A crew was carrying 384 battery modules down to the basement of a government data center in Daejeon to get them away from the servers, and the move itself knocked the country’s public services offline for weeks

Thirteen workers were on the fifth floor of the building that runs South Korea’s public services, and the job that night was housekeeping.

The battery bank sat about two feet from the server racks. Somebody had decided that was too close.

So they were coming out and going down to the basement, one group at a time.

Let a tool or a loose lead bridge the terminals and the cell dumps current through almost no resistance, and the inside heats faster than the casing can shed it.

A technician started pulling cables off a terminal.

Sparks came off the post.

Inside a minute the module next to him was venting gas, and the thing the move existed to prevent was already underway.

Why pulling a cable off a charged cell starts a fire

A lithium module holds its energy whether it is wired into anything or not.

Disconnecting it does not make it safe. It makes it unsupervised.

Let a tool or a loose lead bridge the terminals and the cell dumps current through almost no resistance, and the inside heats faster than the casing can shed it.

Past that point the cell heats its neighbors, and in a rack of hundreds packed shoulder to shoulder there is no natural break in the chain.

Temperatures in that room passed 320 degrees Fahrenheit.

The gas a failing cell vents is flammable in its own right, which is why a runaway keeps reigniting long after the flames look beaten.

The one thing that would have cooled it fastest was the one thing nobody could use, because water would have finished the servers the fire had not reached.

What twenty two hours in a sealed hall looked like

Crews went in with carbon dioxide.

The fire took hold at 8:20 in the evening and was not called fully out until six the following evening, 22 hours later.

All 384 battery modules were lost.

By that second evening more than half had been carried out, and they went into water tanks for two to three days so they could not light again.

The technician went to hospital with first degree burns to his face and arms.

Server halls are not built with room to work a fire. Racks stood roughly four feet apart, and the access firefighters needed was not there.

What the count showed once the smoke cleared

The building carries identity verification, the citizen services portal, postal logistics and emergency reporting, and 647 government systems went dark at once.

Ninety six were destroyed outright rather than merely interrupted.

One of them was the shared drive the civil service actually worked on.

It held 858 terabytes across 125,000 officials, close to eight years of files, and it had no backup at all.

The reason given was that the system was too large to back up.

Six days on, about a tenth were running again, and officials put full recovery at a month.

The suspect module went to the national forensic service, and a 20 member task force including three lithium battery specialists opened a criminal investigation.

The part that turned out not to be about old batteries

The first explanation offered was age.

The modules went in during August of 2014, more than a year past the ten year service life their maker recommends.

Battery engineers pushed back fast. A standby unit in a climate controlled hall sees almost none of the stress that ages a pack in a car, and age alone is a thin explanation for ignition.

What the investigation turned up instead was procedural.

Police said the batteries had not been discharged before the move, that required insulation materials were not used, and that the crew lacked the qualifications and the experience for the job.

The work had been subcontracted illegally through five companies, and employment records had been falsified.

Five people were charged with professional negligence, among them an agency official and three construction company employees.

The burns told investigators something on their own. A cell that lets go that much energy at a terminal was still close to full.

What the rest of the industry took away from it

Lithium was already taking over data center backup, projected at 38.5 percent of that market by 2025 against 15 percent in 2020.

Analysts at Everest Group read the failure as being about layout as much as chemistry, warning that over centralization invites systemic vulnerability and pushing operators toward distributed failover instead of one hall carrying a state.

Their recommendations run to isolating battery modules from server space, thermal sensing that catches a cell before it cascades, and clean agent suppression with high pressure water mist instead of sprinklers built for a different era.

On the day of the fire, a network operator in the United Kingdom gave communications providers 48 hours to strip lithium batteries out of telephone exchanges.

Korean operators began looking harder at chemistries that do not run away the same way, the road that pushed grid storage toward flow batteries and other designs built around water.

None of it answers the harder question, which is what a country does when one hall holds its entire public administration.

The same arithmetic now sits under every grid scale battery going up beside a substation.