no3rdseat - follow the original link and read through the comments. Apparently there is confusion over the power the battery makes, if it could be a typo, and what the power rating means in the first place -
Dave G Says:
October 11th, 2007 at 8:05 pm Quote
Don’t think of taking the 600 watt/hours and trying to scale it up for the Volt. It’s a completely different type of battery.
Here is a snippet from Denise Gray (GM’s battery Guru) from her recent testimony before the U.S. government.
There are really two types of batteries that we require. The one most people are familiar with is called “charge depletion.” Think of this as a flashlight battery that depletes it energy with use, and then is either disposed of or recharged. It is the rechargeable version of this battery that we are interested in for plug-in hybrids. This is a new area of focus for USABC.
In addition to charge depletion, there is another type of battery known as “charge sustaining.” These batteries are designed to accept and delivery power while maintaining a constant state of charge – they never deplete. These charge sustaining batteries are in use in hybrid vehicles on the road today, such as our Chevy Malibu and Saturn Aura hybrids. They store up the high power energy captured during braking and reapply that energy to help the vehicle accelerate.
Full testimony here:
http://democrats.science.house.gov/Media/File/Commdocs/hearings/2007/energy/03oct/gray_testimony.pdf
The EnerDel battery being discussed here is the charge sustaining type for HEVs. These batteries are constantly charging / discharging, so the chemistry trades less storage (watt hours) in favor of more charge/discharge cycles.
All charge sustaining batteries to date have been NiMH. The fact that EnerDel is releasing a cost competitive Li/Ion battery of this type is very significant.
B Says:
October 12th, 2007 at 4:19 pm Quote
Right their website refers to size and volume for same amount of kWh but as their technology is much more powerful (around 5 kW/kg) they can achieve equivalent performances with only 600 Wh instead of 1.6 kWh for NiMH prius pack, battery operates in charge sustaining mode so power density is more important than energy density (1 kW/kg for NiMH). In this sense they can provide a cost-competitive solution relatively to NiMH.
But at 800 USD and less for powerful Li-Ion you can achieve an even much more cost-competitive solution ….
If Enerdel is able to produce at 500 USD/kg as quote in interview that’s a huge advance but at 2500 USD/kg due to progress of Li-Ion that’s vaporware.
Forget 100 Wh/kg for LTO/Mn battery but 70+ Wh/kg due to very long life is already great … if price is competitive.
Don-
It’s all a matter of how fast the battery can discharge the energy it holds - regardless of how much is actually in there. To use a hydraulic analogy, a big NiMH is like a large jug of water with a leaky, drippy spout. A high power lithium ion “jug” of the same size is going have its tap fully open. An ultracapacitor is going to be like tipping the whole jug over!
If you want some numbers, the Prius’ pack can produce about 375 Watts per kilogram. NiMH chemistry has a theoretical maximum of about 1000W/kg. The A123 power tool cells produce well over 3000W/kg! As for EnerDel, we’ll just have to wait and find out.
So the more powerful the cell, the less of them you have to have to produce the desired amount of power assist.
Li-ion is to lead-acid what fuel injection is to the carbuerator. Li-ion blows lead acid away.