E-Mobility Engineering 019 | In conversation: Stephen Lambert l WAE EVR l Battery case materials focus l Quality control insight l Clipper Automotive Clipper Cab digest l Optimising battery chemistries insight l Powertrain testing focus

56 May/June 2023 | E-Mobility Engineering Future capacity boost However, the company commissioned some analysis to see howmuch capacity could be packed into the available volume. “We asked some battery specialists to look at the space in the cab and what sort of capacity we could create with the VDA 355 modules we are planning to use when we get into higher production volumes,” Medwell says. “We can probably fit about 57 kWh in the present battery boxes. That is when we start to achieve ranges of 180 to 200 miles, which will be near-perfect for cab drivers.” While the front battery box is in the taxi’s engine compartment, the other at the rear is in the boot/trunk. However, Medwell points out that luggage normally rides in the cabin with the passengers, while the boot is home to the spare wheel, a few tools and so. In the Clipper Cab, the spare wheel has therefore been moved to under the floor where the fuel tank used to be, and the use of VDA battery modules will allow the company to free up some extra space in the boot by reducing the height of the rear battery box. That though is not a major concern. “It is not the ‘be all and end all’ for taxi drivers, as a lot of them don’t really use that rear space anyway,” Medwell says. Finding space for components the vehicle manufacturer never intended to install is always a challenge in any conversion. But, says Medwell, “The benefit with things like the motors and inverters is that they are small compared to an engine. Where we have mounted the motor, it can sit really low down and quite far back. It is still in the front compartment, but it’s almost where the gearbox used to be. “That just leaves the task of trying to find space to get as much battery capacity in as possible. It is always trickier when the car is not designed to be an EV, you don’t have all that space in the floor you get with a skateboard chassis.” Repurposed heat exchangers Leaf batteries are passively air-cooled, so the Clipper Cab retains this system for its split pack. The rest of the thermal management system is also standard TX4 equipment, some of which is repurposed, and all the equipment is under the cab’s bonnet. The main radiator for the diesel engine has been removed, but the smaller cooler for the now-absent automatic transmission is still in place and cools the onboard charger, the DC-DC converter, the motor and the inverter; the original condenser for the air conditioning also remains. Airflow over all these heat exchanges is aided by the cab’s original electrically driven cooling fan, providing plenty of spare capacity for hot days. The 12 V battery that runs the cab’s original electrics is used to open and close the HV contactors in the main battery pack as well as running the TX4’s original electrics. Nissan gearbox mods Clipper alsomade a foray intomechanical engineering, modifying the Leaf’s direct- drive gearbox used in place of the TX4’s large automatic transmission. Medwell explains, “Most EV retrofitters keep the car’s existing gearbox and connect the electricmotor to it, but because the taxi had a huge automatic gearbox it would have been quite complicated to dive into that. So we decided to get rid of it and use the one from the Leaf. That involved removing the differential from the gearbox, and cutting a hole in the casing so that the drive could be taken from the second of three cogs that provide the donor Initially, a single charge should provide a range of 120 miles in city use, and 40-50 miles can be added in about 20 minutes on a fast charger The rear battery box of the split pack lives in the luggage compartment, which is not an issue for taxi drivers as luggage tends to travel in the cabin with passengers (Author’s photo)