Mercedes Benz, Trucks

The Whole Process of Charging a Truck

The Whole Process of Charging a Truck

The test drive of the new eActros was an opportunity to actually go through the whole process of charging a truck up. The truck has to be shut down, but unlocked to be ready for recharging.

The driver simply pulls the charging plug from the charger and plugs it into the charging port on the side of the vehicle. a set of pins automatically secure the charging plug in place.

Around the socket the lights begin pulsing in orange, indicating that there is now communication between charger and truck and getting all the technical information. The system is checking out which truck it is and the level of charge in the battery.

In this case, the charger tells us it can charge as a maximum of 260kW. This is the handshake process the system goes though before any charging takes place.

When the charger knows the cable is correctly plugged in and it is safe to proceed, the light around the charging socket goes green and the process begins. Inside the charger there’s a whirring noise, but the only real indication anything is happening is the green light at the socket.

Image: Daimler Truck

In the background, there is an overall charging management system which will have overall control of all of the chargers on a particular site. The operator can then prioritise different charging regimes to get the best efficiency out of the set of chargers.

Some may choose to ensure the system fully charges priority trucks and will charge other after the priority trucks are fully charged, or the strategy may be to ensure all of the fleet gets to 80 per cent charged, before moving to fully charge all of the trucks.

Charging a battery from 20 to 80 percent charged can be relatively quick but getting them from 80 to 100 percent can take longer, and use more electricity.

The driver can also set the maximum charge required, as a percentage, on the truck’s dashboard. This can be useful for an operation which may travel on some long downhill stretches of road, early in the journey. In that case the truck can top-up from using regenerative braking on the way down, getting the energy for free, from gravity.

On the dash, the truck will tell you at what speed it’s charging and when it will be finished. It is even possible for the operator to set the departure time. Before the truck is started it will precondition the battery, making sure it is already at it’s ideal working temperature, between 20 to 25 degrees C.

It can also turn on the air conditioning or heater, whatever would be appropriate. When the driver arrives, everything’s ready to go but using mains power rather than using the battery.

The electric system produces 600 volts, but there is a DC to DC converter, dropping the voltage down for the 24 volt electronic system for lights and control systems, which are the same as on the diesel version.

Image: Daimler Truck

Each of the main batteries has its own battery management system and they’re mounted across the truck slung beneath the chassis rails. There are acceleration sensors which will measure any side impact onto the batteries. If there’s an impact, the sensor will pick it up and kills the electric system.

Each battery has got a little chimney through which any smoke around the battery would flow. These chimneys are fitted with a smoke detector and if any is detected, it also kills the electric system. If the battery cells are in the early stages of a runaway, killing power is the best way to stop it.

There’s also a manual switch inside the cabin for the driver to be able to kill the electric system if there is anything amiss. When you turn the start/stop button off the electric system is already disconnected.

There is another way to disconnect it if it may be a problem getting into the cab. There are two cable on either side which could be cut by any fire services, and this disconnects the high voltage as well. The fire services have been trained up on this by Daimler Truck.

At the end of the day, this test drive gives a fair idea of the typical day’s drive for a driver working in an electric fleet. The driving is different, but adapting to the new technology is relatively painless.

The relative silence in the cabin is going to reduce stress and the ease of being able to control the truck safely and efficiently just with the two pedals makes life a little less complicated.

 

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