MEV R2 Electric Sport Car - Powered by LiFeBATT
Just like our battery systems, LiFeBATT Ltd is not your average battery company. The purpose of our Electric Sports Car project is to put our batteries where our mouth is! We will start by outlining the aims of the project and over the coming months you will be able to follow the progress, how we decided on the drive train and integrated our battery system. You will also have the opportunity to see and maybe even ride in the car at various events throughout the UK and Europe.
At the Northern meeting of the Battery Vehicle Society in February 2008, Stuart Mills of Mills Extreme Vehicles (MEV) and Ian Goodman (Managing Director of LiFeBATT Ltd) started talking about Stuart's new project, the R2, an open top two seater sports car of unique design. It was agreed, almost on the spot, that
We talked to several people in the US drag racing scene and ended up at the door of Steve Clunn at GrassRootsEV.com in Florida. With the help of Steve and George at Netgain motors, we decided on the following drive train:
Netgain WarP9 Series Wound DC Motor.
George undertook some data analysis, including the vehicle weight, tyre size, drag coefficient, voltage sag, max amps of the controller etc. and came up with 500ft lbs of torque at take off, 0 to 60 in 4.5 seconds, or thereabouts, and a top speed far in excess of anything that we are comfortable driving at.
Parts started arriving in early April, the first was the motor. The Netgain WarP9 is a bit of a beast, weighing in at 70kg, so the first job was to find a suitable gearbox to mate it too. We had previously agreed with MEV to retain the clutch in order to achieve quick gear changes, with third and fourth being used via a Linear Actuator to push/pull the gear linkage between gears. This would be activated from a switch or button on the steering wheel. The chassis was designed for Ford Focus donor parts, but although light, the gearbox was considered too weak for the torque provided by the WarP9. A quick chat with MEV and a few breakers yards confirmed that a Mondeo gearbox would be strong enough.
The battery modules arrived too. Their configuration may seem a bit odd, (15 X 24V 20Ah modules, five in series and three parallel strings) but this gives endless possibilities for installation and increasing power and range. Another parallel string at 20Ah could be added with 5 additional modules, or more power with three additional modules taking the system up to 144V. Also, as the battery system will last over 4,000 cycles (approx 120,000 miles) we would have the option of using this pack in other vehicles.
MEV crafted the adaptor plate and then installed the WarP9 to the transverse gearbox by mid April. We arrived for the first day of work to install the battery pack with a brief outline as to where everything was going to go. Stuart and his team made quick work of the simple battery trays, made from 50mm by 3mm thick aluminium angle. The battery modules were then secured to the tray with a ratchet strap. It is a very tight fit, if the modules had been 2mm bigger we would have had to rethink their installation completely. Because LiFeBATT cells do not vent or emit any noxious gases, they do not need to be enclosed. However, we do intend to fit rubber covers over them once the data cables have been connected. We also took the opportunity to layout where the rest of the parts will go and the supports that were required.
We returned the following week, just three days before the vehicles launch at the Stoneleigh Kit Car show to finish the drive train installation. We put the main contactor and reverseing contactor into a waterproof enclosure at the very back right of the motor bay, secured to a sheet of 3mm aluminium, which in turn is secured to the rear chassis. Also on the aluminium sheet we mounted the LogiSystem controller, in the hope that this would act as a sufficent heat sink. There isn't a lot of air moving about in the back so we intend to monitor the controllers external temperature during testing and adjust it's position or add cooling as required.
On the 29th April 2008 at 8.04pm, after working for 11 hours straight, the LiFeBATT powered MEV R2 turned it's wheels under electric power. The throttle ramp and max Amps on the controllers were turned down to their minimum settings. We drove up and down a deserted road until our hands and face were frozen! Top speed was only about 30mph as the gearbox was stuck in either first or second; More on this later. Acceleration appeared brisk and according to the data logger we only pulled 341Amps. Also, the throttle ramp was at it's lowest setting so we were all very hopeful for future performance.
On Sunday 4th May 2008 we unveiled the R2 at The National Kit Car Show at Stoneleigh. Stuart trailered the R2 to the event and drove it around the exhibition hall to his stand, which attracted lots of bewildered looks from the petrol heads. The event was the perfect place to show an electric sports car and attracted a huge amount of attention.