Lithium-Ion Batteries: Current Safety Knowledge from VdS, Europe´s No.1 for Fire Protection

On Jun 30, 2023

Safety for lithium-ion batteries: Unfortunately a definitely „burning“ topic. VdS, Europe’s most important institute for fire protection, and ISR, Indias most important magazine for this topic, offer you the current state of research and practice concerning potential hazards and, above all, protective measures. Most of them easy to ensure and implement.

The prime finding right away: each of us has heard about quite frequent and sometimes uncontrollable fires caused by this young technology. But we can say directly: there will also be some very good facts for safety responsibles here.

One after the other: Instead of the good usually harmless zinc-carbon batteries, which we can still marvel at in low-energy devices like our remote control, the much stronger, very long-lasting lithium-ion batteries are gaining ground in all areas of our lives – but are also named by experts as „hyper-sensitive divas who blow up at every little issue“ (Institute for Loss Research of German Insurers), significantly increasing the risk of fire.

In very short: a little physical background

The heart of this battery system are electrochemical cells, typically easily flammable electrolyte. One core problem is the (so far) unstoppable age-related destruction of the diodes´ separator.
And the battery cells are individuals, therefore age at different rates. While „young“ cells in the same battery have capacity and say „give me more“, „old“ cells are already overcharged, causing them to overheat. Same in the other direction with the dangerous deep discharge (more on this later).

So very unfortunately as a result of those physics, lithium batteries can fire up from a huge mass of factors the former zinc-carbon batteries did absolutely not care about:

Wrong handling
Mechanical damage
Thermic stress (many examples of cars / busses standing in the sun on a hot day and burning up, even exploding, from the e-motor or also just the small navigation system battery being „sunned“ up)
Inner AND outer short circuit
Overcharge
Depth discharge – yes, unfortunately this technology can fire up from being empty, possibly leading to spontaneous combustion. But basically the higher the charging level, the higher the danger.
Quick charging
Wrong charging equipment – at least one easy thing to prevent

AND due to the mass of dangerous chemicals contained inside the battery, in a fire we will have in the air – among further “strong contact poisons”: Hydrogen, explosive in contact with air and fire.

In Australia in 2021, it took 150 firemen 4 days to extinguish a 13 ton-battery. Even „better“, an extinguished battery can reignite anytime even days after a fire. If you want to check what the usual industry amount of batteries can do, please see minute 5:30 of this video of a quite easy, harmless fire in a warehouse reaching the lithium batteries stored there. https://www.youtube.com/watch?v=vQ1cabt3jXc

There was no warning for the firemen for the warehouse manager had stored huge amounts of zink carbon batteries for years and understandably did not realize that those standard products had with a new technology suddenly become highly flamable, even explosive.

Enough of those horror facts, here are now some good news – quoting the German Insurer Associations statement after conducting practical tests together with VdS: „When handled properly, lithium batteries do not pose any unusual fire risk; the technology is suitable for everyday use. So: Manufacturers, distributors and consumers have considerable responsibility when dealing with the powerful devices.”

When handled properly“ – what exactly does this mean?

The German insurers have bundled their findings and safety advice in a publication which can be downloaded for free here https://shop.vds.de/download/vds-3103en (or type „VdS 3103en“ into a search engine), recommending for example „General Safety rules which shall be observed at any time“:

“Incoming goods inspection shall ensure that only undamaged cells and batteries are stored, for which UN 38.3 is available as evidence of checking.” Special consideration goes for prototypes and returns.
“In any areas not protected by an automatic extinguishing system, a structural or spatial separation of min. 2.5 m from other combustible materials shall be provided for.”
do not expose to high temperatures or heat sources (e.g. direct sunlight)“; 60 °C is specified by well-known manufacturers as an upper limit to protect against capacity loss and increased fire risks. On the other side of the scale, also avoid exposing to frost. The longer low temperatures affect the cells, the greater the risk of capacity loss and dangerous cell damage. So do not store batteries in an unheated building part in winter, for example.
Adherence to the specifications of the respective manufacturer and technical product data sheets.
Prevention of external short circuits (protection against short circuit of the battery terminals, e.g. by means of caps).
Prevention of internal short circuits (protection against mechanical damage).
Immediately remove any damaged or defective lithium battery from the storage and production area and store this temporarily with safe distance or in an area separated with fire protection technology until its disposal.“

Always watch that the cells are „undamaged“ – which specifically means: A scratch is fine, no problem. If the battery fell down, check: Is it dent? Deformed? Performed? All bad, remove instantly! If it is swollen (with the picture IN SLIDE 6 not being a funny photoshop makeover): Treat it like a bomb – it now is one! The best way to transport such a damaged cell is a fireproof box, if not available a metal wastebasket covering the cell in sand (not water, for chemical reasons) is a “quick and dirty”, comparatively safe option.

Also very bad is a rapid temperature increase during charging or a suddenly empty battery; “browning” anywhere, also in the loading equipment (so it is a very good idea that many charging cables are now white, making this danger easily identifyable).

Charging is seen as most critical and should preferably happen only under surveillance and on a fireproof base – please remember this also for your mobile phones etc. back home. It should also be ensured that batteries have not previously been deeply discharged (like by limiting the storage time before charging to 6 months).

Easing your important safety work should hopefully be the battery classification listed in the VdS leaflet „Sprinkler Protection of Lithium Batteries“, free download: https://shop.vds.de/publikation/vds-3856en , or just „VdS 3856en“ for the seach engine): “in order to make the results of fire tests and existing concepts more transferable”. Since weight and size can vary greatly due to the different housings (e.g. pouch cells) “classification by energy content per storage unit (e.g. pallet) is more useful here. … usually classified according to their power (Ah). As the voltages can also vary greatly, the power has been converted to kWh.”

What to do in case of fire – very quickly:

A classical military claim dating back to the German freedom wars: „Be prepared that anything that can go wrong WILL go wrong“ which is still fully up to date. So a battery fires up – what is to be done in this case?

Very fortunately, the only extinguishing technology needed for a developing lithium battery fire is simple water. If efficient fighting of an initial fire succeeds in the first minutes – with rapid and targeted water –there is a great chance to get control. Very unfortunately a fire involving lithium batteries usually gets fully out of control within around 8 minutes – which is much less time than what is usually needed for first detection, then alarming, then for helpers or the fire brigade arriving and putting water on it.

Further very good news: sprinklers are working (TODAY – battery power is increasing by assumed 10 % every year, so all current safety concepts and most things you read in this article might be totally obsolete in the near future, sorry).

Severe VdS testing has proven in practice that the good old water extinguishing systems, VdS-approved for always optimal safety, are effective protection if designed so water will reach the source of fire quickly. Unfortunately, standard concepts for this relatively new batteries are not existing yet – a singular evaluation is always neccessary. Check Guidelines VdS 3856 for support, some core findings summarized for you here:

“Essential is strong cooling, water is favoured as the extinguishing agent for this cooling”. Because of the “thermal runaway” danger (stored energy released in an uncontrolled manner), cooling of the batteries not involved in the fire is also necessary. “So far, only rapid extinguishing with large quantities of water has proved effective.”

As for storage, please see that all devices are in drenchable packaging, stored energy per storage unit (e.g., pallet) shall not exceed 50 kWh, the rack design is according to Planning Guidelines VdS CEA 4001, K.7.1 and sprinkler protection is provided on every rack level. Of course, only store batteries with proof of testing according to UN 38.3, using only batteries from reputable manufacturers with appropriate quality and safety standards.

We hope this summary was helpful to our joint cause of protecting human life, nature and expensive goods from destructive fire and smoke – Namasté and best regards to all those working for the important safety!

Dr. Florian Scharr is coordinator customer relations at VdS, Europe´s No.1 Safety Certifier and partner of FSAI. VdS-approved products always cover EN, CE, CPR + mostly ISO, are accepted by governments all over the world and are fully NFPA compatible.