There are several battery chemistries and construction strategies in this Li group. So far only A123 Systems LiFePO4 is proven safe to use in hostile environments. The techology was produced in the US, with key patents by A123 Systems, and significant research funded by US DOE. The Obama administration appears to support China purchasing A123 assets in Jan 2013, which is a huge mistake. China firms had been widely counterfiting LiFePO4 batteries, which had impacted A123 Systems significantly. China is picking up the patents and other assets for cheap, leaving US EV and EV hybrid makers without an economic safety net in battery techology. A vocal response might stop the final gov approvals.
LiFePO4 batteries do not produce a free oxygen at raised temps, and have very low internal resistance so they do not warm up with high currents like other Li-Ion or Li-Poly batteries. They can also be crushed, shorted, and do not just explode or create O2 driven fires as the other batteries do.
There is a lot published about Li-Ion and Li-Poly fires. Google is your friend here. There is a lot of field data from the RC Airplane and car industry about failures leading to explosions and fire. There is also a lot of field data from explosions and fire in the Phone, Notebook computer, and other portable devices.
A lot of people believe that failures can be controlled with good battery management. What we do know is that metal crystal growth thru the separator, will sooner or later cause a short and fire, for a significant number of batteries already deployed.
While this "risk" is managable on a small scale, it becomes frightening on a large scale. Especially when failures with fires can be caused fairly reliably ... like overcharging without a reliable external thermal shutdown.
So as the power supply cap's in your embedded design degrade, and the microprocessor is no longer stable ... is it safe to let software sample charge voltages and temps, and be responsible for turning of the charge enable MOSFET? .... I don't think so.
mrdon, it's more like thank god we have dedicated logic solutions available, and active software control is not always required.
The problem is, that too many designs have programmable software controls that if compromised can override safety limits in various ways ... either forcing overcharging, or forcing excessive discharge currents leading to overheating and failure.
Since most rechargable systems are plugged in over night, that invites syncronized night fires if the systems can be hacked.
For a well funded non-state actor, with long term goals, there are non-obvious ways to introduce compromized firmware, without network access.
Consider a non-state actor funding/purchasing a major code reader company, or major automotive diagnostic system company, and then spending several years undercutting the competitors for a system specifically targeting EV and EV hybrid models. With a firmware update that inserted the virus/trojan in the months prior to the planned attack, the service organizations using those tools could infect a significant percentage of vehicles, especially in areas that require emissions testing.
Consider a non-state actor purposefully placing software/hardware engineers into automotive and technology companies producing these active battery management systems, to inject the attack even on non-field programmage systems ... a different form of jihad.
NASA and major corporations can not keep asian spies out of their R&D offices ... it's doubtful that a well planned jihad attack would have problems placing good engineers into R&D teams.
The Boston attacks this week make it pretty clear, that we are blind to those wanting to attack western interests.
There are also some significant economic incentives to this class of attacks, as it will cause a predicable significant short term marktet crash. So the non-state actor may be strictly motivated by greed.
Charles, I really enjoyed the slideshow of the various lithium-ion battery designs. We have definitely come a long way from the carbon-zinc battery. There's a lot of embedded intelligence in these designs to regulate the batteries output voltage and current under various electrical loads. The last battery slide, I believe it was Bak, looks pretty radical. Again, thanks for taking us on this tour of lithium-ion battery technology. Again, great slides!!!
I think the safety side of your assertion is the most critical.
Consider that some day someone is going to decide these automobiles should be networked, and include a wifi connection or cell phone data connection in their design.
Then consider that some hacker acting in behalf of a non-state actor, decides to declare war by inserting a virus in automobiles firmware, to overheat the Li-Ion batteries at the 20th annivesry of the 9/11 attacks, causing concurrent massive fires on streets, on hiways, in parking structures, in home garages in most western countries. We then have battery fires, cascading into accidents for moving traffic, compounded by accidents and structure fires beyond our public safety services ability to respond.
Consider what happens if this same non-state actor targeted cell phones and portable computers with Li-Ion batteries at the same time.
Li-Ion batteries are bombs, with microprocessor controlled triggers.
There's a great deal of hope surrounding Envia's battery, AnandY. Admittedly, the battery business has a reputation for making big promises and not delivering, but this one has been promising enough to draw support from GM.
A middle school team from Rochester, Mich., has again nabbed the grand prize in the annual international Future City Competition, which drew students from 37 regions of the United States, as well as from England and China.
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