crash safety

[1lesscar]

say I am whining down the road on my EPR and a car pulls out just as I get into the intersection. I try to avoid impact but the driver pulls out just as I pass. The EPR's batteries are smashed and in pieces. The car cathches fire. What do firemen and rescue worker need to know or do?

[Phantom]

I think the batteries would remain smashed in your example and not cause a fire.

Here is some data about li-ion batteries and fire supression/hazards:

http://www.nfpa.org/assets/files/pdf/research/rflithiumionbatterieshazard.pdf

Effectiveness of Suppressants
Fires involving lithium-ion cells are the result of electrolyte burning, which is a hydrocarbon/air
flame. Thus, many flame suppression agents will be effective in suppressing flaming
combustion. However due to the electrical nature of battery packs, particularly the high voltages
associated with large format battery packs, conductive suppression agents may not be a good
choice. In addition, because of the potential for re-ignition due to cascading cell thermal
runaway reactions, an ideal suppressing agent will stay suspended and prevent re-light of
1100034.000 A0F0 0711 CM0198
combustible mixture from cell hot surfaces. Suppressants shown to be effective include: inert
gas / smothering of flames170 (fire behavior testing data166 indicates that smothering is effective
in preventing flaming, but will not cool cells and prevent thermal runaway propagation), carbon
dioxide (Exponent typically uses carbon dioxide extinguishers to suppress flaming of cells
during testing – this will not cool cells and prevent thermal runaway propagation), water (a
number of sources170, 171, 172 have described the effectiveness of water to suppress flaming and
cool cells), and Halon.170, 172, 180

[Car Loss]

The first line of defense is a strong casing around the battery pack.  Many lithium types need this anyway, due to charge/discharge issues.  Like cars, the Empulse puts its pack inside the primary structure, which acts as a bumper.  I'm going to take a wild guess here: the actual battery cells themselves may weigh less than the housing, since the housing also appears to include stiffener plates inside.

There is talk in the EV business of a "master cutoff" switch somewhere, for the sake of mechanics, emergency responders, and salvagers alike.  Don't know where it would go or how it would look on an electric moto, but it would have to be someplace reasonably accessible and obvious, possibly standardized.  Yet it would also have to be safe from vandalism.  Thoughts?

Overall, however, I'm going to say that a box full of batteries is not significantly worse than the tank full of gasoline it replaces.  In all debates over alternative fuels and their pros/cons, people forget that gasoline wasn't gatorade in the first place.  In particular, an ullage space full of gas vapors is the definition of a bomb, which is why the military uses non-volatile fuels.  In this case, I think the issue is more of first responders being too used to thinking in petro terms, and having to remember the quirks of, say, gaseous fuels as well as electrics.  People would really rather just run with their assumptions, especially when put on the spot.

[protomech]

Good question. Chevy, Nissan etc publish first responder guides for dealing with their electric vehicles. I haven't seen anything like that from Zero or Brammo.

The first responder guides deal with two things: rescuing people from the vehicles (where to cut / where not to cut) and how to deal with a vehicle fire. #1 isn't an concern with a motorcycle, and #2 will probably just be clear the area and let it burn itself out.

The Empulse and ZF9 Zeros have approximately 30-50% of the stored energy capacity of a typical electric car which should mean the potential fire severity would be substantially lower. Since the battery is not enclosed in a somewhat air-tight cabin, any venting from a battery puncture / impact will be into the atmosphere and the explosion risk should be lower.

The Volt vehicle fires when tested by NHTSA were caused by coolant leaking onto several of the electronics boards following impact and vehicle rotation about the long axis. I suppose the Empulse could have a problem with a coolant leak .. weeks after impact and bike is totaled.

Also: the primary form of lithium in lithium ion batteries is not metallic lithium, it's lithium carbonate. Lithium carbonate is soluble in water, I don't think it has the kind of explosive reaction that metallic lithium does.

Edit: here's a video of Zero's Luke (liveforphysics) performing some percussive maintenance on the EIG cells in the 2012 Zero bikes. I would imagine the Brammo cells will be similarly safe. You can see some more videos of some rather intense fires resulting from cells being abused at the elmoto thread.

[2Slow4u]

Most likely nothing. If you did have a short circuit, pouch cells have a perforation in the tab material that will melt a break under short circuit condition.

Also, its important to note that the amount of electrical energy stored in the battery pack is only about 15% of the heat energy that will come from combustion. The packaging of the cells is what really burns. The SOC just determines at what rate it will burn, higher SOC will burn faster than lower SOC but the amount of energy (by mass) is the same.

Gas is by far worse, but people seem to forget that and think batteries are the new Hindenburg because they dont understand it.