Guidance for Canopy Over Li-Ion Battery Storage?

12/30/2022

I am currently in the beginning stages of design for a 200,000 sqft warehouse which will be used for production and assembly of electric generators (picture the gas/diesel trailer-mounted generator you would see on a construction site but battery powered). There will be three separate areas where the batteries will be stored.

The overhead system will be an ESFR k-25.2 system.

The specs for the job are calling out a rated, freestanding, sprinklered canopy structure above the battery storage areas as an additional requirement to the overhead system which does make sense to me.

Is there anyone who has advice or experience with this type of commodity and coverage of it?

What code references should we be looking at, if any exist?

FM Global released a study on lithium ion batteries but from reading over it they were testing smaller power-tool-sized batteries and not large battery banks.

To my knowledge this is a relatively new hazard for the industry and the code requirements are having to play catch up. Again, any guidance would be appreciated.

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14 Comments

Pete H

12/30/2022 07:03:51 am

https://www.nfpa.org/News-and-Research/Data-research-and-tools/Hazardous-Materials/Lithium-ion-batteries-hazard-and-use-assessment

This is the most recent study I can find on it and it does include larger 20 Ah batteries.

I think at round 4 we'll get a solid commodity classification, and packaging will matter significantly.

sean

12/31/2022 05:32:24 pm

that study seems to focus on the individual cells being stored not assembled batteries

Franck

12/30/2022 08:28:08 am

When batteries are stored without being charged, it is generally considered as exposed group A plastic (to be protected accordingly).
Possible issue from the size of batteries as storage may be considered as storage with solid shelves…

Todd E Wyatt

12/30/2022 08:29:29 am

The scoping Code (e.g. 2021 IBC) identifies if an automatic sprinkler system is required for the Occupancy Classification(s) (OC). The manufacturing areas would be classified as Group F-1 Moderate-hazard Factory Industrial and the storage areas would be classified as Group S-1 Moderate-hazard Storage.

903.2.4 Group F-1
An automatic sprinkler system shall be provided throughout all buildings containing a Group F-1 occupancy where one of the following conditions exists:
1. A Group F-1 fire area exceeds 12,000 square feet (1115 m2).
2. A Group F-1 fire area is located more than three stories above grade plane.
3. The combined area of all Group F-1 fire areas on all floors, including any mezzanines, exceeds 24,000 square feet (2230 m2).

903.2.9 Group S-1
An automatic sprinkler system shall be provided throughout all buildings containing a Group S-1 occupancy where one of the following conditions exists:
1. A Group S-1 fire area exceeds 12,000 square feet (1115 m2).
2. A Group S-1 fire area is located more than three stories above grade plane.
3. The combined area of all Group S-1 fire areas on all floors, including any mezzanines, exceeds 24,000 square feet (2230 m2).
4. A Group S-1 fire area used for the storage of commercial motor vehicles where the fire area exceeds 5,000 square feet (464 m2).

Assuming that the “200,000 sqft warehouse” includes F-1 & S-1 OCs in excess of the areas listed above, the building would be required to be protected by an automatic sprinkler system (ASPS).

Assuming that the “rated, freestanding, sprinklered canopy structure above the battery storage areas” is for sheltering the batteries at an exterior space, the 2021 IBC does not address ASPS protection of exterior spaces.

For protecting “canopies” with an ASPS, see “Are Fire Sprinklers Required for a Canopy?” (https://www.meyerfire.com/blog/are-fire-sprinklers-required-for-a-canopy)

Eric R

12/30/2022 09:03:58 am

When you say storing "batteries" you need to be very clear on if these areas are holding bulk lithium-ion pouches/packs/cells, or if these areas are storing pre-assembled battery ESS modules (usually in metal cases with associated BMS circuitry for sliding into racks.

If this factory is building generator units it is (possible)likely that they are buying the battery modules pre-made. These devices have a very different fire profile from bulk battery pouches in cartons as described in the NFPA link Pete posted. These modules may already be at a 50% state of charge, and further the individual metal cases may slow down initial fire spread a little but at the same time act as a shield preventing the pouches from being directly cooled by the water spray.

Beyond reading up on the bulk storage testing, I definitely recommend reading this study from FM on ESS systems as it may be more applicable to pre-assembled battery storage(OR NOT!)

file:///C:/Users/Eric/Downloads/Development_of_Sprinkler_Protection_Guidance_for_Lithium_Ion_BasedEnergy_Storage_Systems%20(1).pdf

Of particular concern is this finding from page 56
"This test result strongly suggests that the batteries in the target rack underwent thermal runaway reactions during the initial fire in the main ESS rack. The cooling provided by the active sprinkler system may have slowed the development of the target rack fire but was not sufficient to prevent fire spread.
Thus, unlike the LFP case, the sprinkler protection was not able to suppress or control the fire. "

Not being able to suppress or control is a pretty big deal since it leads to lots of excess heads opening. I'd be concerned that if these shielded fires burn excessively and can't be cooled by the system under the canopy then excess heat will roll out into the ESFR system and you suddenly have a whole lot of big K-Factor heads dumping water for no benefit.

This is all very cutting edge so I certainly don't feel like I can give you concrete answers on how to solve this problem, but here are a few things you'll want to discuss with all stakeholders.

1. Are you sure ESFR is the right application for the overall building hazard? Any fire that might be shielded or have long internal burning characteristics might not be suppressible and a control mode design may be better suited to keep the fire area contained while waiting for direct FF response.

2. Check the battery chemistry being used! Lithium Iron Phosphate batteries have completely different fire characteristics compared to lithium nickel oxide (and other similar chemistries)

3. Consider an entire cut-off room instead of just an open sided canopy, this might really help control unnecessary sprinkler activation similar to there use in flammable liquid storage scenarios.

Good Luck!

Jay Whisenant

12/30/2022 09:52:35 am

Please see International Fire Code Chapter 12, 2021, and recent code changes to the 2024 edition. NFPA 855 is a new standard for installation. UL 9540, 1973, 1642, and 1741 are background on LI-IO batteries and testing, although not directly applicable to your situation. What they show is these are very nasty fires when they occur.

12/30/2022 10:12:36 am

Is there a way to access the 2024 edition changes yet? I thought we were still many months away from seeing the books made available?

12/30/2022 10:35:22 am

The applicable Codes and Standards are those that are adopted by the jurisdiction at the date of Plan Submittal for permitting purposes.

While "future" Code development can be reviewed to see how they are (proposed in) being revised, they are not applicable for compliance in current design projects unless the date of Plan Submittal is to occur when they may be adopted.

Most jurisdictions permit Design Professionals in using the previously adopted Code/Standards for a defined period of time during this time of new adoptions.

Just because the ICC/NFPA publish "new" Code/Standard editions does not mean they are required to be followed.

Dan Wilder

12/30/2022 10:28:28 am

Get an FPE, insurance agency, and the local AHJ to all agree to design intent prior to design. Clearly designate areas of storage, battery size and expected charge %, wall ratings, egress, packaging, detection, and smoke/heat mitigation (to name a few items). The 3 areas may require different approaches due to the assembly process...raw stacked/palleted materials, assembly where I have seen the outer casing look like bin box storage (ESFR usage), charging/testing areas, final packaging....

You are correct that NFPA is lagging behind a bit on this and the only criteria in 855 is more geared toward ESS that are in operation, not the assembly of them which would fall back to the material type and storage arrangements.

1/2/2023 08:12:18 am

The main issue is that the FPE will have no guidance at all to make his assessment... I really wonder on what he will make his evaluation...
Most automtove industries at the moment are considering the storage of batteries as exposed plastic storage (no thermal runaway is normally expected, and the fire behaved as a plastic fire).
On bench test, when batteries are charged, but only one battery involved, they are normally using the guidance as for ESS in NFPA 855, i.e., a density of 0.3 gpm/sq ft over 2500 sq ft.
This may also be the standard (in the future) for Electric Vehicles in parking structures. If not more !

Daniel Garcia

12/30/2022 01:28:32 pm

See NFPA 855 (2023 edition) section 4.9.2 for requirements. If the batteries have a maximums stored energy less than 50 kWh, you can use a density of 0.3 gpm/ft^2 over the area of the room or 2500 ft^2 (whichever is smaller). If the stored energy exceeds 50 KWh, you need fire and explosion testing data to determine the density.

12/30/2022 02:08:01 pm

Remember that 855 is only for ESS systems in an operational use environment. These design criteria are based on relatively specific arrangements. These setups are generally not more than 8’ tall, and with requirements for spacing of rack groups to prevent fie jumping.

The fire testing done in the process of making 855 certainly sheds some light on how the modules burn individually, but you can’t really extrapolate that to 12’ tall palletized stacks of them in a storage environment.

This is unfortunately something that just hasn’t been specifically tested yet. I don't envy the FPE or the designer in this situation. When you are working with so many unknowns there is a lot to be said for finding ways to mitigate the hazard without just increasing sprinkler flow. Lowering storage heights, increasing pile separations, fire rated rooms, or hell just build a separate structure on the lot so that way you don't lose your 200k warehouse when all the theoretical number crunching turns out to be insufficient.

12/31/2022 05:29:37 pm

codes have not covered this you will need to get a PE involved

Alex

1/5/2023 09:36:43 am

In further reading of NFPA journals and fire studies with respect to lithium ion batteries. adding water can exacerbate the flame spread and heat production.

You want to control the fire quickly.

I have an online retailer and they have batter storage and charging system and we specified a FM-200 system.

The use of water sometimes is not the best option especially here with lithium ion batteries in which water can make it worse even if you use high volume.

Take a minute to read the studies.

Guidance for Canopy Over Li-Ion Battery Storage?

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