There are two types of Hybrid vehicle; Plug-in Hybrid Electric Vehicles (PHEV), such as the Golf GTE, this is where the high voltage battery can be charged via an external power source as well as by the vehicles own charging system, and Hybrid Electric Vehicles (or HEV), the Volkswagen Touareg hybrid falls into this category, this is where the vehicles high voltage battery is maintained by the vehicles own charging system and there is no external charging.
Currently this includes the Golf GTE, and is soon to include the Passat GTE. It offers the dynamics of a GTI alongside the sustainability of an e-vehicle. The GTE models are full hybrids with increased performance of a battery and an electric motor, with battery charging possible via a mains or charging point connection. They have both a combustion engine and a lithium-ion high-voltage battery driving an electric motor. On purely electric energy, they can travel up to 31 miles between charges and when electric and petrol combine the total range is up to 580 miles.
The car is fuelled by petrol with a standard petrol cap, alongside the plug in option behind the Volkswagen roundel on the front of the vehicle (Golf GTE). To charge the high-voltage battery with the standard mains charging cable, a standard mains socket can be utilised for around 3 hours 45 minutes. With an optional wall box or at a public charging station it takes 2 hours 15 minutes. A wall box has 55% high charger performance than a mains socket. Please note; there is no DC charge facility for Golf GTE.
The Lithium-ion high-voltage battery
E-vehicles and the Golf GTE have a 12V support battery, and are also fitted with a lithium-ion high-voltage battery. Lithium-ion high-voltage batteries are made up of several components. The robust exterior housing of the battery contains numerous modules, which are ordered differently inside the battery according to model or space. Each module consists of an array of interconnected battery cells. Electrical energy is stored in the battery cells developed especially for electric and hybrid vehicles. These cells contain a large electrical power supply and a high energy capacity. Energy is taken from the battery during driving and is made available to the electric motor. The electric motor recuperates during braking; this means that the battery is recharged using braking energy. During this entire process, a number of integrated safety systems and sensors are monitoring the cells, in particular their voltage and temperature.
The XL1 is the first diesel hybrid from Volkswagen, which offers a sustainable and efficient solution weighing just 795kg due to the large amounts of carbon fibre reinforced polymer (CFRP) that it is constructed with. It has a lithium-ion high-voltage battery in conjunction with a TDI combustion engine (800cc TDI two-cylinder common rail diesel engine), and is renowned for its ability to achieve 313mpg on a combined cycle. On purely electric energy it can travel up to 31 miles between charges depending on driving conditions, and when electricity and diesel is combined it can travel up to 310 miles depending on driving conditions.
The XL1 has a dual clutch gearbox to enable drive with both the e-motor and the TDI working together, and the e-motor working alone. Operating at 220V, the battery manages the flow of high voltage energy from and to the battery or e-motor and converts direct current to alternating current. The e-motor supports the TDI in acceleration or can work solely. For the e-motor to work unassisted, the TDI is decoupled from the drivetrain by disengaging a clutch, whilst the clutch on the gearbox side stays closed so the DSG is fully engaged with the electric motor. To restart the TDI the e-motor's rotor is sped up and coupled with the TDI clutch, accelerating the TDI to the required speed and starts it. During braking, the e-motor operates as a generator to utilise the braking energy to recharge the battery (battery regeneration).
The 800cc TDI has a cylinder spacing of 88mm, with a cylinder bore of 81mm and its stroke is 80.5mm. To reduce emissions, the 800cc TDI has specially formed piston recesses for multiple injection and individual orientation of the individual injection jets. The excellent, smooth running properties of the common rail engines were transferred to the two cylinder engine. Also, a balancer shaft that is driven by the crankshaft turning at the same speed optimises smooth engine running. The TDI’s aluminium crankcase was constructed to achieve high dimensional precision, which in turn leads to low friction losses. To further lower emissions, the XL1 employs the use of exhaust gas recirculation, an oxidation catalytic converter and a diesel particulate filter (DPF).
To charge, the AC/DC converter transforms the AC energy from the mains socket into DC energy, that is then fed through a cable into the battery.
Just 200 units were produced globally of the XL1. Production ended in 2015.