Around three weeks ago, the explosion of a 30 kWh battery storage system caused a stir in Lauterbach, in the central German state of Hesse. The system owner is an electronics technician specializing in energy and building services, with 20 years of professional experience.
His home was destroyed in the explosion and it has not been habitable since. It is now in acute danger of collapsing, which is why police and insurance investigators do not dare to enter. This makes it impossible to determine the cause of the explosion with 100% certainty. The house will soon be demolished.
The homeowner told pv magazine that the battery energy storage system consisted of three battery packs from Shenzhen Basen Technology. He bought two in June 2022 and an additional one in June 2023 via the Alibaba platform. They are the “BR-48200B” and “MY-381” models, each with 10 kWh of capacity based on LFP technology housed in a 19-inch cabinet.
The battery system was coupled with a 15.47 kW photovoltaic system, which the homeowner was about to expand to 19.565 kW. The cause of the explosion has yet to be clarified, and there were no electrical clues, according to the homeowner. Right before the accident, the battery’s state of charge (SOC) was 90.2% and the voltage stood at 52.41 V.
After the explosion, the basement – which housed both the boiler and the battery system – was filled with white smoke. However, there were “hardly any signs of fire” near the battery storage unit, according to the homeowner. “The inverters on the other side of the room look like new,” he said.
Long after the incident, the homeowner noticed an odor that he described as the smell of lithium. He is now trying to determine whether it is makes sense to carry out safety tests outdoors for outdoor-use devices, as the smoke can evaporate and be overlooked. Now, the question is which gas caused the explosion, whether it originated inside or outside the battery, and how it happened.
pv magazine contacted two scientists, but the were unable to comment on the specific incident due to the ongoing investigation. Egbert Figgemeier, chair of aging processes and battery lifetime prediction at RWTH Aachen, said that it is conceivable that the electrolyte in the cells broke down and an internal short circuit ignited the gases.
“An external ignition source is not necessary,” said Figgemeier.
He described the white smoke as the decomposition products of the electrolyte, which can also contain dangerous gases. Soot formation is not necessarily to be expected, as many components of the cells could burn without leaving any residue at high temperatures. So-called thermal runaway could have preceded the explosion and may have been the trigger.
Popular content
Axel Durdel, a researcher at the Technical University of Munich, told pv magazine that in a “worst-case scenario,” an LFP battery could leak hydrogen, carbon dioxide, carbon monoxide, ethene, methane and other gases. There has been a lot of discussion about the possible formation of hydrogen with a subsequent explosion. In principle, this is possible, but whether the conditions for spontaneous combustion have been reached cannot be estimated, according to Durdel.
He said it is not known that batteries could cause such an explosion without a thermal reaction. In the case of thermal reaction, the internal pressure could increase due to undesirable side reactions, leading to an explosion and the release of hot gases.
“In the case of batteries with a lower energy density or a low state of charge, it is entirely possible that the gas does not ignite directly when it exits the battery, but that the ignition occurs through external ignition sources,” said Durdel.
In that case, there should be traces on the battery. However, this can no longer be verified because no one is allowed to enter the home due to the risk of collapse.
The storage owner has noted the problem of carrying out safety tests with lithium-ion storage devices outdoors. Figgemeier confirmed that such experiements are carried out in semi-open bunkers, rather than in closed rooms.
Durdel said that the standard-compliant safety tests for the lithium-ion cells are carried out almost exclusively in test rooms with appropriate filter systems. In principle, it is conceivable that gases could accumulate in the basement without an appropriate exhaust system. However, the scientist from the Technical University of Munich could not say whether this was sufficient for self-ignition.
Battery storage is generally safe when professionally installed and certified, with compatibility between systems ensured through testing and approval by inverter and battery manufacturers.
For integrated systems, this is done by the system integrator. The safety of these systems is evident in the low number of accidents reported among more than 1 million home battery storage installations in Germany. Monitoring systems, common among established manufacturers, further assist in the early detection of critical conditions.
This content is protected by copyright and may not be reused. If you want to cooperate with us and would like to reuse some of our content, please contact: editors@pv-magazine.com.
Looks like he was working the cells way too hard – that system has 3x Multiplus in the image, so is far too big for the battery capacity…and as such not anywhere the manufacturer’s recommendations. in that configuration it would easily be able to charge or discharge the pack much more rapidly than the batteries are designed for, resulting in cell imbalance and rapid overheating.
Poor system design and operation is likely to be at fault here rather than poor quality components.
Happy to get into greater detail if you need more info…we build Victron systems as a day job.
No, these batteries allow for 2C sustained charge, even if he used 10k multiplus, it should still be fine for a 30kWh pack at 90% SoC. Probably a defective cell expanded and increased pressure on the other cells causing a shortcut somewhere. The power of expansion is unstoppable. Since the cells are usually packed under pressure to extend lifetime, there could have been a sudden explosion of the enclosure that ignited some emitted gas
The explosion of the
lithium iron phosphate batteries, whether it was an isolated case or not is important to consumers of this product. More should be done to ascertain the cause for safety concerns of the users. Whether one knows the physics, and the chemistry behind the working of the battery or not is not important. Safety comes first.
I am very interested in the outcome of the safety test, and investigation. In as much as LFPs are know for safety, it is important that the facts are established. I realize that most LFPs are installed at confined areas. I think going the way of SMF batteries will advert this level of destruction.
No knowledge of what those poisonous escaping into our atmosphere might do to our frail ecosystem. Of course no investigation ever on that, it simply it goes against the GREEN ENERGY agenda. Well any way, in other news tonight we had another volcano erupt sending plumes of toxic gasses and carbon into the upper atmosphere. Politicians are calling for another round of tax increase for their GREEN ENERGY PROGRAM.
Everyone tends toward assuming it must be the Lithium batteries, likely due to the reputation of other Lithium chemistries. Was it daytime, with power pounding into the batteries? Were the panels divided between each battery, or was some sharing device used to input to each battery? Are the panels wired in series, with a possible overvoltage being presented to the batteries from a charge controller failure? Was the boiler running? Lots of questions.
Obviously, I would expect to see battery damage, but it says there was no signs of fire, on the battery housings. It’s known, that charging past 14.6 Volts damages LiFePo4, permanently, so somebody should be looking at that. I expect such a large bank, would fail quickly, if even a short high voltage condition existed on any single set of cells.
I did various searches on the internet looking for the certifications of the models indicated by the owner. No (!!!) safety standard certification can be found, specifically there is no accredited compliance with IEC 62619, which is the basic safety standard for Li-ion and Li (metal) batteries.
Whatever happened, if there was damage caused by the batteries this means that the BMS (Battery Management System) did not perform its functions (SIL = Safety Integrity Level functions, qualified in hw and sf via IEC 61508, IEC 60730 -1 (annex H) or similar).
Even if the combination between battery model and inverter was problematic, the BMS – battery safety system independent of any other safety function within the storage system) would have had to intervene. The models indicated are all for parallel connection, so each individual battery module has its own internal BMS.
The BMS isolates the battery in case of: undervoltage (overdischarge), overvoltage (overcharge), overcurrent in discharge, overcurrent in charge, undertemperature, overtemperature. E-commerce platforms allow the purchase of products that would not have a market in Europe because they do not comply with the most basic quality and safety requirements required in Europe, not only by regulations but also by manufacturers, system integrators and also by aware users .
Unfortunately we do not have any images of the battery room and the condition of the batteries. We have no information on the general system architecture. In one photo you can see three inverters: are they hybrid PV inverters that also connect the batteries, each connected separately to a group of batteries? or were there inverters dedicated only to batteries? if this is the case: were the three battery groups connected in parallel with each other or were there different converters for different battery groups? I say this because it is highly inadvisable to connect groups of batteries of different brands/models in parallel (even if of the same technology, e.g. LFP): normally to do this DC/DC converters (“DC-boosts”) are used to exactly align the tensions between all groups, because different models of the same technology (LFP) never have identical SOC/Vbatt characteristics.
A very strange thing is the magnitude of the damage, which is difficult to explain with the gases produced by only one battery, which would suggest that multiple batteries failed at the same time, which would be consistent with BMSs not doing their job…
I work in an BESS (Bettery Elecrical Energy Storage System) system integrator/manufacturer in Italy, and I am member of national technical commettees CT 82, CT 120, CT 316 and collaborate with CT 64 in CEI.
A problem with batteries with a nominal voltage of around 50V to be connected in parallel is that they are outside the scope of the so-called LVD (low voltage safety) Directive 2014/35/EU, which is only applicable for products with voltage between 75Vdc and 1500Vdc (and between 50Vac and 1000Vac). This has created a gray area, whereby compliance with the so-called EMC (electromagnetic compatibility) Directive 2014/30/EU is sufficient (!) for CE marking.
Batteries within the scope of LVD (V>=75V or to be serial connected up to V>=75V), have to demonstrate (!) compliance with the essential safety requirement 2.c) (Annex I): «persons, domestic animals and property are adequately protected against non-electrical dangers caused by the electrical equipment which are revealed by experience”, for which it would be mandatory to report in the EC Declaration of Conformity how the safety of the product was verified with respect to some specific dangers such as fire, explosion, release of chemicals/toxics. For Li-ion technologies this confirmation is given by qualification according to the EN IEC 62619 standard (latest ed. 2022, even if it is not an “harmonized standard” for the LVD directive in any decision act in OJEU).
Only for one of the two models indicated is available a CE declaration of conformity, concerning the EMC directive only.
The new Regulation 1542/2023/EU so-called “batteries and battery waste” will lead to resolving many gray areas on the regulation of battery safety, for the purposes of CE marking, even if the complete process will take a few years.
Is it possible there was a steam explosion from the boiler first and then damaged the batteries?