2025 Taycans - fiberglass composite underbody guard?

[kele]

Hi! Browsing through the forum I came across somebody saying that the 2025 model have a change to the underbody - instead of the steal panel, they have a fiberglass composite guard. Allegedly this should prevent the problem with a small dent leading to a costly battery replacement.

Does anyone know more about this? It would be a pretty strong argument to buy 2025 over 2024.

In this review they mention this change for the performance plus battery https://www.caranddriver.com/reviews/a60360621/2025-porsche-taycan-drive/

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[chun]

It won't prevent damage to the underbody components (battery) any more than the steel one.

It has a different impact profile. Likely it shatters instead of bending, on certain impacts, lowering the chance of it putting excessive pressure inwards on heating pipes and battery components. On most impacts it should behave very similar to the steel plate, albeit a tad bit stronger.

But if we're assuming you still need to replace the whole tray, not just the under-body guard, like on old models, it could still be just as pricey.

There's also the component of driving with it damaged. Say you hit something, it shatters in some place, and now water can get in. How bad would the damage from that be?

Fiberglass composites generally outperform iron sheets in terms of tensile strength, particularly when considering the weight ratio; but it being on the underside of a car, there can be all kinds of impacts and all kinds of directions. Sooooo who knows?

We simply don't know. Only Porsche does.

You can send them an email i guess...

 

[f1eng]

On most impacts it should behave very similar to the steel plate, albeit a tad bit stronger.

Glass fibre is nowhere near as strong or stiff as steel.

 

[chun]

Glass fibre is nowhere near as strong or stiff as steel.

We are talking about fiberglass composite.

In case it wasn't very clear.

It is stronger than steel against mechanical force / impacts, with a slightly better impact profile. But it offers other qualities also, and it also has downsides, obviously.

fiberglass composite:

• Resilient and flexible: Fiberglass composite panels can withstand large deflections associated with normal load and impact conditions without suffering damage. They return to their original shape when the loading is removed.
• High impact resistance: Fiberglass composite materials are designed to absorb energy and dissipate impact forces, making them suitable for applications where shock and vibration are present.
• Low risk of cracking: Fiberglass composite’s flexibility and ability to absorb impact reduce the likelihood of cracking or shattering, unlike brittle materials like iron sheet.
• Weight advantage: Fiberglass composite is significantly lighter than iron sheet, making it an attractive option for applications where weight reduction is crucial.

In all kind of impacts, besides impacts against sharp objects, it should be superior to the steel panel. Albeit, not by much, but superior.

Nothing beats titanium, but fiberglass composite will be superior to the old underbody in 90% of cases.

It is quite obvious that they were more worried about dents putting pressure on internal components rather than the underbody being straight penetrated by something. It is obviously a compromise, cheaper than titanium and better than steel, which in the future might lead to further recalls, if by any chance a freak accident happens where something penetrates it.

 

[Boss Hogg]

There's also the component of driving with it damaged. Say you hit something, it shatters in some place, and now water can get in. How bad would the damage from that be?

It has holes in it, without the small rubber parts the J1 had, so water is going to get in there.

 

[chun]

Just no.
Only in weight savings.
Unless it's carbon/kevlar composite but it's not.

Science disagrees, but ok.
Just so we're clear, we are talking about mechanical impacts, but that does not include bullets being shot at it, for the american forum users In case that is from where your comparison to kevlar is coming from.

 

[chun]

It has holes in it, without the small rubber parts the J1 had, so water is going to get in there.

Are you talking about the drainage holes? Yes, those are still present, but they don't lead directly to any of the electrical bits or HVAC conduits. Otherwise what holes exactly are you talking about?

The rubber bits on the drainage holes are not really so water doesn't go in there, it's so bugs or other sort of road sh*t doesn't get in there, and i'm quite sure I read that porsche started advising dealers to remove those upon delivery of cars, so either way not relevant

 

[f1eng]

We are talking about fiberglass composite.

In case it wasn't very clear.

It is stronger than steel against mechanical force / impacts, with a slightly better impact profile. But it offers other qualities also, and it also has downsides, obviously.

fiberglass composite:

• Resilient and flexible: Fiberglass composite panels can withstand large deflections associated with normal load and impact conditions without suffering damage. They return to their original shape when the loading is removed.
• High impact resistance: Fiberglass composite materials are designed to absorb energy and dissipate impact forces, making them suitable for applications where shock and vibration are present.
• Low risk of cracking: Fiberglass composite’s flexibility and ability to absorb impact reduce the likelihood of cracking or shattering, unlike brittle materials like iron sheet.
• Weight advantage: Fiberglass composite is significantly lighter than iron sheet, making it an attractive option for applications where weight reduction is crucial.

In all kind of impacts, besides impacts against sharp objects, it should be superior to the steel panel. Albeit, not by much, but superior.

Nothing beats titanium, but fiberglass composite will be superior to the old underbody in 90% of cases.

It is quite obvious that they were more worried about dents putting pressure on internal components rather than the underbody being straight penetrated by something. It is obviously a compromise, cheaper than titanium and better than steel, which in the future might lead to further recalls, if by any chance a freak accident happens where something penetrates it.

Pretty well everything you write here is wrong.

I was one of the pioneers of the use of composite materials in Formula 1 over 40 years ago and have considerable experience of the use of different fibres and resins as well as most engineering alloys.

Glass fibre is nice and cheap and flexible, that is about it.
If the bottom of the battery takes a vertical impact the fibreglass won't protect anywhere near as well as aluminium but also will not show it since after considerable deflection it will spring back and any damage to the cooling will not be seen from outside.

 

[VONRichie]

The article says “ The optional pack, still called Performance Battery Plus, grows from 83.7 to 97.0 kilowatt-hours. And the underbody protection for the pack switches from aluminum to a composite to shed 22 pounds.”

Doesn’t specify what composite……

 

[kele]

It won't prevent damage to the underbody components (battery) any more than the steel one.

It has a different impact profile. Likely it shatters instead of bending, on certain impacts, lowering the chance of it putting excessive pressure inwards on heating pipes and battery components. On most impacts it should behave very similar to the steel plate, albeit a tad bit stronger.

But if we're assuming you still need to replace the whole tray, not just the under-body guard, like on old models, it could still be just as pricey.

There's also the component of driving with it damaged. Say you hit something, it shatters in some place, and now water can get in. How bad would the damage from that be?

Fiberglass composites generally outperform iron sheets in terms of tensile strength, particularly when considering the weight ratio; but it being on the underside of a car, there can be all kinds of impacts and all kinds of directions. Sooooo who knows?

We simply don't know. Only Porsche does.

You can send them an email i guess...

The article says “ The optional pack, still called Performance Battery Plus, grows from 83.7 to 97.0 kilowatt-hours. And the underbody protection for the pack switches from aluminum to a composite to shed 22 pounds.”

Doesn’t specify what composite……

Some people on this forum mentioned what it is in other threads. AFAIR fiberglass composite. Btw. I believe other EVs also started using fiberglass composites for protection and light weight.

 

[Scandinavian]

The article says “ The optional pack, still called Performance Battery Plus, grows from 83.7 to 97.0 kilowatt-hours. And the underbody protection for the pack switches from aluminum to a composite to shed 22 pounds.”

Doesn’t specify what composite……

Protection from what???

Water splashes?
Water ingress?
Gravel impact?
Ground impact?

 

[kele]

Pretty well everything you write here is wrong.

I was one of the pioneers of the use of composite materials in Formula 1 over 40 years ago and have considerable experience of the use of different fibres and resins as well as most engineering alloys.

Glass fibre is nice and cheap and flexible, that is about it.
If the bottom of the battery takes a vertical impact the fibreglass won't protect anywhere near as well as aluminium but also will not show it since after considerable deflection it will spring back and any damage to the cooling will not be seen from outside.

Thanks for sharing! Personally, I’m less worried about some radical cases of underbody penetration and more worried about a random rock hitting the bottom of the car, causing a small dent and then going through the ordeal that some people on this forum had to recently go through. Based on what you are saying and my pedestrian understanding of physics - composite fiber glass have a chance of performing better in these cases, right? Wouldn’t the relative elasticity of material absorb and distribute the energy from the rock and cause a shallower vector of impact leading towards the battery?

I imagine that this is what Porsche and other ev companies may be going after. It’s not going to be as good as titanium in case of a penetration, but better than steel for these minor cases that end up with disproportional damage.

And of course shedding the weight is nice too.

Does that argumentation holds water?

 

[f1eng]

Thanks for sharing! Personally, I’m less worried about some radical cases of underbody penetration and more worried about a random rock hitting the bottom of the car, causing a small dent and then going through the ordeal that some people on this forum had to recently go through. Based on what you are saying and my pedestrian understanding of physics - composite fiber glass have a chance of performing better in these cases, right? Wouldn’t the relative elasticity of material absorb and distribute the energy from the rock and cause a shallower vector of impact leading towards the battery?

I imagine that this is what Porsche and other ev companies may be going after. It’s not going to be as good as titanium in case of a penetration, but better than steel for these minor cases that end up with disproportional damage.

And of course shedding the weight is nice too.

Does that argumentation holds water?

A bouncing rock is a bit indeterminate but fibreglass will absorb less energy than metals on impact but probably not have permanent deflection.
Titanium is nothing special really, it has half the density but also half the stiffness of steel. Aluminium has a third the density of steel so is lighter than titanium but also a third the stiffness, most engineering metals have the same specific stiffness, Beryllium and Boron are outliers but expensive and difficult to use.

With composites it depends strongly both on which fibres and which resins are chosen how strong, stiff and resistant a composite part is. Fibreglass has the lowest properties, including price.

It is unlikely to get a dent, more likely a split or hole. Whether it will cause the ridiculous situation you allude to - maybe.

 

[VONRichie]

Now I’m now saying car manufacturers always get it right….
Buy surely us mere mortals just have to trust that Porsche know what they are doing….

And it’s lighter so we go faster

 

[Bennachie]

Is j1 'protector' not steel rather than ally?

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