Lithium Ion Battery Cost ???
08-20-2009, 11:52 AM
#16
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Tony from Voltphreaks here. Was refered to this thread. I think eventually, most high end race applications/cars will be using a lithium battery instead of a lead-acid battery. The weight savings can be very significant! Disadvantage of course is cost, though with time that will change.
Just want to mention, that the Voltphreaks battery features a low voltage cutoff, so that you will never be left with a stranded car with a dead battery. The battery that we recommend for most Porsche's is the VPR750, which weighs 5.25 pounds, and contains the low voltage cutoff feature. Before the battery is completely drained, it will automatically disconnect itself, leaving enough power to still start the car a couple of times (in case a sensor or computer is left on, etc).
- Tony
Just want to mention, that the Voltphreaks battery features a low voltage cutoff, so that you will never be left with a stranded car with a dead battery. The battery that we recommend for most Porsche's is the VPR750, which weighs 5.25 pounds, and contains the low voltage cutoff feature. Before the battery is completely drained, it will automatically disconnect itself, leaving enough power to still start the car a couple of times (in case a sensor or computer is left on, etc).
- Tony
Thanks!
08-20-2009, 09:51 PM
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- Tony
08-20-2009, 11:24 PM
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What particular specifications?
"Specmanship" and "power" have proven to very a very unreliable combination, as many OEMs will attest to (yes I am in the high reliability Power business). It all depends upon the design parameters versus actual use.
I would take a 5 year life with a "grain of salt', until I saw the the derating guidelines, MTBF calculations and related design assumptions.
What will the warranty cover and under what conditions... that's your "life" for worst case planning.
We know what the Porsche manual says about batteries and warranties, and I assume it will apply to the Lithium ion as well. Will Voltphreaks match it word for word, assuming the prices are comparable. I think $650 is as good a guess as any for the Porsche option, but before I have to make a decision I will find out and have our "techies" evaluate to the extent possible?
"Specmanship" and "power" have proven to very a very unreliable combination, as many OEMs will attest to (yes I am in the high reliability Power business). It all depends upon the design parameters versus actual use.
I would take a 5 year life with a "grain of salt', until I saw the the derating guidelines, MTBF calculations and related design assumptions.
What will the warranty cover and under what conditions... that's your "life" for worst case planning.
We know what the Porsche manual says about batteries and warranties, and I assume it will apply to the Lithium ion as well. Will Voltphreaks match it word for word, assuming the prices are comparable. I think $650 is as good a guess as any for the Porsche option, but before I have to make a decision I will find out and have our "techies" evaluate to the extent possible?
08-21-2009, 02:40 PM
#21
AT $650, I'd take one. At $2K, I'm not (quite) that silly ... and if someone is arguing a 3000lb street car needs to shed 20lb for $2000, I'm thinking I'll just take out the passenger seat for track days. Four bolts, ten minutes. And makes space to drive to the track with spares and tools ... : ) Also, go and get a $100 Jet Ski battery (which I use) ... maybe 5lb heavier than the Li batteries ... never fails me. Since the bloody GT3's love to kill batteries, I have a battery saver (it's just a voltage test between the battery and the positive post which isolates the battery below 13 volts ... I think it cost $40?) There are places in a car where you have to "throw money" to get results ... the battery box is not one of those places. : )
ps. I do applaud VoltPhreaks for delivering sensational products for racers, if I ever compete, I'll put it on my budget, no question.
ps. I do applaud VoltPhreaks for delivering sensational products for racers, if I ever compete, I'll put it on my budget, no question.
08-21-2009, 06:50 PM
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PCCB is $8k to save 50 lbs. Ok, it's unsprung, but still, eight thousand dollars??
The difference is that PCCB is hot technology, whereas a battery is not. Let's face it, a lot of this stuff makes a difference when tenths of a second matter in a race, but is simply ridiculous on a road car. Then again, GT3 ownership is about the heart, not the head.
The difference is that PCCB is hot technology, whereas a battery is not. Let's face it, a lot of this stuff makes a difference when tenths of a second matter in a race, but is simply ridiculous on a road car. Then again, GT3 ownership is about the heart, not the head.
08-21-2009, 08:19 PM
#23
PCCB is $8k to save 50 lbs. Ok, it's unsprung, but still, eight thousand dollars??
The difference is that PCCB is hot technology, whereas a battery is not. Let's face it, a lot of this stuff makes a difference when tenths of a second matter in a race, but is simply ridiculous on a road car. Then again, GT3 ownership is about the heart, not the head.
The difference is that PCCB is hot technology, whereas a battery is not. Let's face it, a lot of this stuff makes a difference when tenths of a second matter in a race, but is simply ridiculous on a road car. Then again, GT3 ownership is about the heart, not the head.
And the weight in the rotor is both unsprung and flywheel mass ... there's just no more valuable place to shave ounces, let alone pounds.
Speed costs money -- how fast do you want to go? I think $8K as an _UPGRADE_ is a nonsense price and Porsche is just making money while the sun shines. I used to think that PCCBs were too failure prone, then I thought they had "come of age" and were holding resale value, but now, I think they're just something guys that track at 8/10ths or 9/10ths will enjoy -- if I drove any harder and was risking offs (in a $132K RS?) then going into the kitty litter and finding I had two chipped rotors, well, that would sour me on the whole deal ... : )
08-21-2009, 08:40 PM
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The fact that it's rotational mass is not terribly important in this case because it's quite close to its spin axis. The big advantage is that it's unsprung, allowing the suspension to work better. Thus it is my opinion that PCCB is more a street upgrade than a track one.
08-21-2009, 08:59 PM
#25
It's my understanding that there is precious little difference in actual braking performance on the track between PCCB and iron. The main difference comes down to weight.
The fact that it's rotational mass is not terribly important in this case because it's quite close to its spin axis. The big advantage is that it's unsprung, allowing the suspension to work better. Thus it is my opinion that PCCB is more a street upgrade than a track one.
The fact that it's rotational mass is not terribly important in this case because it's quite close to its spin axis. The big advantage is that it's unsprung, allowing the suspension to work better. Thus it is my opinion that PCCB is more a street upgrade than a track one.
The rotors are not close to the center of the axis, they're the same shape (and nearly the same dimensions!) as the engine flywheel.
The unsprung mass is important on the street for ride quality, but the real measure is on the track where keeping the tire on the tarmac is the name of the game.
I think it makes a lot more sense to pay $8K for confident brakes on the track than for ride quality on the street. Either way, $8K on an already expensive 911 is hard to justify, especially when the car has such phenomenal steels.
08-21-2009, 09:03 PM
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I'm not a huge PCCB proponent, but I agree that the rotating mass is a huge issue with brake rotors (especially when they are 380mm in diameter).
08-21-2009, 11:10 PM
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08-21-2009, 11:35 PM
#29
I think you should email the mod to have your user nickname changed to "font of knowledge" ... but I the digression onto brakes was a "other wildly expensive parts that have intangible gains" discussion (just to beat that dead horse again...)
