chuckbdc

The latest PCA e-Brake News has an interesting piece, with a road test, of a hybrid system mod for the 991. An additional 175 HP on demand with a system that they say adds 180 lbs.

The website is http://vonnen.com

Works now and gives a hint of what's to come.

Oh and its just $75k!

Freddie Two Bs

Someone must have thought "the 991 was too nice a 911, we need to find a way to make it at least a bit ****ty".

jnolan

Sharm

Dammit Chuckbdc you beat me to it!

spdracerut

I did an analysis of their system and it doesn't make sense. Basically, the battery pack is way undersized for the current draw they are asking from it. Batteries have what is known as a C-rate. Basically how fast you charge/discharge a cell. C-rate normalizes for battery capacity. Long story short, the higher the C-rate you charge/discharge a battery cell, the quicker you shorten its life.

So say you have a battery with 5Ah capacity. If you charge/discharge it at 5A, that's a C-rate of 1. Discharge at 10A, that's a C-rate of 2. Discharge at 2.5A, that's a C-rate of 0.5. For reference, a Model S at max acceleration has a C-rate of ~5. Because this battery Vonnen is using is so small capacity, it will have a C-rate of about 130... Typically for good cell life, you typically don't want to exceed 0.5C-1.0C too much.

Battery can't be li-ion. No way it could handle a C-rate of 130. Most of the time, you try not to exceed 1C. So.... I can't imagine it handling 130x that. So MAYBE LiPo battery like those used in R/C planes. But even those, I've only found a max C-rate of 60 with 20-30 being common. So.... Vonnen is asking 2x more C-rate than anything I can find.

visitador

Interesting idea about getting instant torque. Asides from the technical concerns, a $75K charge will mean that I would have shed around $150K (my 991.1 was CPO). At that price point, I may as well get a slightly used 991.1 GT3, maybe even a 991.2 GT3 if the economy falls apart.

Drifting

2000se

Good stuff spdracerut. This is the kind of information that helps people understand the backdrop of things. Thanks for the enlightenment.

Sharm

In addition, why not just wait for the 992 hybrid which will be out in a couple years. For +$75k and a trade-in or sell off of your 991.1, you'll easily be able to buy one from the factory directly from Porsche.

Btw, added linked youtube video below.

chuckbdc

For some slower is better. To each their own.

WCE

Very cool setup - if I still had my Carrera this would be tempting (at a price point under $20k).
$75k will be a very tough sell... maybe they could get that for their stage 2 (350hp) kit?
Battery is lithium titanate - will that give them their C-rate spdracerut? (excerpt from Wikipedia):

A lithium-titanate battery is a modified lithium-ion battery that uses lithium-titanate nanocrystals, instead of carbon, on the surface of its anode. This gives the anode a surface area of about 100 square meters per gram, compared with 3 square meters per gram for carbon, allowing electrons to enter and leave the anode quickly. This makes fast recharging possible and provides high currents when needed.[7] Lithium-titanate cells also last for 3000 to 7000 charge cycles, far longer than other battery chemistries.[8]

A disadvantage of lithium-titanate batteries is that they have a lower inherent voltage (2.4 V), which leads to a lower specific energy (about 30–110 Wh/kg[1]) than conventional lithium-ion battery technologies, which have an inherent voltage of 3.7 V.[9]

Lithium-titanate batteries are reported to have an energy density of up to 177 Wh/L.

Stevelev

X2 ! (for my 981). I cant imagine many will rationalize $75k for this but time will tell.

garfunkle

This is one of those mods that I like reading about and am glad other people are doing because it is very interesting but I am not a customer.

I've been following these guys for a couple of years now and some of my observations and un educated opinions.

1. Needs more capacity. This system[battery] dies after WOT for >10 seconds. So maybe double up on batteries but then weight + charging capacity.
2. ~120 pounds of added weight is good. Makes it still lighter than a 991.2 :0
3. That INSTANT torque would likely ruin me for other cars
4. The price point is a little rich but it does include labor and taking apart the transmission
5a. This should have been done on a 996 IMO since they are so cheap
5b. As soon a V.2 comes out or battery technology gets even a little better, a car with this kit will have the value of a paper weight.

spdracerut

Hmm.... well, if we assume that C-rate is a function of anode surface area, the lithium-titanate chemistry has about 30x higher C-rate capability than a standard li-ion. So li-titanate might be comfy with a C-rate of 30. As Tesla uses a C-rate of about 5x the comfy limit for li-ion at max acceleration, then maybe we can assume the li-titante can do 150 which would be enough for this application which is asking 130. But man.... that's a lot of assuming. One would hope they did cell life testing. Another thing to consider is the battery will get very hot when they do this max 130C rate. It's a lot of current to pull out of a very small battery, so there's not much mass to spread out the heat essentially. Think small tea cup of water on the stove vs. a huge put of water. So their battery cooling scheme better work well.

Carlo_Carrera