EV-LITE - Advancing electric vehicle battery technology

EV Lite was a two-year Innovate-UK funded project starting in August 2012 which aimed to reduce the weight and cost of battery packs; a major barrier to the uptake of electric vehicles

ABOUT THIS PROJECT

The Manufacturing Technology Centre led the project and worked with a consortium comprising engineers and scientists from Loughborough University, Unipart, RDVS Components, the Bluebird Innovation Group and Cenex, the Government-backed centre of excellence for low carbon and battery technology.

The project team included the Aylesbury-based Centre for Remanufacturing and Re-use which is funded by Defra.

Canadian-based battery specialist Electrovaya supported the project and provided a Maya 300 low speed electric vehicle to act as a test bed. The Maya 300 is powered by Electrovaya’s lithium-ion super polymer battery.

The project’s objectives were to redesign a battery for an electric vehicle (EV) with the following attributes:

• Reduction in overall battery weight including structure, BMS, charging systems by 27% to 215kg, by reducing the weight of the non-cell elements of the battery by 50% from 144kg to 72Kg
• Reduce cost of battery structure, BMS, etc. by 50% from £9000 - £4500
• TAKT time requires automated assembly with one cell every 40 seconds, module time depending on size
• Consideration of 2nd and 3rd life as well as recycling.

The project consortium devised a battery specification based on the Bluebird EVX sports car whilst considering a flexible design to allow reconfiguration for other vehicles. A 4kw module was targeted running a 3parrallel 12series configuration operating at a nominal 40 volts, cooling was also specified as a requirement. For the Bluebird application 8 modules would be configured in series giving a 32kWhr vehicle. Bluebird completed vehicle design to provide much of the battery structure in load bearing chassis members to reduce component weight.

A battery was designed and manufactured utilising a novel design to minimise weight whilst improving assembly. The MTC designed and manufactured high current, push-fit connections, preventing the need for screwed or welded bus bars. The MTC also worked with RDVS to re-design the Battery Management Board (BMB) allowing it to be sandwiched between the cells and bus bars, removing the need for wiring. MTC and RDVS also designed and manufactured a novel Intelligent Battery Interface System (IBIS) which dramatically saved weight and assembly time of the standard device.

The Results

• The prototype battery achieved a weight of 38Kg per 4kw module, 36Kg for a module with an IBIS, therefore a weight saving of 41% was realised on the non-cell components resulting in a 45Kg weight saving at a 26.5 kWhr sized system level
• The cost of non-cell components was reduced from £9000 to an approximated £3396 (using volume supply chain) giving a cost saving of 63%
• A patent application has been submitted to protect 5 key inventions in the design.

The MTC built a robotic assembly demonstration cell and completed fully automated battery builds using a dummy battery. The build was completed in 18 minutes, 6 minutes shorter than the target TAKT time.