ct14

Today I wanna share with everyone how we repaired a Taycan with the so popular "Electrical System Error" by opening and replacing two battery modules inside the HV battery. First of all there's several disclaimers I wanna make.

1. Whatever you do is at your own risk. If you f*** up you could cause a massive fire, could shock yourself to an instant death. I won't be responsible for anyone's Darwin Award while trying to fix their Taycan...

2. Related to point one, we are based in Thailand, where we have 50 daily road deaths mostly from motorbike riders who don't wear helmet at speeds well over 100km. People here think the exact same about PPE, so you will notice my staff are wearing very little PPE. It's a lost battle for me, they refuse to wear it and I have to constantly be on top of them reminding them every minute.... If you try this repair yourself you should use the appropriate PPE (1kV safety gloves, 1kV safety boots, facial cover) and the appropriate insulated tools (such as VAS6762). This post is about repairing a Taycan battery, not about how to safely handle an HV battery. Don't be an *** about it.

Well, the first step in this repair is of course diagnosis. Use PIWIS3 or PIWIS4, those "generic tablets" won't get you far in repairing a Taycan. In this case we got the following error code:





"Cell voltage difference too high" - self explanatory really. Every module inside the battery must be perfectly balanced to the same voltage value up to at least two decimal values with a very minor tolerance margin. The same applies to each pouch cell inside each module.
From the code above we can ascertain at least one cell in at least one module inside the HV battery has passed on to a better life.

Let's remove the car's HV battery from the car. Easy peasy. Follow Porsche's manual. (It says you need some fancy hydraulic trolley to support the battery - but in reality 4 wood pallets will do). '

Step 0: De-energize HV system. Remove all body panels underneath the car.

Step 1: Drain the coolant. Disconnect one hose going to the radiator at the front of the car, disconnect the two hoses going into the HV battery at the front, and then disconnect one hose going to the motor at the rear. Pry the hose lock with a flat screwdriver it will come out.

Step 2: Remove the lining in the trunk, there is a lid which you can open and gives you access to the HV connector for the rear motor. Remove the 3 screws and undo the connector.





Step 3: Undo the HV connector at the front of the battery + 48V connector (pictures attached)


Step 4: Remove all the bolts holding the battery to the frame. Including 4 screws that bolt the battery to the rear subframe (and the earth wire, next to the rear right wheel)



Congratulations, now you got the battery out of the car:



Step 5: Once the battery is out of the car, if it's a battery plus you will have 3 extra modules on top. Remove the lid for those 3 modules using an oscilating machine like this one (be careful not to go too deep inside the battery). Then pry the lid open, but don't destroy it. We will be reusing the lids.



Step 6: Remove the nuts for the BMS module and disconnect it, then upon opening the lid for the 3 extra modules, remove all the HV wires connecting the three extra modules to the inside of the battery. Then proceed to remove the modules together with their container structure.




Step 7: Use the oscilator tool to remove the battery's main lid. It works exactly the same as the lid for the 3 modules on top.




Step 8: Congratulations you've opened up the battery.



Step 9: Grab yourself a multimeter that can measure at least two decimal places DC voltage up to 40V and measure the voltage of each module independently. Like this:


As you can see, all modules in this battery were within the range 24.47V to 24.50V... except for two modules which had dropped to 23.7V and 24.19V respectively. These modules are bad (pouch cells dead inside) and must be replaced.

Grab yourself two replacement modules, balance them to exactly the same voltage as all the others (anything between 24.47V and 24.50V). Put them back on the battery.



Reseal the battery using PU sealant and tightening the screws to the correct torque. After you are done sealing the battery, you must pressure test it to ensure it is airtight using


Repeat everything in reverse to put the battery back in the car. Then use PIWIS3 to code the new module's Serial Number and then do the procedure to unlock the HV battery. Your Taycan will be fixed












If somebody's got any questions feel free to ask me.

PS: Don't ask me to provide Taycan workshop repair manual for free. I paid a lot for it and I shared enough already. Don't bother about the manual.

d00d

Nice work!
Please let me know where you got your PIWIS if you can, thanks.

ct14

Fortunately, this isn’t the USA over here ….

At the end of the day while you moan online the customer is driving his Taycan

ct14

It is an original PT3G VCI paired with a cloned version of the software. Cracked. Not good for PPN tho.

ct14

so you’re a pedophile?

ct14

And you just keep on becoming a clown 🤣🤣🤣🤣

DerekS

It was an interesting, if scary, post on the process.

It would be nice if US Porsche dealers would learn to do this module replacement instead of keeping the car for months waiting on a new battery.

NF4710

Thank you for posting this! Certainly an interesting read. Let me apologize for our Taycan village troll. He will stop at nothing to brandish his arrogance,

N

pjazz

Thanks for the post. If you don't mind me asking what was the man hours for this repair, and price of replacement parts?

weberlukas74

Wow, thanks for sharing your detailed experience with the Taycan battery module replacement! It's always inspiring to see enthusiasts tackling such complex repairs and sharing their knowledge with the community. Your step-by-step guide is impressive, and your disclaimers show a good balance of responsibility and practical advice. Safety first, right?

mchrono

Wow I think you must be the 1st independent shop ever to perform this! Big congrats!

I get the replacing and balancing (bringing up to the same voltage) the bad cells, but what is the story behind "code the new module's Serial Number and then do the procedure to unlock the HV battery."

Why do the modules have serial numbers and why are they "locked"? This seems like unnecessary steps.

Can you share the steps in PIWIS to code and unlock?

ct14

It's around 30 hours of work. The cost of each module was around $1,830 (converted from local currency into USD).

ct14

I thought this was an easy job... We have also retrofitted PB+ to a standard battery. And converted Japan Taycan Chademo into normal Taycan Type2... That's what I'd call difficult lol...

Each of the modules has its own serial number, kind of like a VIN for battery modules. This is stored in Porsche's database from when the car was manufactured. And a VIN report generated from PPN area will show the serial numbers currently in the car. When you replace one or more modules you must change them using PIWIS and PPN login.

The battery was "locked" because of the failure it had with the cell voltage dropping, it protects itself with some sort of "emergency mode", and even after you have corrected the fault, you must go through a PIWIS procedure to "re-activate the HV battery" (this does not require PPN login).

ct14

We were living life at the limit with what little PPE and measures we had in place for this "dangerous" repair LOL. However I advice everyone else not to follow our path, because while unlikely bad things can happen.

PS: I have seen badly wrecked Taycans, where the battery suffered massive damage and not a hint of fire/sparking etc,... These batteries are built very safely.

Also, this is from Porsche official workshop manual training media:



Barehands

ct14

@mchrono Here is a screenshot of the battery modules section of a random PPN VIN report I printed for one of my Taycan customers.