John Deere presented the first fully electric tractor, known as the SESAM (Sustainable Energy Supply for Agricultural Machinery), in 2016. The GridCON tractor looks very different to its predecessor, as it features no cab and no rows of batteries underneath the bonnet. It is the first vehicle to be fully electric, permanently cable powered and capable of fully autonomous operation in the field.
Based on a John Deere 6210R tractor, GridCON utilises a cable connection from the field border to the machine, which transfers power continuously at over 300kW. A 100kW electric motor powers the IVT transmission, and there is an additional outlet for implements powered by a 200kW electric motor.
A drum fixed to the tractor carries up to 1000m of cable, although the length can be extended if required. In the field, the cable is fed out and reeled in while guided by a robot arm to keep the operation friction free and at low load. An intelligent guidance system is also used to prevent the tractor running into or over the cable.
At work, the tractor follows preset rows fully autonomously at operating speeds of up to just over 12mph (20kph). The vehicle can also be guided manually using a remote control, which is particularly useful when manoeuvring the tractor to start work on field borders for example.
A power supply of 2.5kV AC is required, and the GridCON tractor uses a 700V DC bus for electric power distribution both onboard and for implements. The machine employs a cooling infrastructure for off-board electrical use, while total efficiency of the drivetrain is in the region of 85 per cent.
Total empty weight of the working prototype GridCON tractor including cable drum and robot arm is about 8.5 tonnes, so it is about the same weight as a conventional John Deere 6195R tractor but with twice as much power. Research engineers are aiming to reduce the weight further by at least one tonne.
Besides this favourable power to weight ratio, the concept offers the twin benefits of noiseless and emission-free operation. Compared to battery-powered tractors, the GridCON tractor also delivers around 50 per cent lower machine and operating costs.
