22KW OBC FAILURE INSIGHT & POSSIBLE SOLUTION

[F1Ruaraidh]

Hello all, i have the same issue- overal question about the mosfets- do they have too low a power rating?

It's a 32A charger. You cannot fit 32A silicon. Thermal derate of the devices alone will mean they are operating at or beyond their limits as soon as they warm up!

Should be 40 or 60A minimum. It's a question of what's available in the same form/fit/function package so it can be retrofitted.

That might not be possible.

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[whitex]

It''s never that simple.

Porsche will have specified the requirements. That will have included sign off and acceptance specs. This is a Tier 1 part.

Porsche is ultimately responsible for
1) not defining the test cases correctly
2) not thinking about single phase use on a three phase charger
3) not specifying the overload spec (defines the silicon rating)
4) not properly defining durability and thermal testing (to properly define how the silicon derates at temperature)

All of the issues are knowable, should have been found in any self-respecting DVP&R plan and fixed long before production.

Porsche made a great car but their hubris made a terrible EV.

J1.1 should have been the D sample validation prototype and J1.2 the launch vehicle.

Don't even get me started on the stupidity of the 150kW DCDC converter (derated to 105 in my case due to yellow ring of death at 60% SoC....)

You might be right that Porsche screwed up the product definition, but that would contradict the statement I was initially replying to (below).

When the OBC fails and Porsche repairs it for you for free, Porsche then claims this cost back from Metasystems. Every single time.

 

[F1Ruaraidh]

It very much depends on the supply contract between Porsche and Metasystems.

They are all different. For a small company to bear ALL warranty cost including all the labour at dealers globally (quite out of their control) would be insane.

I don't know of ANY Tier one that would accept that level of warranty risk. I sure as hell wouldn't and have done global engine supply contracts to major OEMs for high performance vehicles.

There is a reason for the tiering system.....

 

[whitex]

Quick update. It seems I spoke too soon. While my symptoms were identical to when OBC died, I did some further investigation and it looks like my OBC is still functional, just not with its usual EVSE (the one which it has been charging from for over 2 years now, previously serving other EVs). Not sure what is causing the issue, as the EVSE is not throwing any errors, but the Taycan will not charge from it. Tried another EV (Audi) on that same EVSE, it appears to engage the relay but only for a short time, then shuts it off - end result it's not charging. Not a lot of time over next couple of weeks to debug in depth, will use a portable EVSE for now.

Old post, but I just realized I never updated on it. The problem ended up being embarrassingly simple. There were small pieces of dried leafs stuck in the J1772 plug, most likely got there because a wet leaf got blown over the charge port during plugging it in, then got shredded and pushed in the plug when the plug was plugged in. Blowing it off with compressed air fixed the problem. Nothing like this has happened to me before or since, but I will know for the next time, first thing to check is look for any foreign matter in the plug or the charge port.

 

[F1Ruaraidh]

Oooh lucky find!

 

[whitex]

It very much depends on the supply contract between Porsche and Metasystems.

They are all different. For a small company to bear ALL warranty cost including all the labour at dealers globally (quite out of their control) would be insane.

I don't know of ANY Tier one that would accept that level of warranty risk. I sure as hell wouldn't and have done global engine supply contracts to major OEMs for high performance vehicles.

There is a reason for the tiering system.....

I suspect you are right. This gets even trickier for software products (should the cost of updating software by the dealers be billed to the software provider for each bug fund and a fix released?).

It is still hard to imagine how between Porsche and Metasystems, over 7 years, they haven't worked out a solution better than "let's just discontinue the part and tell the customers that they didn't need it anyways".

 

[F1Ruaraidh]

I suspect you are right. This gets even trickier for software products (should the cost of updating software by the dealers be billed to the software provider for each bug fund and a fix released?).

It is still hard to imagine how between Porsche and Metasystems, over 7 years, they haven't worked out a solution better than "let's just discontinue the part and tell the customers that they didn't need it anyways".

It's probably because as I said above, a higher capacity part doesn't fit the existing package so the a wholesale re-design is needed.

 

[whitex]

It's probably because as I said above, a higher capacity part doesn't fit the existing package so the a wholesale re-design is needed.

There is physical room inside the charger. Sure, they may have to respin the PCB for a proper fix, which may include higher rated power mosfets, or perhaps some other change since we know those parts have failed even when people were charging well below the rated 32A. It's not a super complex PCB like a PC motherboard with length and impedance matched data buses running at super high speeds.

PS> I am still somewhat confused how the 32A rated mosfets relate to the 80A charging current in North America (for those who have the 19.2kW/22kW upgraded parts).

PS2> We have an Audi Q8 eTron at home too, which also has a 19.2kW OBC, but I haven't seen or heard anyone complaining about those failing, or see any recalls on those, or extended warranty (got a letter from Porsche that they are extending the warranty on OBC to 5 years, no such letter for the Audi). It's a 400V battery, not 800V, but on the AC side it draws 80A at 240V. I wonder what is different. Physically the charger looks to be the same form factor, though I haven't measured it exactly.

 

[F1Ruaraidh]

Exactly, these things are normally pretty reliable.

Chargers aren't always as simple as you might think! Lots of things (especially harmonics!) can kill them.

It all smacks of (like the ridiculous burning battery to precondition when hooked to shore power glitch) of insufficient (or more likely incorrect) validation.

 

[whitex]

Exactly, these things are normally pretty reliable.

Chargers aren't always as simple as you might think! Lots of things (especially harmonics!) can kill them.

It all smacks of (like the ridiculous burning battery to precondition when hooked to shore power glitch) of insufficient (or more likely incorrect) validation.

That's why I said it's probably not just the rating of the mosfet.

But you'd think between Porsche and MetaSystems, 7 years would be enough to root cause and redesign? Especially if they have in the past designed reliable chargers. Heck, 7 years is more than enough to work with another tier 1 supplier who has designed 800V chargers already in the field which have a good reliability record.

 

[prj]

2) not thinking about single phase use on a three phase charger

This one has nothing to do with it, in EU all the 11kW and 22kW charging stations are three phase and that doesn't stop the OBC's from blowing up.

I have 2x11 kW chargers at my house, I never charged with 22kW, and it also did not stop it from blowing up.

 

[F1Ruaraidh]

This one has nothing to do with it, in EU all the 11kW and 22kW charging stations are three phase and that doesn't stop the OBC's from blowing up.

I have 2x11 kW chargers at my house, I never charged with 22kW, and it also did not stop it from blowing up.

Yes I know. I'm in the EU.

The point is they fail EVEN ON SINGLE PHASE. There are huge failure mode areas that have simply not been validated.

They blow up even when never connected to three phase.

And of course they absolutely blow up on three phase too. My 11kW has done just the same

The fact they definitely blow up at lower power levels implies something more complex such as control issues or harmonics going on.

We're agreeing with one another here.

 

[chun]

Do you think Porsche does this with every part supplier

Well... they did it with LG also, so would you be shocked? Probably VW decision.

Every other manufacturer sued LG and got them to do full battery replacements for their cars on LGs dime, but VW/Porsche chose not to do that... because they are good guys, or maybe they just sign the worst contracts

They do module replacement, on their own dime. The modules with defect cells get repaired and used for chargers local storage. They pay out of their pocket for the service time, and in switzerland it's 600 an hour.

For sure they have some shit contract, where they voided LG of responsability since it wasn't LG assembling the modules.

There's also 3rd party repairing shops saying how shit the battery assembly is, with single use bolts that need to be replaced if opened, with 0 pressure and temp of the battery coolant sensors, with poor current leak monitoring and all sort of crap. So probably LG could just blame all of this shit for the cells going bad in court, and porsche would never win, unlike all the other brands that sued LG.


Would you really be shocked if the situation is the same with the 22kw obc?

 

[F1Ruaraidh]

Well... they did it with LG also, so would you be shocked? Probably VW decision.

Every other manufacturer sued LG and got them to do full battery replacements for their cars on LGs dime, but VW/Porsche chose not to do that... because they are good guys, or maybe they just sign the worst contracts

They do module replacement, on their own dime. The modules with defect cells get repaired and used for chargers local storage. They pay out of their pocket for the service time, and in switzerland it's 600 an hour.

For sure they have some shit contract, where they voided LG of responsability since it wasn't LG assembling the modules.

There's also 3rd party repairing shops saying how shit the battery assembly is, with single use bolts that need to be replaced if opened, with 0 pressure and temp of the battery coolant sensors, with poor current leak monitoring and all sort of crap. So probably LG could just blame all of this shit for the cells going bad in court, and porsche would never win, unlike all the other brands that sued LG.


Would you really be shocked if the situation is the same with the 22kw obc?

These things are generally defined by corporate boiler plate. Since the platform was shared with Audi, I highly doubt Porsche got their own way here.

Mind you, my recent experience with Porsche HVAC flap actuators (internet shows this is a problem going back 25 years or more) shows that Porsche can make their own kind of special incompetence all by themselves....

 

[ct14garage]

How is that Porsche's problem? It should force MetaSystems to redesign so it's reliable if they don't want to go bankrupt, no? They've had 7 years already.

Because Meta System is no more, they have already gone bankrupt and dont exist anymore. Therefore Porsche can only discontinue the 22KW OBC as the company making it is dead and wont make them anymore!

The company applied for bankrupcy at the Italian court 2 years ago and as of today stands liquidated!

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