An article was recently published in the Sacramento Bee discussing plug-in hybrids. The story emphasized the development of the AFS Trinity which is a plug-in Saturn VUE conversion using lithium-ion batteries and ultracaps which has a 40 mile EV range and range extender.
In a provocative assertion, the author references a UC Davis study noting:
“The 300-pound battery pack General Motors is building into its Chevrolet Volt plug-in, for instance, can’t yet deliver its promised 40-mile range and the long-term durability needed for a mass-market car, according to a report by a hybrid technology research team at the University of California, Davis.”
The article’s author, Jim Downing, was kind enough to give me the reference to which he refers. You can read its 29 pages of technical detail here.
The thrust of the report is to explain the current state of hybrid car batteries, looking at li-ion and NiMh and comparing each, including the various cathode subtypes. They are measured against the required standards set for by among other authorities, the USABC, a government group including representatives from the major US auto makers.
The USABC battery requirements are set forth for a mass-produced PHEV-40 or Volt:
1. Power density of 380 W/kg
2. Energy density 140 Wh/kg (EPRI gives 60 Wh/kg, MIT 100)
3. Energy capacity 17 kwh
4. OEM cost $200/kwh
5. Deep Discharge Cycle 5000
Let’s look at some speculative values our friend Alex S. (AES) has determined for the Volt’s competitive battery-makers.
Energy density = 108 Wh/kg
Power density = >3000 W/kg
energy density = 95 Wh/kg
power density = 2000 W/kg
Of course these values for LG and A123 cells are speculative and we do know that new formulations from each supplier have been developed for the Volt project. Furthermore, the cost these companies plan to charge GM for the batteries remains unknown. Most experts quote this presently at $800 – $1000 per kwh. So the price of the Volt then seems to depend in great part on how much GM will have to pay for its battery.
Should GM subsidize the battery-makers or should the battery-makers subsidize GM?
In the end it is fair to say that based on what we know publicly GMs suppliers lithium batteries do nearly meet or exceed meet the USABCs performance criteria, and exceed EPRIs requirements.
Of course all that really matters is that the batteries meet GMs own internal criteria, and the fact is, we already know the first running Volt prototype has met its 40 mile mark.
Source (Sacremento Bee)
This entry was posted on Sunday, May 25th, 2008 at 7:58 am and is filed under General, PHEV. You can follow any responses to this entry through the RSS 2.0 feed. Both comments and pings are currently closed.