Anyone with PIWIS?

[howardmw]

No, just a Cayenne with an AGM. But it works fine to maintain voltage on the Taycan.

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[questionmillennium]

No, just a Cayenne with an AGM. But it works fine to maintain voltage on the Taycan.

My only concern would be sudden voltage drops or dips. I’m looking to do ALK and Matrix headlights and I heard those can take a long time to complete

 

[howardmw]

I'm no electrical engineer, but I think you just want to prevent battery drain from letting your Taycan 12v drop too low from all of the accessory usage, and a running engine with jumpers will keep the Taycan battery voltage up while hooked up to PIWIS.

 

[questionmillennium]

I'm no electrical engineer, but I think you just want to prevent battery drain from letting your Taycan 12v drop too low from all of the accessory usage, and a running engine with jumpers will keep the Taycan battery voltage up while hooked up to PIWIS.

I agree 100%. I’m no expert, so I asked Gemini about this very thing a few days ago and it strongly advised against it. What have you done with you car via PIWIS so far? How long did it take to complete the tasks?

 

[howardmw]

That's funny, because it was Gemini who originally recommended the jumper cables. I did the LED matrix upgrade on my car. It took me all day, but mainly because I was ultra cautious in navigating PIWIS for the first time. If I were to do it again, it would probably take about an hour.

 

[jakeCT]

What do you guys use as a maintainer to keep the voltage within the 13 - 14V range?

Battery maintainers would not be the right tool for this as it would not have enough output to prevent a voltage drop.

There are DIY solutions that use a PC power supply but the best off-the-shelf product I found for this and trusted by many PIWIS coders (mainly on Rennlist) is this: Schumacher Electric DSR Pro

I have a CTEK Lithium maintainer but also bought and use the Schumacher for coding.

On the Taycan it’s possible to do coding without a battery power supply, unlike other Porsche ICEs, however when auto-coding some modules the 12V gets drained and interrupts the process and you run the risk of bricking expensive components.

 

[mystermykee]

I like to live dangerously and hook up to nothing.

 

[howardmw]

I like to live dangerously and hook up to nothing.

Let's hope those words don't wind up on a gravestone for your Taycan!

 

[questionmillennium]

I like to live dangerously and hook up to nothing.

I have done this in the past not thinking about the dangers of the 12v. I did this for egress warning, 3D parking vision, and cross traffic alert. I don’t feel comfortable doing the same thing when autocoding multiple modules

 

[howardmw]

I believe its a question of how long you are working with just 12v power on the car and running the computers. The longer you work, the higher the risk of your battery dropping below the level where everything powers off. If it powers off in the middle of recoding, that is when you get a brick and a $3000 bill from Porsche. If I were coding all of the time, I would buy a power supply, but for just the one time shot doing the matrix, using the "donor car with jumper cables" method was fine. I ended up idling the Cayenne for quite a while, but dont think that causes any harm.

Good luck with your project!

 

[whitex]

I believe its a question of how long you are working with just 12v power on the car and running the computers.

While PIWIS is connected, HV battery is active, as is the DC2DC converter, why would the 12V battery run down given it's essentially always being charged (barring perhaps recoding around the DC2DC converter)? DC2DC converter is like an alternator in ICE cars.

 

[howardmw]

While PIWIS is connected, HV battery is active, as is the DC2DC converter, why would the 12V battery run down given it's essentially always being charged (barring perhaps recoding around the DC2DC converter)? DC2DC converter is like an alternator in ICE cars.

I had read that when the car is in service mode, the HV battery is disconnected for safety, which is why the power supply is required. Here is where I read that:

https://www.taycanforum.com/forum/t...adlight-activation-for-us-taycan.33201/page-6

 

[mystermykee]

Let's hope those words don't wind up on a gravestone for your Taycan!

Indeed. But to anyone who is afraid to bricking their car during auto coding, don't be. In most cases, you can bring it back yourself. Dealer intervention is required if your gateway shits the bed, which fortunately is rare for a 12v drop alone.

 

[mystermykee]

I had read that when the car is in service mode, the HV battery is disconnected for safety, which is why the power supply is required. Here is where I read that:

https://www.taycanforum.com/forum/t...adlight-activation-for-us-taycan.33201/page-6

Partially true, but that's not what happens during a PIWIS session. Try for yourself. Turn car on, turn on headlights, blast the A/C, connect PIWIS, and walk away. Come back in 20min to find your car still on and working. How long would your 12v last if the HV battery actually disconnected. When you connect PIWIS, what is the red message you see on the dial? "high-voltage system enabled."

 

[mystermykee]

I have done this in the past not thinking about the dangers of the 12v. I did this for egress warning, 3D parking vision, and cross traffic alert. I don’t feel comfortable doing the same thing when autocoding multiple modules

Understandable. Not all modules and not all auto coding will cut 12v bus from HV battery. As a precaution, I turn headlights, radio, and HVAC off.

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