator. The high voltage (HV) battery starts the ICE by engaging a clutch on the HV electric motor. The HV battery also charges the 12V battery. The 12V battery powers typical 12V systems on the vehicle. Importantly, the 12V battery powers the coil packs that provide ignition in the ICE. A regular ICE vehicle is self-generating. The alternator provides power to the 12V battery which powers the starter and the coil packs. Not so with a hybrid.
If the high voltage battery is completely discharged or malfunctions, the ICE engine will not start. Jumping the 12V battery won’t work since it doesn’t power the starter. If the ICE happens to be running when the HV battery fails, the ICE will continue to run with the 12V battery powering the coil packs until it is depleted. It would behave like a regular ICE vehicle with a failed alternator — you’ll get a few miles down the road, soon followed by misfires when under load, followed by sputtering and engine quitting.
So, to answer your question, I suppose you could use a CTEK to trickle charge your 12V battery. But it won’t really affect how your ICE starts. That all depends on your high voltage battery.
Can you link to the article that has this info? Thank you.
Here goes!
No single source spelled it out — I deduced my conclusion after reading dozens of forums, websites, and engineering papers. The Excellence Magazine article, linked below, provides a good overview of Porsche Hybrid technology.
This Self Study Program for Audi Hybrids provided most of the technical details. Keep in mind, this is an Audi that uses a similar drivetrain. Cayenne details may be different.
Here’s a link to the 8.6 MB pdf file, too large to attach on this post: https://procarmanuals.com/wp-content...-A8-hybrid.pdf
Firstly, today’s research provided three new insights:
1. If your 12V battery is dead, you can’t charge the HV battery. The High Voltage Battery Regulation Control Unit is powered by the 12V battery.
2. Your battery charge gauge may be lying to you in order to enhance battery life. For instance, when the gauge shows 100%, actual battery state of charge (SOC) is only 80%. When the gauge shows 0%, you actually have 30% SOC.
This does two things. Over-discharging the battery can seriously damage it. Also, 30% charge provides a reserve to start the ICE, as the BMS will disconnect at 20% SOC. From Audi:
The charge level of the high voltage battery A38 is maintained at between 30% and 80% of total capacitance. The limited charge range extends the life of the high voltage battery considerably. The battery charge indicator in the instrument cluster display reads 0% or 100% .
Furthermore:
If the charge of the high voltage battery A38 drops to below 25%, starting capacity is now at a critical level. If the internal combustion engine fails to start at this charge level, the message "Vehicle cannot be started at this time. See owner's manual" appears on the instrument cluster display. If the charge level is below 20%, the high voltage battery is not permitted to discharge any more current. The internal combustion engine can no longer be started by electro-drive drive motor V141.
3. I was surprised to find a procedure for using a 12V source to jump-start a dead HV battery. I was wrong to say you can’t jump start a dead HV battery. This applies to Audis. I assume (but am not certain) the Cayenne is similar. From Audi:
Jump-starting the high voltage battery
If the instrument cluster display reads "Vehicle cannot be started at this time. See owner's manual", the high voltage battery must be charged by another vehicle or using a 12-volt charger.
Procedure:
• Switch terminal 15 on (I think this is the first click, or ACC position on the starter ****).
• Connect the jump leads or the charger to the jump start stud . . . (Several other steps, omitted for clarity) • After about a minute, the instrument cluster display displays the following message: "Preparing to start vehicle. Please wait…". • When the charge level of the high voltage battery reaches 35 %, the charging cycle is automatically terminated. • Since the charging cycle takes place when terminal 15 is "on", the charger should ideally have a charging capacity of between 50 and 70 A. • The vehicle automatically switches terminal 15 "off" after 30 minutes. This means that the charging cycle is also aborted. • The following message then appears on the instrument cluster display: "Startability restored. Vehicle can be started." • If the message is "Charging cycle aborted. Cannot start engine", the donor vehicle or the charger may not have sufficient charging capacity.
Here are my best references (among others) regarding e-Hybrid engine’s lack of a starter and alternator. Also reference for the HV drive motor used for starting the ICE. From Audi, link here: https://procarmanuals.com/vag-ssp-61...udi-a8-hybrid/
The term "electric machine" or "e-machine" is used instead of the the terms generator, electric motor and starter. Basically, any electric motor can be used as a generator. If the e-machine motor shaft is driven externally, it delivers electrical power as a generator. If the e-machine is supplied with electrical power, it functions as a motor. The e-machine of an electrical hybrid therefore replaces the conventional starter of the internal combustion engine and the conventional generator (alternator).
Electro-drive drive motor V141 is used for starting the internal combustion engine, while also allowing the vehicle to operate solely under electric power and assisting the internal combustion engine during acceleration. When it not being used as an electric motor, electro- drive drive motor V141 acts as a generator and supplies the entire vehicle with power.
I can’t find a reference to prove the coil packs are powered by the 12V battery. Can I get a gimme for that one?
No single source spelled it out — I deduced my conclusion after reading dozens of forums, websites, and engineering papers. See below for a few representative links:
This Self Study Program for Audi Hybrids provided most of the technical details. Keep in mind, this is an Audi that uses a similar drivetrain. Cayenne details may be different.
Here’s a link to the 8.6 MB pdf file, too large to attach on this post: https://procarmanuals.com/wp-content...-A8-hybrid.pdf
Firstly, today’s research provided three new insights:
1. If your 12V battery is dead, you can’t charge the HV battery. The High Voltage Battery Regulation Control Unit is powered by the 12V battery.
2. Your battery charge gauge may be lying to you in order to enhance battery life. For instance, when the gauge shows 100%, actual battery state of charge (SOC) is only 80%. When the gauge shows 0%, you actually have 30% SOC.
This does two things. Over-discharging the battery can seriously damage it. Also, 30% charge provides a reserve to start the ICE, as the BMS will disconnect at 20% SOC. From Audi:
The charge level of the high voltage battery A38 is maintained at between 30% and 80% of total capacitance. The limited charge range extends the life of the high voltage battery considerably. The battery charge indicator in the instrument cluster display reads 0% or 100% .
Furthermore:
If the charge of the high voltage battery A38 drops to below 25%, starting capacity is now at a critical level. If the internal combustion engine fails to start at this charge level, the message "Vehicle cannot be started at this time. See owner's manual" appears on the instrument cluster display. If the charge level is below 20%, the high voltage battery is not permitted to discharge any more current. The internal combustion engine can no longer be started by electro-drive drive motor V141.
3. I was surprised to find a procedure for using a 12V source to jump-start a dead HV battery. I was wrong to say you can’t jump start a dead HV battery. This applies to Audis. I assume (but am not certain) the Cayenne is similar. From Audi:
Jump-starting the high voltage battery
If the instrument cluster display reads "Vehicle cannot be started at this time. See owner's manual", the high voltage battery must be charged by another vehicle or using a 12-volt charger.
Procedure:
• Switch terminal 15 on (I think this is the first click, or ACC position on the starter ****).
• Connect the jump leads or the charger to the jump start stud . . . (Several other steps, omitted for clarity) • After about a minute, the instrument cluster display displays the following message: "Preparing to start vehicle. Please wait…". • When the charge level of the high voltage battery reaches 35 %, the charging cycle is automatically terminated. • Since the charging cycle takes place when terminal 15 is "on", the charger should ideally have a charging capacity of between 50 and 70 A. • The vehicle automatically switches terminal 15 "off" after 30 minutes. This means that the charging cycle is also aborted. • The following message then appears on the instrument cluster display: "Startability restored. Vehicle can be started." • If the message is "Charging cycle aborted. Cannot start engine", the donor vehicle or the charger may not have sufficient charging capacity.
Here are my best references (among others) regarding e-Hybrid engine’s lack of a starter and alternator. Also reference for the HV drive motor used for starting the ICE. From Audi, link here: https://procarmanuals.com/vag-ssp-61...udi-a8-hybrid/
The term "electric machine" or "e-machine" is used instead of the the terms generator, electric motor and starter. Basically, any electric motor can be used as a generator. If the e-machine motor shaft is driven externally, it delivers electrical power as a generator. If the e-machine is supplied with electrical power, it functions as a motor. The e-machine of an electrical hybrid therefore replaces the conventional starter of the internal combustion engine and the conventional generator (alternator).
Electro-drive drive motor V141 is used for starting the internal combustion engine, while also allowing the vehicle to operate solely under electric power and assisting the internal combustion engine during acceleration. When it not being used as an electric motor, electro- drive drive motor V141 acts as a generator and supplies the entire vehicle with power.
I can’t find a reference to prove the coil packs are powered by the 12V battery. Can I get a gimme for that one?
I can’t find a reference to prove the coil packs are powered by the 12V battery. Can I get a gimme for that one?
with out an alternator is there really any other choice? I mean I guess they could power them directly off the HV battery - but why - 12V powers everything "legacy" from the supply chain of off the shelf parts - and have the HV battery "back charge" the 12V battery - seems like the most straight forward choice and design…no reason to pull the HV battery directly into that when existing parts and designs will do the trick…
^^^ Agreed. That was my reasoning, as well. I would have liked to post a schematic to prove it but can’t find one.
Just found some more info from Porsche GB. When you charge the high voltage battery the 12V battery is also trickle charged. So to answer OP’s question — you shouldn’t need a CTEK as long as you keep your HV battery on the charger.
^^^ Agreed. That was my reasoning, as well. I would have liked to post a schematic to prove it but can’t find one.
Just found some more info from Porsche GB. When you charge the high voltage battery the 12V battery is also trickle charged. So to answer OP’s question — you shouldn’t need a CTEK as long as you keep your HV battery on the charger.
So I woke up this morning to our 22 E-hybrid completely dead this morning. It sat in the garage all weekend unlocked and plugged into the charger (as I saw that this should trickle charge the 12V battery). It was last driven on Friday. Wife had to leave for work this morning, so she took my car instead. Will have to jump start it when she gets back from work.
Now I'm wondering if we should be locking the car. The keys are kept about 20ft away inside the house, could that the issue? I think I will still keep the CTek trickle charger on. It makes me wonder if the Lithium 12V is defective.
Also, on a few occasions the alarm has randomly gone off and I noticed that the times when we do lock the door, the comfort access will not work in the morning. That sounds like the accessories are going into sleep mode.
Troublesome electric issues on a new car.
Last edited by Lphiesmacks10; 02-07-2022 at 06:09 PM.
That sucks. Porsche engineer was quoted saying the e-Hybrid is the most complex vehicle ever designed by Porsche. And that’s saying something!
I’m curious to see how jumping with 12V battery works out. Will it work as described in the procedure in Post #6? Also wondering if unplugging HV charger and reconnecting works. If not, that would confirm the 12V is needed to run the HV charging circuit. Could you connect a booster to the 12V to get the HV charge circuit working? Lots of ways to attack this. Watching for updates.
That sucks. Porsche engineer was quoted saying the e-Hybrid is the most complex vehicle ever designed by Porsche. And that’s saying something!
I’m curious to see how jumping with 12V battery works out. Will it work as described in the procedure in Post #6? Also wondering if unplugging HV charger and reconnecting works. If not, that would confirm the 12V is needed to run the HV charging circuit. Could you connect a booster to the 12V to get the HV charge circuit working? Lots of ways to attack this. Watching for updates.
Due to the car being completely dead, we can't even disconnect the charger. You have to push a button to unlock the charger and that doesn't work. The PMCC does show a 100% state of charge though. Normally there is a green light on the charge port, but that is off. Not sure if it's cause the car is at 100%. Normally it'll flash green during charging.
I tried to put the trickle charger on, had to hold down the reset button to try to open up Under Voltage Protection. The first step would flash briefly and go off and the ready green light starts to flash. So at this point the trickle charger can't even do anything. Dont have a booster, so will need to wait for the wife to get home to jump
Edit:
Also reading the manual now and it says not to use boosters with a lithium battery.
Last edited by Lphiesmacks10; 02-07-2022 at 01:12 PM.
hmmm - not quite the same - seems like a dealer visit is in order - not sure how to start the Cayenne in this state…
jump charged the 12V battery successfully. As soon as I attached the jumper cables the electrical system started up, even before I started up the donor car. left it on for a bit and turned the **** to S+ to start the engine. Now that I think of it, that probably doesn't do anything cause allegedly the E-hybrids don't have an alternator right?
Got the Ctek hooked up now and it's already at Stage 5.
Got the "12v battery is low. Please charge battery" message on the PCM and pulled these codes.
07-06-2020, 02:12 PM
eHybrid charging
