Li-ion and Li-Po Battery Safe Charging and Storage solutions for preventing fires and reducing toxic fumes for Lithium Ion and Polymer Batteries
- Mar 25, 2024
- 6 min read
Updated: Mar 31
DISCLAIMER:
The following info is documentation for scientific research purposes only. Do not attempt to recreate any of the equipment described. We are not responsible for any damage caused by information documented here. Read at your own risk.
DESIGNING A LITHIUM ION CHARGING CABINET
Lithium Ion battery charging cabinets that can contain a fire and smoke from a battery catching fire are very expensive... for good reason. It's very difficult to contain and prevent the spread of a lithium ion battery fire, and even more challenging to block, filter, or exhaust the toxic fumes.
The most promising "passive", no maintenance solutions are those created by CellBlock, using their expanded glass granule media. This media can encapsulate and stop the fire, and also block the smoke. The media doesn't expire, unlike other fire extinguishers and carbon based filtration systems. Cellblocks solution seems like a good compromise to stop a a battery fire and prevent spreading to other batteries.
Here are some videos of how it works:
Cabinet
E-bike battery charging rack
Cabinet interior screenshot from the CellBlock video and assumptions of the internal components. No claims are made as to the accuracy of these details, they are merely assumptions based on observation.
Commercial use by a business can justify and write off the cost of a Lithium Ion charging and storage cabinet. The cost may be out of reach for the average non-business related homeowner, so a homeowner is unlikely to be able to afford protection like this. Therefore homeowners remain at risk of Lithium Ion battery fires from consumer goods and especially Lithium polymer packs used for RC, airsoft and other hobbies. There are a pleathora of inexpensive fiberglass based pouches, but all they will do is slow down the fire. It eventually gets through those bags.
CellBlock sells the CellBlock EX expanded glass granule media in small to large bulk bags. These can be used as a firefighting agent, by dumping the contents on a Li-ion fire, or to create custom safety enclosures. Cellblock EX media is affordable, so we're going to design a DIY cabinet based on the CellBlock EX media used to stop Li-ion battery fire.
Screenshot from the Cellblock video showing closeup detail of the Cellblock EX media.
Screenshot from the Cellblock video showing the mesh burned through and the Cellblock EX media deployed through the holes.
Screenshot from the Cellblock video showing the cartridges being filled with media.
We're going to use an off the shelf enclosure as a base to modify into the Lithium Ion charging and storage cabinet. In this case I've selected the high quality, inexpensive US General tool chest sold by Harbor Freight. It's a well built, solid cabinet with good quality drawers.
This is how the stock cabinet appears.
The deep drawers are perfect height and size for charging and storage.
The shallow drawers are perfect for storing the CellBlock EX media, that can fall into and fill the deeper drawers in the case of lithium battery fire.
The first modification is to reorganize the drawers such that there's a shallow drawer directly above each deep drawer. Fortunately, a deep drawer is exactly twice the height of a shallow drawer, and the cabinet is predrilled for full drawer slide mounts, so the drawers can be placed at any position in the cabinet.
The shallow drawers will need to be modified to dispense the CellBlock EX media. There are several different ways this could be done.
Cut large holes in the bottom of the drawer. Place a mesh, like expanded steel into the bottom of the drawer. Place a layer of thin sheet plastic that will melt away from heat and flames. Fill with CellBlock EX. Cover with a fireproof, insulative layer, like ceramic wool, or cement board.
Cut a grid of many small holes into the bottom of the drawer. (Lots of work without a CNC). Place a layer of thin sheet plastic that will melt away from heat and flames. Fill with CellBlock EX. Cover with a fireproof, insulative layer, like ceramic wool, or cement board.
Cut large holes in the bottom of the drawer. 3D print cartridges that can be filled with CellBlock EX. The bottom of the cartridge has a grid pattern with thin areas that will melt quickly and dispense the CellBlock EX. This approach is modular and contains the CellBlock EX media.
Fireproof, insulating drawer dividers should be used in the deep drawers. This will isolate the batteries from each other, and reduce the risk of a chain reaction.
The drawers are self locking, but it is just a simple plastic latch that may not be strong enough to resist the explosion force of a battery. The drawers have a key lock also, which again may not be strong enough.
There is a small gap between the drawers that may be large enough to vent gassed to prevent pressure build up.
1 or 2 steel cabinet style locking doors can be added to the face of the tool box to further enclosed the drawers. Carbon filtration system can be added to that door.
AC Power To Drawers
Charging inside a drawer style cabinet has the complexity of running power to the drawer. Harbor Freight solved that in one drawer of their larger tool box, using a cable chain that moves when the drawer opens and closes. A piece of sheet metal above the cable chain guides it and prevents it from rubbing on the drawer above. Unfortunately this doesn't come with the smaller toolbox we are using, and not sold separately.
There are some cable chain outlets available designed for drawers, but they're designed to be attached behind the drawer, unlike the HF version that goes in the drawer. There is some space behind the toolbox drawers, so this may actually work great.
The HF style drag chain installation can be DIYd using an off the shelf 10x15mm drag chain. Need to add a piece of sheet metal (or 3D printed clips) at the top of the drawer to keep the drag chain from rubbing on drawer above it.
ENCLOSURES
Ammo Box Style Enclosures
Ammo boxes have been proven to contain lithium battery fires.
The gasket needs to be removed to allow the box to vent. That means that toxic fumes and smoke will still escape and damage the area they are in. Flames can also shoot out the gap between the body and lid and burn things closeby.
Adding insulation on the walls using cement wallboard or ceramic wool insulation to reduce the heat transmitted to the outside of the box. Ceramic wool needs to be encapsulated to protect the fibers. A 3D printed inner box could "encapsulate" the ceramic wool.
Adding dividers for multiple batteries. Dividers should be made from a fireproof material, like cement wallboard or ceramic insulation board.
Add a vent filter to reduce toxic fumes. Vent filter housing and connection need to be made of metal.
Add a layer of CellBlock EX under the lid. 3D print a cartridge with holes and a thin film that will melt/burn under low heat. Heat and fire from battery will melt through the film and the CellBlock EX will fall onto the battery, encapsulating the fire. CellBlock EX also significantly reduces the amount of smoke emitted.
3D print floor and walls that are filled with Cellblock EX. The 3D print should be thin enough to melt from the heat of a battery on fire. The CellBlock EX will provide insulation and encapsulation of the fire.
Standard 50cal Ammo Box
Heavy Duty Metal Ammo Can, Tactical Waterproof Lockable Ammo Crate. Outer dimensions measuring 16" x 5-1/2" x 9.25" (L x W x H) and inner dimensions at 14” x 5” x 8.5" (L x W x H) The advantage of this box is that it is shallow, wide and deep. That makes it easier to use the room inside.
FILTERS
The enclosures need ventilation, which also requires filtration to reduce the toxic fumes being vented.
Organic vapor and acid filtration
The canister needs to be metal so that it doesn't melt
Unless kept sealed, the canisters need to be replaced every 1-2 years.
Off the shelf filter options
EXTINGUISHING FIRES
CellBlock EX is made from expanded glass granules. When poured on a lithium battery fire, it melts, absorbing energy from the fire and cools, hardens and encapsulates the fire, preventing further combustion.
Affiliate Disclaimer
The products shown here were purchased by me with the intent to use them. I did not receive any free items, and I am not being paid or compensated for this review.
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