E-Trailers and Electric Semi-Trailers: Technology, Savings, Manufacturers, Costs

For many fleets, the fastest way to less diesel does not lead through a new truck but through a new trailer. An e-trailer with a driven axle and its own battery saves on average 40 percent fuel behind a diesel tractor unit – without a megawatt-range grid connection and without replacing the tractor unit. Which types exist, what they deliver and when they pay off.

Two types, two business models

Driven e-trailer

An electric axle in the semi-trailer, fed from a battery of 300, 450 or 600 kWh. Sensors at the kingpin detect whether the tractor unit is pulling or braking, and the semi-trailer pushes along or recuperates – completely self-sufficient, with no data connection to the tractor unit. It therefore works behind any tractor unit, whatever the make. The best-known implementation comes from Trailer Dynamics and Krone; the Krone eTrailer has been in series production since 2026.

Electric reefer semi-trailer

Here the point is not propulsion but the refrigeration unit. A recuperating axle and a smaller battery (around 23 to 32 kWh) supply the unit electrically instead of with its own diesel engine. Examples: Schmitz Cargobull S.KOe COOL (series production since 2022), Krone Cool Liner with Celsineo and AxlePower (since 2023), components from BPW and SAF-Holland. The background: a diesel refrigeration unit consumes 2 to 4 litres per hour – a considerable item for a reefer semi-trailer in continuous use.

What a driven e-trailer delivers

• Behind a diesel tractor unit: on average around 40 percent less fuel. Fleet measurements vary widely with route and driving profile – DB Schenker measured 24 to 55 percent, BMW logistics 48 percent.
• Behind an electric truck: 300 to 500 km of additional range, depending on battery size. This makes long-haul rotations possible without public charging that would not be feasible with the tractor unit alone.

What it costs

According to market observation, the extra price compared with a standard semi-trailer is around €90,000 to €140,000, the total price roughly €150,000 to €250,000. For the electric reefer semi-trailer, the premium over the diesel reefer semi-trailer is around €25,000 to €35,000.

The calculation for the driven trailer behind a diesel: at 120,000 km, 28 l per 100 km and around €2.02 net (German diesel price), a 40 percent reduction saves about €27,000 of diesel per year. Set against this are the electricity costs for the semi-trailer battery – a fraction of that with depot charging. All in all, it pays off from around 100,000 km per year, provided the semi-trailer stays permanently with the same tractor unit.

The limits

• Charging: the semi-trailer has to be charged overnight, so it needs a charging point at the depot – though at a much lower output than an electric truck.
• Weight: 1.5 to 4 t more, depending on the battery. In Germany, the 2-tonne rule for zero-emission vehicles applies only to the tractor unit.
• Trailer pooling: anyone who swaps semi-trailers in a pool or leaves them at the customer’s premises loses the advantage – the e-trailer only pays off if it stays permanently with one tractor unit and returns to the depot in the evening.
• Toll: a diesel combination with an e-trailer remains fully liable for toll. In Germany, the truck toll exemption depends on the tractor unit.
• Approval: check the type approval for each model, especially for cross-border operations.

Who it pays off for

The driven e-trailer is the interim step for fleets with a young diesel tractor unit, high annual mileage and fixed rotations – especially where a grid connection for electric trucks still takes months. The electric reefer semi-trailer pays off independently of the tractor unit wherever the unit runs for long periods. In the technology comparison, “diesel + e-semi-trailer” appears as an option in its own right with costs per kilometre; the profile check tells you whether your own operation suits an electric truck or an e-semi-trailer better.

And if an existing semi-trailer is to make way for the e-trailer: what it is worth today is shown by the free valuation; after that, verified dealers from 35+ countries make binding offers – sell your trailer with truckoo. More on body types in the article Semi-Trailers: Types, Dimensions, Payload.

Frequently asked questions about the e-trailer

What is an e-trailer?

A semi-trailer with an electrically driven axle and its own battery of 300 to 600 kWh. It pushes along when accelerating and recuperates when braking, controlled by sensors at the kingpin, and works behind any tractor unit.

How much diesel does an e-semi-trailer save?

On average around 40 percent behind a diesel tractor unit. Fleet measurements range from 24 to 55 percent (DB Schenker) and 48 percent (BMW logistics).

What does an e-trailer cost?

According to market observation, around €150,000 to €250,000, i.e. roughly €90,000 to €140,000 more than a standard semi-trailer. An electric reefer semi-trailer costs around €25,000 to €35,000 more than the diesel variant.

How much range does an e-trailer add behind an electric truck?

300 to 500 km additional, depending on the battery size of the semi-trailer.

Is a diesel truck with an e-trailer exempt from toll?

No. The toll exemption depends on the tractor unit; a diesel combination with an e-trailer pays the regular rate for its emission class (in Germany).

Which manufacturers build e-trailers?

Driven e-trailers: Krone together with Trailer Dynamics, in the USA Range Energy. Electric reefer semi-trailers: Schmitz Cargobull (S.KOe COOL) and Krone (Cool Liner with Celsineo and AxlePower). Axle components are supplied by SAF-Holland (TRAKe) and BPW (ePower), among others.