We put a 15 kWh battery storage system in our garage and had to build a fire-rated room around it with a 60-minute fire-rated door to maintain code -- which is a pretty heavy weight steel door. It wasn't easy. All to maintain county code. The funny part is by the time we got the inspection, the fire department had a new inspector and he said "wow, you did all of this for the battery?"
Wow. And you can park a car that has a battery with 5x the potential energy in my garage without any additional requirements? Somewhere or another the code doesn’t add up.
5x more usable energy. Energy density of Li-ion cells improve by couple digits or so? if set on fire in expendable mode, if I'm skimming this[1] right.
I think the op is pointing out that some building codes put huge restrictions on building isolation with stationary storage like powerwalls, but as soon as those batteries are on wheels then regulating cars is someone else's department.
The gas tank doesn't have its own ignition source and oxygen built right into the fuel storage area like a battery does. Leaking gas doesn't all but guarantee a fire the way leaking electrons do.
Don't you remember the fire triangle from grade school?
Gasoline in a tank does not burn. Some welders will even weld a tank full of gasoline - it is a safe operation (most welders will refuse to do this, but a few will). The only time a tank of gasoline is a worry is when there are only a few drops in the tank.
The above is simple chemistry, the Stoichiometric air fuel ratio for gasoline has a very narrow range where it will burn. A tank of gasoline will be above this and thus not burn.
Also a good point. If each gallon of gasoline is equivalent to about 33kWh of energy, I could have 1.3MWh stored in two ICE powered cars. I guess it’s harder to put out a battery fire than a gas fire?
The way you put out a battery fire is you don't. Last I checked, the current best practice for an electric car that catches fire is to just let it burn to the ground while trying to stop anything around from catching fire.
Not to be callous but the "just let it burn to the ground while trying to stop anything around from catching fire." might be the structure over the basement in this case and the keeping other things from burning would be the surrounding buildings.
If firefighters can't access the basement safely, that's exactly what they'll do. They'll protect the exposures instead, ie the neighbouring buildings.
> I guess it’s harder to put out a battery fire than a gas fire?
Yep. With a gasoline car, dump water and foam onto the wreck and that's it. If you're really fancy install a sprinkler system in your garage - you can just DIY it if you want, hook up a water pipe to your water mains with a backflow prevention valve to prevent stagnant water from flowing back, add a few heads like [1], and there you go - assuming your water mains has decent pressure, that should be enough to keep a gasoline car fire in check for long enough so that the firefighters can show up and deal with it properly.
A battery car fire however? That one is much, much harder to extinguish and it burns way hotter. You need much more volume of water to cool it down enough to approach the vehicle safely, it will cause a lot more damage to surrounding structures, and fire departments haven't gotten nearly as much experience as they have with gasoline car fires.
That said, if I needed a car, I'd still go for an electric one, I'd just not park it in a garage directly connected to a home and certainly not in some basement garage.
People with ebikes generally charge a .5kwh-1kwh battery indoors every day. Any spare batteries after the initial bike purchase come from Amazon. At that energy density, is there any point to trying to contain a potential fire by, say, setting the battery inside a dutch oven? Or on a stack of sheet rock? Or would it burn well-past hot enough to ignite things outside it?
(edit: Dutch Oven has some thermal mass, but too much heat conductivity. Luckily, there is an actual product for this: UL-rated battery storage/charging boxes)
If you want to contain it a bit and you don't have a metal-fire extinguisher, dump a bucket of sand or fine salt over it. Commercial metal-fire extinguishers are nothing more than a dozen kilograms of dry, fine salt and a special low-pressure nozzle that allows depositing a "layer" of salt on the burning metal fire that melts and thus contains the fire. However it's hard to keep dry enough that it doesn't aggregate over time, reducing the effectiveness.
Personally, I recommend anyone charging serious amounts of unprotected or questionably protected lithium cells in a residential structure to, first of all, not charge them while you are asleep, and to keep a 10-20 liter bucket of sand nearby. Throw it on the burning battery if you can (you should be able to hear the battery go off maybe 30 seconds before it does go off), then run for your life.
Right; a battery box isn't for throwing a battery in after it starts combusting; it's for putting it in every time when you charge it, so you don't burn down the entire apartment building while running away.
A car itself contains a lot of stuff to burn (tires for example, etc) - look at any burnt out car - it is just a metal shell (until it was an aluminum one). So, i hardly see much difference between ICE and EV here.
The difference is you can extinguish a fuel fire by smothering it. Deny it oxygen and it can't combust. When you do that with a battery fire, it just flares back up as soon you stop smothering it
In theory you're right. On practice - until you're an equipped firefighter, you wouldn't be able to do anything once a regular car develops significant fire.
You can absolutely extinguish a fuel fire early on if the tank has not ruptured. Sand, baking soda, water, dirt, blankets, all work. If the battery on an EV develops an entire short you are not extinguishing it. If it were available, the safest mechanism would be to push it into a hole and bury it
Eh, a 5lb extinguisher in good hands has enough punch to extinguish a flaming stock tank of diesel twice so it should put out a car that isn't totally engulfed.
Source: Got to watch a demonstration put on by the local firefighter training center.
Source 2: Anecdotal experience buying burnt out vehicles at auction, the state trucks with extinguishers are typically only a little burnt.
i would have had to drywall the entire garage (which is pretty large) including ceiling in 3/4" fire-rated stuff which is a lot heavier. What a pain. So I just walled right around the battery a little closet instead.
How much did that cost, as a percent of the total cost of the system you built? My feeling is that a requirement like that could make the project financially infeasible for a lot of people.
Consider the U.S. insurance industry and their desire/need to refuse payouts when possible. If a fire occurs and the location contravenes just about any code their staff can find, they will likely refuse payout and it will be time for you to lawyer up. So, in that case, the expense of that special room might be seen as a bargain in the long run.
Sure, I don't disagree with that, but someone looking to do an installation might just decide not to do it at all, seeing the cost of the protection setup. That may or may not be rational, but I could easily see that happening. Sticker shock is a thing, and solar+battery installs are already plenty pricey, even with the cost renaissance we've been seing.
GP/sibling says it added on another 5-10% for them, though, so that's not too bad, though I guess it was a DIY job, and would have cost more to pay someone else to do it.
