“What’s the range like?” This is usually one of the very first questions asked when discussing electric vehicles, and one that’s often seen in the online comments about the Rosenbauer RT/RTX (Revolutionary Technology).
In the context of a firefighting vehicle, which usually has a lower range due to its limited area of application, it is less about the miles driven than the working time on site and its long-term operational capability.
However, the range of electric vehicles has already become a key comparison indicator, and in this blog post I would like to discuss this in more detail.
“Less” is often “more”
The Rosenbauer RT/RTX is a vehicle completely developed by Rosenbauer from the ground up, with the dimensioning of the high-voltage battery storage being a central and much discussed topic during development.
As is generally the case with electric vehicles, the battery capacity primarily determines the range. Other influencing factors include the driving style and speed, vehicle weight, route, and ambient temperature. Consumers within the vehicle, such as in-cabin air conditioning, and pump operation at the site, can also have a limiting effect on the range. On the other hand, recuperation, i.e., the recovery of braking energy, can slightly increase the battery’s charge.
It is therefore clear that a larger battery storage capacity also enables a greater range. However, this is in conflict with other aspects that are important, particularly in the case of a firefighting vehicle. It is critical to find the optimal balance of maximum electric range or electronic operational duration vs. spatial requirements, weight, and cost of the battery or batteries. A lower battery capacity may actually be beneficial for the user. A lower battery capacity means more space for equipment, more payload for extinguishing agents and devices, and more cost savings on the purchase.
But how much is low enough, but still more than sufficient?
In order to answer this key question, it is necessary to adequately research and discuss how an electric firefighting vehicle is actually used on a daily basis. What is the usage profile and range of applications of a fire truck? How often and how far does it drive every day? What are the on-site performance requirements, such as on the extinguishing equipment? How often and for how long is the vehicle in the fire station between calls to recharge its battery? What charging infrastructure can be installed in the station, and with how much charging capacity?
There are also requirements from standards. For example, the currently valid EN1846 for firefighting vehicles stipulates that a fire engine must be able to drive for 300 km or pump for 4 hours without refueling. The amount of energy required for this depends on countless factors, but can be estimated. Under the limits stated above, this requirement means an available battery capacity of approx. 250-300 kWh for a purely electric firefighting vehicle, but at the same time, the requirement for this is approx. 3,000 kg in weight and a considerable loss of loading space in the body, as well as additional costs.
100 kWh should make at least most of the operations electric
In close coordination with our lead customers, who already laid out the requirements for the pre-series vehicle during the development phase, a consensus was reached and a target was defined: 100 kWh should enable the handling of around 80% of operations by purely electric means.
With the RT/RTX, we offer customers two variants: single (66 kWh) and double (132 kWh) capacity, similar to the electric cars available on the market. This offers customers a certain degree of freedom for configuration of the vehicle, taking into account specified standards and individual payload requirements, and adapt it to an individual usage profile for their fire department.
So how far can you go?
As mentioned above, the range depends on several factors. In addition, there are still hardly any standardized testing programs for electric trucks, as exist for electric cars (e.g. WLTP – Worldwide Harmonized Light Vehicles Test Procedure for passenger cars and commercial vehicles up to 3.5 tons). So in order to be able to make a statement, we are dependent on the experience that we ourselves have accumulated during test drives, carried out by different test drivers under a wide variety of framework conditions.
In the RT/RTX configuration with one or two battery storage systems, an electric range of up to 50 or 100 km can be given as a guideline.
But what happens if the battery is empty?
Well, a fire truck must always be ready for action and also be disaster-proof. So it was clear from the start that a secondary energy supply had to be installed in the vehicle. A high-performance and compact diesel engine (225 kW, 6 cylinders, 3.0 l) is used in the RT/RTX as a range extender, which, in conjunction with an electric motor/generator, ensures a sufficient supply of energy. Automatic activation once a low battery level is reached ensures that it is not only used as a last resort, and that the battery is not completely drained. With this integrated power station, the vehicle can recharge the battery while driving, but also on scene. The diesel tank has a capacity of 125 liters and can be refilled as required in the same way as with any conventionally powered vehicle. This ensures a permanent supply of power and thus the vehicle’s continued operational readiness.