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How Temsa Developed Their Programmable Electric Bus

By Larry Plachno

Anyone involved in the bus industry is aware of the movement to battery-electric buses in recent years. There are several advantages to electric buses. While they are more expensive to buy, they offer substantially reduced pollution in operation and also tend to be more economical to operate and to maintain. Electric buses would be even more popular were it not for the fact that operating range is limited by battery capacity.

            While most people do not think of it, ­battery-electric buses differ from diesel buses in two major ways. The first is in the area of components. Various components on diesel buses are activated or get power in different ways. Steering assist can be hydraulic. Windshield wipers can be operated by electricity or compressed air. Air conditioning, compressors and cooling systems can be powered mechanically or by belts from the engine. However, since an electric motor does not operate continuously, belts and mechanical engine connections will not work for components in electric buses.

            As a result, components and systems for an electric bus generally have to be powered by electricity. For a bus manufacturer, this takes a great deal of engineering. You first have to find and decide on an electric component or system for your electric bus and then engineer it into the bus. This may be more difficult to do than you think since you also have to engineer space for batteries and their control systems. One positive factor in all of this is that the electric motor generally takes up less space than the diesel engine and eliminates a lot of belts, hoses and connections. The lack of several components and fluids such as fuel filters, antifreeze and engine oil is what helps make the electric bus easier to maintain.

            The second big difference between electric and diesel buses is that the diesel bus has a “one size fits all” advantage with its power system. You can buy a diesel bus off the lot and use it for a long distance tour, a one-day charter, running a route and for a convention shuttle. The basic engine and fuel tank will work for all of these various applications.

            However, electric buses often have to be more specialized. Different applications may require different battery capacities and charging systems. In many cases, bus manufacturers are learning to tailor electric bus systems to meet the needs of individual customers. This is what prompted Temsa to develop its own programmable electric bus rather than limiting options.

            The development of an electric bus at Temsa dates back a decade. Electric buses were relatively rare in those days, but Temsa was getting suggestions from customers, from the industry and even from their own staff. Electric buses were obviously the way of the future because they essentially eliminated any pollution at the operating end. Electric buses also had significant advantages in other areas because they were more economical to operate and maintain.

            Initial work started in 2010 when Temsa coordinated a European research project called EcoGem. It ran from September of 2010 to February of 2013 and had funding in excess of three million Euros. The research concentrated on fully electric vehicles and developed useful information including emphasis on electric power consumption. Since battery capacity was (and still is) limited, it was important to know the impact of various parameters on power consumption including traffic, weather conditions, use of heat and air conditioning, as well as waiting times during charging.

            As this project ended, Temsa felt they had enough information to move ahead with developing an electric bus. However, their original efforts in finding developmental partners and outsourcing components were disappointing. Several major companies with electric bus systems were contacted. Their systems typically were developed for specific brands or specific applications and were not well suited to Temsa’s idea of something more programmable. Attempts to locate electric bus components in 2013 were also disappointing. Automotive grade electric vehicle components and supplies were very limited at that time. Some of the early developmental prototypes used parts, connectors and cables from electric train part suppliers because bus equivalents were not readily available.

            At this point, Temsa made the decision to move ahead with developing its own electric bus. An application was made to The Scientific and Technological Research Council of Turkey for funding to develop a nine-meter (31-foot) electric transit bus. The project started in 2013 and slowly came together. The TM4 electric motors came from a part of Dana and were built in Canada. Batteries came from Liyuan New Energy in China. What resulted was a bus with a battery capacity of about 160 kwh and a range of about 120 kilometers or about 75 miles.

            This two-axle, three-door city bus was completed in 2016 and named the MD9 electriCITY model. It was first tested in Gaziantep in southern Turkey for a year. The first delivery was two units to the Turkish presidency. The next order came from Sweden and was for six buses.

            One of the reasons why electric buses cost twice as much as diesel buses is the price of the batteries. What Temsa discovered is that as much as 60 percent of the cost of an electric bus can be in the energy storage system. As a result, Temsa decided to produce its own energy pack as well as do the software and programming so that they could be very flexible to the needs of their customers. They designed their own battery management system, battery case and printed circuit boards. Temsa used Lithium Ion Cells from Envision (formerly AESC-Nissan). The resulting Temsa battery pack system had the flexibility of adjusting electric storage capacity from 60 kwh to 960 kwh.

            When the Temsa battery pack was added to the nine-meter bus, the storage capacity went up to 240 kwh and the range improved from 120 km to 350 km (about 215 miles). Temsa was also able to substantially reduce energy consumption with a “one pedal drive” system. What this means is that when the driver releases the throttle pedal, the bus goes into regenerative braking. This provides two advantages. One is that the energy to slow down the bus is turned back into electricity and is put back in the battery system. The second advantage is that this reduces the need to use the regular brakes, which in turn reduces costs and maintenance. The Temsa battery packs and battery management system is available under the Temsa Tech brand to other companies that can use it.

            With the success of the MD9 electriCITY model, Temsa customers asked the company to develop a full-size, 12-meter (39-40 foot) two-axle, three-door transit bus. To suit different customer needs, three different power capacity options are available: 240 kwh, 300 kwh and 360 kwh. In addition, Temsa offers two different models. The Avenue Electron model was fully developed by Temsa engineers and has a conventional plug-in charging option while the Avenue EV model offers a fast charging feature developed by Temsa and Aselsan engineers.

            Both of these buses are built to EU regulations for European markets and were first available in 2019. With these models, Temsa is targeting operations in France, Germany, Romania, Bulgaria, Serbia, Poland, Netherlands and Sweden. Both models are a little more than 100 inches wide. The Avenue Electron has a range of up to about 350 km (215 miles) while the quick-charge Avenue EV has a range of about 100 km (62 miles).

            The most recent Temsa electric bus project started in 2019. Temsa is taking their popular TS 45 45-foot intercity coach and offering it as an all-electric coach known as the TS 45E. Externally, the coach is very similar to the diesel TS 45 except that components are now all electric. Internally, the coach uses a similar electrical system that has been proven in previous Temsa electric buses. This includes the TM4 electric motor, lithium ion NMC (Nickel Manganese Cobalt) batteries, the one pedal drive with regenerative braking, and various Temsa programmable options.

            In order to make the coach more practical, the Temsa engineers are changing some of the design to better accommodate batteries while minimizing the impact on passenger space and amenities. For example, the size of the overhead parcel racks will be increased and are optionally available open or closed. The underfloor luggage space will also be increased about 30 percent. In addition, the production models will be redesigned including a new face.            

It is expected that the TS 45E will have a range of about 200 miles, making it practical for commuter operators as well as local charters and shuttles. It will have a different dash than the diesel buses including programmable gauges and the all-important state-of-charge gauge. A prototype has already been put on display and shown. It is expected that this model will undergo approximately a year of testing so that adjustments and improvements can be made prior to production. Temsa is expected to start taking orders for the TS 45E during the second half of 2021.   

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