Procedures for accessing the battery compartment for a 958 Cayenne ( 2011 2012 2013 2014 ). They are different that the earlier Cayenne models!

Suffice it to say that Porsche probably did the 958 crowd a favor by learning from their past battery compartment designs. It is different than previous Cayenne models. I had been trying to find workshop instructions for the procedure and not even All Data DIY had one. So with that, I made this one.

My battery just passed its four plus year birthday recently and I get a bit nervous when a battery is around 4 years old. My Porsche service writer said that these are AGM batteries so I hooked up my AGM charger and it said that my battery was at 50%. Hmmmm? Although I did not change out the battery, I am now a lot more comfortable with the idea when it is time. I absolutely hate trying to learn a completely new procedure when one does not exist when it is cold, and batteries are notorious for dying when it is cold. So I let the charger run and decided that I might as well figure out how to access the battery compartment.

Tools:
- Small flat head screw driver to remove 4 bolt cover trim pieces
- Triple square bit 3/8 drive size 10 and 3/8 ratchet
- Torx bit size 25 and ¼ ratchet
- Sharp box cutter or knife
- 10 mm combination wrench for the battery terminals
- 10 mm socket with extension for hold down clamps

Battery. My factory battery is a VARTA 7P0 915 195 C, Size H8, AGM. I plan to stick with AGM when it is time to replace the battery. I do not know if an H9 will fit in the battery compartment. If you want to stick with Varta, it has been stated by others that a VW dealership has them at about $200. You should confirm with the VW dealer whether or not that particular dealer and any VW dealer will honor the warranty AND doubel check the manufacturing date of any battery that you buy. Les than 6 months is my rule of thumb on AGM.

Safety. Folks, batteries are dangerous. They can be used to arc weld with in emergencies. That means if you complete a circuit with a watch, a ring or a tool, it starts weldin’ and meltin’. People have lost fingers. Pay attention to what you are doing. Take the jewelry off.

I'll leave it to your preferences as to whether or not to provide an alternate 12 volt source to the vehicle to retain your settings if you are changing the battery. I'm will not use a battery charger as the 12 volt source because I have seen some surpass 16 volts with no battery hooked up. I used my charger simply because I wanted to make sure my new to me used Cayenne's battery had a full charge and I would be using the seat adjusters while investigating how best to access the compartment.

1. Familiarize yourself with the driver seat’s wiring harness underneath. You will need to manage it carefully when it is time to tilt the entire seat assembly backwards.
2. Run the driver’s seat full forward and the back rest full forward. This is important in a few steps.
3. Using a small bladed screw driver remove the two rear bolt cover/trim pieces. Press the end in gently and it will release exposing the size 10 triple square headed bolts.
4. Using the size 10 triple square bit, remove the two bolts.
5. Run the driver’s seat full to the rear and do not adjust the back rest which should be full forward.
6. Using a small bladed screw driver remove the two front bolt cover/trim pieces. Press the end in firmly and it will release exposing the size 10 triple square headed bolts.
7. Using the size 10 triple square bit, remove the two bolts. Take care that you control the tilting of the entire seat as it could place undue strain on the wiring harness. The seat back will rest against the bench of the back seat. If you think there is too much strain, the harness is tied into the deck with a friction fit. Simply grab it and move it back and forth while lifting and it will release. You still need to be careful because there is no protection for the harness connectors now. Even if you disconnect the three harness connectors, the seat belt is still attached.
8. You will see a large piece of plastic trim that outlines the access to the battery compartment. If this is the first time that the compartment will be accessed, you will find that sections of carpet underneath the plastic have been precut. You will need to release the almost cut through sections by either stressing the carpet a bit or use the box cutter. I used both, but be very careful with the box cutter as there are wires running underneath.
9. With the seat tilted back and the carpet lifted, the battery cover is now visible.
10. Release the spring clamps at each corner.
11. To remove the cover, you will need to reach underneath the cover in the back and lift it over the case so that it can slide backwards a bit. Doing so will allow the front of the cover to clear a metal lip.
12. If I were to remove the battery, I would remove all jewelry, remove the negative ground cable first, followed by the positive cable. If I have a 12volt source hooked up to retain the cars memory settings, I would wrap the end of the positive terminal with plastic to prevent a short should the positive terminal come in contact with any grounded surface. As to a 12volt source, I would not use a battery charger because it is NOT a power supply. I bought a 12 volt supply OBD2 cable off Amazon and will use it when required. However, the owner's manual has the car reset procedure listed and it's not complicated at all.
13. With the cover removed, you can see the front left corner hold down clamp and the main hold down clamp also on the left side.
14. To lift the battery out, you may need a helper to lift the seat but again watch out of the wiring harness. Here, you might have to disconnect the three harness connectors. Be careful. One of them is airbag related. It appears that it is best to lift the front of the battery out first and then slide the whole battery out. Yep, it's heavy. When installing the replacement battery, if there are safety caps on the terminal, leave them on until you have the battery safely in its compartment and clamped back down.
15. Once installed, you are good to go to reinstall the clamps, the positive cable followed by the negative cable and backwards through the procedures.
16. Based on unverified information (PWIS or published shop manual) I believe that the seat mounting bolts are at 37 ftlbs. I saw no loctite remainder but blue loctite would not hurt anything as I suspect this area won't be accessed except every 4-8 years.

 

Looks great, one last step is battery registration after replacement... This needs to be done with pwis

 

If you connect a spare battery connected to the +/_ posts under the hood, do you still need to do battery registration with pwis? isn't there a way to reset the car without pwis?

Great write up!

 

Is the battery registration only done with PWIS?

 

Battery "registration" tells the charging system that you have a new battery and to adjust the charging parameters to match it. So - saving the old one isn't what you're looking to do (it is saved even without the 12V source connected.)

Dunno if Durametric can do this or not - will have to look. It would seem like a very useful function for it to have.

 

One or two small additions:

If you are really afraid of shorting things out, and don't mind having to teach all the windows, sunroof, blinds where their fully closed positions are.. there is a master ground disconnect on the 958. I thought to look for it because there was one on the 955.

Right in front of the seat pedestal there is a small hatch. It pulls out at the top, then folds over toward the pedals. Under that hatch is the master ground connection. One big nut - and you can kill power to the entire car. This is best done after you have the seat unbolted and tipped back.

I only found it necessary to cut one piece of carpeting. The rest of the bits that weren't cut were only about 1/8" wide, and easily pulled apart. It was only at the very rear nearest the door that I had to cut anything, and sharp scissors worked just fine.

The battery IS a vented battery. The Duracell replacement battery I got from Batteries+ didn't come with a vent kit, but that was OK since the factory vent pipe fit right into the vent hole on the new battery. There is another vent hole at the rear end of the battery that must be plugged up (you can pull the plug out of the old battery using a self-tap screw.)

The dimensions of the battery and specifications are exactly the same as what I took out - the only difference I could see was the old one was made in Austria, and the new one in the USA. Looking at various offerings in this size AGM battery from different vendors I came to the conclusion that there are two actual manufacturers in the US. One makes all the black-cased ones (AC-Delco, Autozone, PepBoyz, Duracell), the other makes the two-tone case ones. The plastic cases are IDENTICAL right down to the **** for the injection molding. After seeing this - I opted for the Battery's+ one since (1) it was almost the cheapest (2) a store near me had it in stock, with a 10% discount if I ordered it on-line and picked it up in the store.

The battery is one heavy sucker (about 60lbs) and awkward to get out and back in. I'm oldish, and I managed, but if you're a 50lb weakling, call someone stronger when you get to that point.

I did use blue 242 loctite on the seat bolts, just because. And I found out what the piece of plastic kicking around in my glovebox was for - it was one of the covers for the rear bolts.

The corner clamps are fiddly to get released until you figure out how to do it. If you have slim fingers you can reach down and pull out on the bottom of the sheet-metal bit. If not - you can use a screwdriver to push in on the top of the sheet-metal bit. Getting them back on was pretty simple. Put the wire part over the top, then push in the sheet-metal bit with your fingers.

J.R. - thanks for the DIY!

PS: I also discovered that there is a nice little fold-out drawer in the front of the seat. I can't recall ever seeing that mentioned, on a forum, or in the Cayenne books. Dunno what I'll put in it, and have to see if the passenger side has one too (in Europe the passenger side - that's where the mandatory fire extinguisher lives.)

 

Awesome posts! Thanks for tip on removing those clamps! I just wanted to add a couple things.
The triple square bit size 10 listed for a necessary part is kind of hard to find but a necessity. I tried to get by with a torx or hex but they don't work. I called Ace Hardware, they never heard of a triple square bit. I called O'reilly Auto Parts, same thing! He said they might have a "12 point bit" so I just went to look. Sure enough on the shelf was a set for $6 of triple square bits, None of the employees there had heard of it or even knew how to use it as it needs a 1/2 hex head driver. I used the 1/2' universal multipointed Craftsman socket to drive the triple square bit and it worked great.
BTW, I used a battery jumper clamped to the front terminals while I changed the battery and had no memory issues at all, everything was saved. Thanks again for a great write up!!

 

As fate would have it, I had to change the battery. I have noticed over the past couple of months memory drops and the last straw was the alarm going off. I checked the resting battery voltage and it was 12.18v. Not good. That is barely 50% charged for an AGM. Alternator was putting out well over 13.8v.

Picked up a H8 AGM from Advance Auto and with their 20% online coupon, the price was $151 down from $189. Let them keep their one dated 5/2015 and walked out with the 6/2016. I swear it looks just like a Varta. Vent line hook up was exactly the same too.

I used an OBDII connector with a 12v connector at one end to retain memory. The readaptation procedures in the owner's manual and AllData were straight forward. I saw zero mention of a PIWIS requirement to set battery age or date but next time I see my dealer tech I will ask.

My factory Varta battery was stamped 35/10. I got 6 years out of it. Not bad. I had hoped for more since it wasn't living in the engine compartment and was AGM. But, it was suffering from a slow death. Probably sulfination from all of the short drives and the starts and stops. $2.50 per month for a battery. Not bad. At least it didn't leave my wife stranded.

 

Just wanted to say thank you for this write-up. Just changed out the battery on my '12 Cayenne Turbo and relied heavily on this post to make it through. Got to admit that it was a tad tougher than I thought it would be but I had the correct tools, stuck with it and now she works great (aside from the PSM Error) that's now on the dash... but I read in manual that is common after battery change and that driving for a little bit should make it go away (I hope). Anyway, just wanted to say thank you for taking the time to write the post.

 

Great write up. Good tip of connecting a battery so not to loose memory.
I used my trailer winch battery.

For tools, go to Snap-on, or Amazon.

 

Great post. The only one for the newer Cayenne models. I think in the early models you didn't have to remove the rear seat bolts. As I followed a 08' tutorial I didn't manage to tilt back the seat.

The problem in my case is that the battery is completely dead, tried charging it for 2 hours but did nothing, I don't have power at all, not even hazard lights work. The reading on the under the hood terminals is 1v. The confusing bit is that after I charged it for 2 hours it would show 13.6v in the terminal but still had no power at all.

Anyways, where I'm trying to get is that I need to find a way to manually move the seat forward so I can be able to remove the rear bolts. Anyone has any suggestions ? I have been failing to remove the seat for the past 2 days and I can't take the car to a service since it is parked in such a way that is impossible to be towed, and to top it off the electric handbrake is on.

Awaiting any sort of help!

Radu
'15 Cayenne S 3.6l Gas

 

Thanks for posting this procedure. I hope I don't need it for a few years.

 

Power the system with another battery/vehicle, long enough to move the seat. The factory service manual states:Those being the points up under the front hood, where you'd connect jumper cables from another vehicle.

If a battery is bad it's possible for it to retain some amount of voltage but be unable to deliver any reasonable amount of wattage. As in, test it with no load and you might see a decent voltage value. But put any kind of load on it and it drops off to nothing.

 

Your point about removing rings and watches before touching the battery is a valid one. I learned the hard way when removing a battery from a BMW. Still have a scar and not all the feeling in one of my fingers. Go ahead and laugh, you can't make me feel anymore stupid than I did when I arced a wrench to my hand.

 

I've seen pictures of the aftermath. Filed under "things you can't un-see, but REALLY wish you could". Ugh, it can get really BAD if that much amperage shorts out and heats up the metal in a ring. I've taken to just not wearing mine anymore, too many close calls with all kinds of different tools. I've heard there's such things as silicone wedding rings, but haven't gone that route.