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?"
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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.
1: https://www.sciencedirect.com/science/article/pii/S037877532...
Typically the code requires 60-min firewalling of the garage.
For an EV?
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.
>For an EV?
For a 20 gallon tank of gasoline on wheels.
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 an option in the basement of a building, the temperature will risk structural integrity.
> 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.
[1] https://koka-shop.de/universal-sprinklerkopf-brandschutz.htm...
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)
> With a gasoline car, dump water and foam onto the wreck and that's it
Well yes, but you need a lot of water. Fuel fires are not something you can tackle with a domestic hose.
However as you point out, normally the reason for a battery fire is because it's shorted, so its not/less oxygen dependent.
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 after a ICE car burns there is a tank full of gasoline still there. With a EV the battery will also burn.
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
yes exactly we didn't want to firewall the entire garage so I built a structure around the battery.
A bunch of drywall around it?
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.
Code in what jurisdiction and for what application?
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.
5-10% of the battery itself. required 1/2" sheet rock, that 60-min door, etc etc. would have been more if I hired someone to do it.
sorry 3/4" sheet rock in case anyone is counting here.... :)
A lot of people probably don't follow the law.
correct. but a lot of people do. and it can be expensive.