After Gutenberg

Lithium ion batteries have been bandied about as a possible solution to the development of more efficient regular hybrids, plug-ins, or practical electric vehicles. Unfortunately such batteries have a greater likelihood to catch on fire or even explode.

Technology Review carried a story questioning whether lithium-ion batteries in electric cars posed a safety hazard. Someone dugg the story, sparking a furious debate.

The holymac was amidst the fray:

We’ve been using Li-Ion and Li-Poly cells in the University of Minnesota Solar Vehicle Project for years. We’ve ran several packs to the ground, over-stressed the batteries a lot, and we’ve never had a battery fire. I can really only recall one well built solar car that’s had a battery fire in the past few years, and that was because of an unfortunate short circuit.

When batteries are put on a larger device (like, say, a car), there’s more room for battery protection circuitry, and the batteries are actively cooled. Taking into account the already very, very low failure catastrophic failure rate found in laptop batteries, I’d say that Lithium-based batteries would be perfectly safe to put into cars.

Which prompted a somewhat contradictory observation from aveyuen :

@theholymac
As a member of the McMaster University Solar Car Project, I’ve seen two full out battery fires in solar cars (ETS, FSGP 2004; Northwestern, NASC 2005). I heard Stanford’s 2003 battery pack also went up in flames. Individual laptop batteries are seldom going to catch on fire… it’s when you get multiple batteries in parallel that you get the problems, which is why Li-ion batteries in electric vehicles for the mass market is a very different issue worthy of caution. Solar car people who design, build and trouble shoot their own battery protection circuits aren’t exactly representative of the average consumer.

And, as the say, the gauntlet was cast:

@aveyuen

I remember Northwestern in ’05, it was due to a short in a badly designed and poorly tested battery box. Their whole car in general looked like the design was rushed; if I recall they *barely* qualified. I don’t recall the Formula Sun fire in 2004… Stanford was the well engineered car that I was referring to. That was an unfortunate occurrence.

But my point is, considering how many solar cars have run over the years, and how few battery fires have occurred, Lithium-based batteries are pretty safe. It’s even more impressive when you remember the fact that the packs are not designed by professionals, and they’re run to the ragged edge of their performance by many teams. Basically, when you’ve got the space for the protection circuitry and the space for active cooling, Li-Ion batteries will take a pounding.

@theholymac
While I agree that Northwestern may not have been as experienced as they could have been while managing their pack, the cells they had I believe were known to take a beating (unlike the ones in ETS and Stanford’s 2003 car…. also our car). True, solar car teams are limited by weight and space, as well as somewhat inexperienced engineers (even for the good teams). But I think this is countered directly by the fact that solar car folks will do active maintenance on their battery packs, and can diagnose problems and fix them quite readily. My concern is that Joe Public has no idea whatsoever about how to maintain their battery pack, and this could result in either a) designing it so idiot proof that you essentially lose the gains you would get from switching from NiMH, or b) a lot of battery accidents (i’m thinking battery series mismatch would be first up). Either way the debate is still alive. For sure it’s a good technology and I’d love to see more research going into this, but we must always keep public safety in mind before we bring something to market.

P.S. Since you missed FSGP 2004′s accident, you missed a downright dramatic show. The car lit on fire right in front of the pits and the driver had to emergency egress.

This blog paid attention to the posturing not only because it is fun and educational to watch engineers fight, but also because solar cars, due to limitations of energy supply, are the epitome of electric hypercar design. Still, the debate about certain events and precipitating circumstances lost the larger context, which another observer stated well:

I think the point that everyone is missing here is that a Li-ion battery doesn’t often catch fire; a Li-ion battery PACK can very easily catch fire! A cooling system, sensors, and the almighty fuse aren’t going to do you any good when two leads *within* the battery pack short (often due to vibration). In many cases there’s nothing a fuse can do for that, as the current loop that is shorting is not through the main bus. Engineering a Li-ion laptop battery to give < 5A of current is easy, making a pack deliver 100 A continuous is the challenge that makes it dangerous. How many of you have actually seen an electric vehicle with a Li-ion battery pack? Tell me again that they're not dangerous once you've ran over to another solar car team with a bag of sand in hopes of putting out their battery pack after the thing has been burning for a solid 30 minutes (Formula Sun Grand Prix 2004). Or how about after you pass by the HazMat team as they clean up a burning electric car on the side of a highway (North American Solar Challenge 2005).

I'm not saying they shouldn't pursue Li-ion technology for cars; what i'm saying is that everyone that is accusing the authors of this article of 'fear-mongering' should probably realize that this is indeed a legitimate cause for concern, and at least up for debate. If they can make these packs idiot-proof then that's great - until then let's make sure that people aren't rushing them to market without fully safety-testing them.

And, another engineer adds a qualifying remark:

It’s important to understand that Li metal is not used in these cells. Li foil is highly reactive and will produce an exothermic reaction when exposed to moisture. I used to work in an Electrochemistry research group and have seen how a Li battery will explode. We were testing this by applying heat to a AA size Li cell and they will go off like a cherry bomb. Additionally, the electrolyte used in the cell is usually nasty stuff and will contribute to the explosion; however, pure Lithium foil is NOT used in the battery packs that are in laptops. Some companies do produce Li batteries but they are not sold as rechargeable batteries and they are not used in cell phones, etc. Cell phones and laptops use batteries that contain Li ions (hence the name) that are interpolated into a substrate. Li ion cells do have a high energy density and if there is a short in the cell, heat will be produced across the short and the plastic will melt around it. This story is BS and it shouldn’t be used to impugn a great technology by those who don’t understand the difference between Lithium and Lithium ion batteries.

Later elsewhere Joel Arellano made an observation, which, while promoting Austin-based Valence Technology and their modified product, U-Charge Power System, was nonetheless worthy of note since it informed AutoblogGreen readers that the chemistry of lithium ion batteries could be modified to lower the chances for fires.

Instead of using a cobalt oxide cathode found in most such batteries, Valence’s batteries use metal phosphate which doesn’t have the same tendency to burn when the battery gets hot. Unfortunately, such batteries only hold 75% of a charge compared to a regular battery. Engadget rightly points out that many drivers, especially in the U.S., may not be willing to lose efficiency in the name of safety.

At present, solar car ports, especially those with the newer photovoltaics demonstrating improved cost performance, scalability and durability are much more practical than solar panels on vehicles.

With public assurances being made that PLI / LiPo batteries, i.e., those that are unable to incur thermal runaway, are technically ready for use in electric vehicles, proponents are advocating the production, or, at the very least, large scale experimentation with plug-in hybrids. Even though VRLA (Valve Regulated Lead Acid) batteries provide less range, developers believe they are suitable.

Thus, a Californian, who commuted either to a train station with a solar car port or to an innovative company that fostered eco-commuting, could commute all electric one way, charge up on solar, and commute the other way all electric, provided, that is, such a plug-in hybrid was available for said commuter to use. An environmentally-friendly company could foster such an eco-commuting initiative with little initial cost. A further step then would be to make the power supply greener by means of co-generation, geothermal, solar, wind or other cleaner, cheaper energy.