How to build fire protective battery charger enclosure?
How to build fire protective battery charger enclosure?
In the last couple of years, I replaced all my lawn care equipment with battery powered and it has worked fantastically. I’m sure there will soon be other large batteries that need to be charged.
However I also note headlines about fires from cheap or damaged batteries. I don’t buy cheap and I do take care of my stuff so I’m not too worried but wonder if it would be worth building some sort of battery charging enclosure. Does anyone have any links, ideas or references?
My first thought is I have an unfinished basement with concrete walls and floor so that should be fire resistant: could it be as simple as stacking cinder blocks or pavers? My second thought is that would make a great oven, so no. So is there something I can do for my chargers to protect my house from any chance of fire?
I have been looking into this lately, it seems there may be some commercial options that are normally for industrial use. I found some on Amazon that seem too cheap for this.
As a firefighter I've been running a bunch of these battery calls. The best case scenario is they just smoke up your house., and worse case I've seen videos online of the room going from nothing to IDLH (Immediately Dangerous to Life and Health) in under 20 seconds.
We've had a ton of ebikes and scooters burn up in homes. Never charge those inside. I've see power tool batteries burn up huge sections of residential houses, and I've seen laptop batteries explode right under the feet of other firefighters. That last bit was super cool, rarely get to see explosions that aren't car tires popping. Those laptop batteries would have caused a huge amount of damage if the building wasn't made of concrete - they allow modern midrises to be stuck built!
You are wise to be concerned but I think you will not design an "enclosure" that will prevent further damage if it is inside a wood frame house. There is a house near me that burned down because of a single power brick for a tool in the garage.
Your better approach would be to make it so that power delivery is monitored and regulated automatically. That or manually just unplug after charging.
Thermal runaway happens on over-discharge or overcharge of the battery pack. Each pack has smart circuits to regulate this but they are designed at scale with a squinty eye at overall product cost...cheapest circuit available gets used even by well-known manufacturers.
Place power draw monitoring on the delivery circuit and when the draw lowers to maintenance level (batteries have recharged) have the power delivery automatically cut off. This can all be automated with freely available smart home products. You can even get some temperature sensors to monitor for overheat conditions during charging.
Yep, automation is part of the plan, as is additional smoke detectors.
I did look at basement ventilation too and I’m not sure I can do much there since the house is stucco over block (only the interior walls are wood frame). I have an existing vent fan out a window well, but I’d need to figure out how to weather seal it if I wanted to automate that …. Plus there’s no way it’s sufficient for a battery fire
Y'know - I think stacking cinder blocks and some pavers on top would actually work just fine. Just angle the cinder blocks so the ones at the bottom have the holes poking out (and into the enclosure) and that should provide enough airflow to keep it from getting too hot in there.
Heck, you could probably angle them all that way except for the top ones. I haven't seen videos of battery fires, but unless they're like really really flammable, the fire shouldn't burn out from around the several inches of concrete that surrounds it.
Remember fire burns up so the pavers and concrete blocks at the top will be what are actually blocking the most.
Yeah, maybe I’ll do this …. And hope to never find out if it works. This would be really cheap insurance
A small spot on the concrete floor with cinderblocks to make a table / shelf for the chargers and batteries should be fine, just as long as nothing flammable is within a distance that flames could reach it if the batteries caught fire in there (not by the wall or under something). I just keep mine on a shelf in the garage during the cooler months, but I bring them inside when it's hot.
But batteries stored directly on the floor is also bad, so you'd want something to set them on. Somehow batteries can discharge into the ground if left on a concrete floor. An old metal ammo can on a cinderblock would be good enough IMO.
But batteries stored directly on the floor is also bad
Not actually true
Well I've seen it happen myself, and I was learnt of it by an old-ass electronics engineer who did calculus equations on graph paper all day to solve microwave transmitter issues, and he was more knowledgeable about electronics than any other human being I've ever met so I'm going to continue NOT storing batteries on the concrete floor.
You can store your batteries on the floor if you want to of course, but you've been warned.
I put my RC batteries in an ammo can.
Are there safer, more sealed storage bins? Yeah,but there's only so much you can do.
Even assuming ammo cans scale up to my snow blower battery, they tend to be sealed, whereas I’d expect to most need protection (and ventilation) while charging
A fairly common solution is military ammo boxes. They are designed to contain ammo cooking off, as well as protecting their content from fire. They therefore deal with battery fires fine. Just make sure there isn't anything too flammable close to them, or above them. Any fire that happens will be directed upwards. Just line them with something not electrically conductive.
FYI, never put water on a battery fire. The water can react and make the fire worse. Instead use sand. It reduces flames and acts as a heat dump for the generated heat.
A good setup would be an ammo can for each large battery on a none flammable shelf (metal racking?), with nothing above it that can burn. A fire bucket of sand to hand, to control anything, and a smoke alarm will alert you to any issues as well. It's overkill, most of the time, but good for peace of mind.
That’s an interesting perspective: I had assumed the biggest risk was while charging, and wanted to set up something to control that risk. I do see one reply about automation to prevent overcharging and I’ll definitely do that, however had not really considered whole in storage.
I’ll have to look into that and how expensive it is for larger batteries
Take a look at cement board and the codes for your area for a wood stove.
There’s certain gap requirements for heat etc but you could rig up something fairly simply whether a box or more open enclosure.
There are also fire extinguishers that are activated by heat and sit above a potential fire source. People use them in 3D printer enclosures fairly often. Batteries burn for a long long time depending on how charged they are so it would have limited effectiveness.
This could actually be a really interesting and useful product idea. Maybe a kit with GFCI outlet, surge protector bar with fused outlets, huge spacing between outlets to allow for large plugs, metal/cement board case, wire shelving, ventilation fans to keep batteries cool but have louvre shut to cut oxygen for fires. Hmmm I want this for my garage.
Well, if we’re dreaming big ….. my gas water heater has a metal cage surrounding the burner section that is supposed to suppress the flame. Supposedly the cage removed heat or something so any flame didn’t extend beyond. I wonder if something like that would keep a battery fire caged
I use one of the oily waste cans for charging sketchy lithium batteries. While that would keep the fire mostly contained if something goes wrong, you still have a LOT of smoke/fumes to deal with, so a basement might not be the best spot unless it's ventilated well.