CATL has two cell lines on trial in Debrecen

CATL started trial production of battery cells in Debrecen on 22 September. Two lines, in the new cell building. The company said so that morning.

Trial, in CATL’s words, is the work of setting up, optimising and validating the equipment before series production. The statement does not say when series production starts. It does not say what the two lines can make in a week. The 100 gigawatt-hour figure is the plant once every facility is ready, and the point at which Debrecen would be CATL’s largest base outside China. It is not a number you can take off those two lines.

22 Sept

Trial production started

2

Cell lines now running

100 GWh

Nameplate, once the whole plant is built

537,000

Modules made in Debrecen since autumn 2024

The module line was already running

Debrecen has been making battery modules since autumn 2024. CATL says it has produced 537,000 of them. A module packs cells that already exist. It is a later step, and it was the only step the site could claim until last Tuesday.

The cell is the step that changes a sourcing plan. Coating, filling, formation. Formation is the charge and discharge that shows whether the cell holds what the design says it holds. A line learns its scrap rate there. CATL has not published a yield, a scrap figure, or a date on which a European car plant can call a Debrecen cell a qualified part. The statement says the lines are there to prove the process. That is the right description of a first week. It is a thin description of a supply.

The date that was missed

The plan, as the city of Debrecen recorded it from CATL’s own briefing, was a €7.34 billion plant, 100 gigawatt-hours when finished, and almost 10,000 jobs. CATL told the city it had picked the Southern Economic Zone because raw materials were in reach, because Hungary already built cars, and because suppliers and customers were close. The same note said mass production could start in 2025. It did not.

The building took the time the process takes. Construction of the first cell hall began in the summer of 2023. By the spring of this year the equipment was in. The occupancy permit came in August 2026, and only after Hajdú-Bihar County had been through the site and said earlier faults were closed. Trial started on 22 September, on the first two lines, once the conditions on the pollution permit had been met. Three years from the start of that hall to a line that is allowed to run, and the line is still a trial.

The city also wrote down the power. Eighty megawatts for the first phase, rising to about 240 megawatts by the third, with the investor wanting 300 megawatts of supply in hand so the site would not be short. Those are planning figures from the briefing, not a meter reading from last Tuesday. They are still the right order of size. A cell plant of this ambition is a grid customer before it is a car customer.

Jobs were part of the same briefing. CATL said it would hire Hungarians first, and that it would work with local colleges so the plant was not staffed entirely from outside. Almost 10,000 people, by the end of the decade, was the figure the city wrote down. The 22 September statement does not say how many people are on the two lines this week, or how many of them are local. A nameplate of 100 gigawatt-hours with no headcount is a plan. A trial with no headcount is a building that has been allowed to start.

The county’s interest has not dropped because the permit was signed. CATL says that through the trial it will monitor health, safety and the environmental numbers, send the results to the authorities, and let inspectors in at any time. That is the company’s promise, and it is the right one for a site that had already failed an earlier inspection. It does not tell a carmaker whether the cell is good. It tells the town the line is still being watched.

What a trial line has not yet proved

A cell that is on trial is not a part number. Qualification, for anyone who has put a cell into a pack, is a run of formation data: capacity against the drawing, internal resistance, the share that fail, and a process that repeats on the next shift without a technician standing over it. None of that is in the statement. Nor is the customer. CATL says the modules already packed in Debrecen have gone to leading European carmakers. It does not name them, and it does not say the new lines are making cells for those programmes.

There is a practical difference between the two products on the site. A module can be built from a cell that arrives by truck. Moving the packing step closer to the car does not shorten the cell. The cell building is what would do that, and only on the day the cell is qualified, not on the day the trial is announced.

What can go on a plan

CATL says the modules already made in Debrecen go to leading European carmakers. It does not name them in this statement, and it does not say the new cell lines are shipping to anyone. A programme that needs a local cell still has to name the cell, the week it is qualified, and the line it comes off. Two lines on trial are the start of that work. They are not the end of it.

The 100 gigawatt-hours remains the figure for the finished plant. Anyone who booked Debrecen cells against a 2025 start has already spent a year on cells from somewhere else. The statement gives no new date to replace the one that passed.

For a firm specifying a pack, or machining and assembling around one, the week’s fact is narrow. Two lines went on trial in Debrecen on 22 September. The process is being proved. The series date was not in the statement. Neither was the output. The 100 gigawatt-hours is the finished plant.