The plate number has a room temperature behind it

Every watt rating is a conditional statement. 2,500 W continuous is true under conditions the datasheet names once, in a footnote if at all: an ambient temperature, a mounting position, and air allowed to move past the case. Take the conditions away and the figure reads like a promise, which is how it ends up in a load list.

Two units with the same plate can behave differently on the same afternoon. One stands in the shade of a trailer at 28 °C; the other on a steel deck in the sun at 45 °C with a wall behind it. Nothing on either nameplate separates them, and the work they can do is not the same.

What the datasheet does not print beside 2,500 W

Ask for the second number in writing. For anything that will stand in a hot place, the useful figure is output against ambient: what is available at 35 °C, 45 °C, 55 °C. A supplier who cannot produce that table is telling you how the rating was made.

The peak is even more conditional than the continuous figure. Here it is 5,000 W for no more than ten seconds, and the bracket is the whole content. Ten seconds covers a motor start; it does not cover a compressor cycling every four minutes on a roof in August, when the case never recovers between starts.

Where the heat leaves the case

No fan means the case is the radiator. No intake and no moving parts is why dust and moisture cannot block a cooling path that does not exist. The same property has a second consequence: no forced air makes up the difference when the surrounding air is already hot.

Placement changes the ambient more than the weather does. A unit with a metre of free air and a light cover above it lives in another climate from the same unit against a wall, under a tarpaulin, beside a compressor, or on a trailer bed that has been in the sun since morning. IP54 covers dust and splash, not thermal headroom.

The shift is planned in hours, not in watts

2.7 kWh is fixed; 2,500 W is not. The energy in the pack does not change with the weather, so that is what a shift can be built on. Convert the list into hours: 900 W for three hours, a 400 W pump running half the time, lighting for the dark end. The peak rarely ends a day; the sum does.

Measure the load at 14:00, not at 07:00. Tools draw more when the material is hot, a pump works against a lower water table in the afternoon, and a unit comfortable at daybreak sits in its own heat by then. Recharge from a 230 V socket draws 500 to 1,500 W, and two hours to 80 percent is a normal-condition figure, not a promise for a pack that comes back hot.

The test record is a floor, not a curve

The over-temperature test proves protection, not output. Every unit runs a ten-point protocol in our own plant, and one point is an 80 °C over-temperature check. That shows the machine shuts down before the cells are damaged; it does not show that 2,500 W is held at 45 °C.

The protocol also checks derating stability, which admits the behaviour is real. Output falls as the case warms, and the test asks whether the fall is orderly rather than a collapse. CE under the EMC Directive 2014/30/EU with report A2409245-C01-R01-V1, and packaging under UN 3480 class 9, describe compatibility and transport — not a thermal rating.

What this is not — and what to send us

This is not a derating percentage we are printing here. We will not invent a curve in a note. The claim is narrower: the second number exists, it belongs in the quotation, and a buyer in a hot market should refuse to sign without it.

It is not an argument for the next class up, and not a reason to keep the diesel. A larger unit in the same sun has the same heat path and more loss, and the engine on that bench derates too, with its own curve and an intake pulling 45 °C air through a dusty filter. Nor is this a UPS: it feeds its own outlets only.

Send the air temperature at 14:00 where the unit will stand. With the load list, the running hours of each tool and the distance to the work face, the configuration can be settled against the second half of the shift. A photo of the position says more than a paragraph: https://www.hitama.net/en/contact.