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

May/June 2023 | E-Mobility Engineering 53 Proof of concept At the moment there are three Clipper Cabs in existence. The first is based on an older TX2 with the diesel powertrain removed and the chassis fitted with components stripped out of an E-NV van. It uses everything from the battery, ECU, inverter and motor to the throttle pedal, steering column and windscreen wiper motors. The result is a proof- of-concept vehicle that moved under its own power well enough to obtain funding from the UK government’s Niche Vehicle Manufacture scheme. “Once we had proved we can do it, we changed tack a little,” Medwell says. “We went down the open inverter route, which allowed us to modify the Nissan motors and develop our own ECU.” The open inverter concept began as a project focused on a scratch-built inverter and ECU hardware using open standards, but has since shifted to using open ECUs to control OEM inverters, including over a CAN bus system. The company then built twomore vehicles to the revised specification, whichMedwell describes as production- ready prototypes based on the TX4. Over the past 7months, they have been driven the length of the UK by Clipper staff, who used the opportunity to canvass local authorities to find out what the company needs to do to be able to license the vehicles as taxis in their jurisdictions. “Usually it’s things like age limits, so we are trying to convince them that, as this is a zero-emissions vehicle, age limit might not apply,” Medwell says. Taxi cabs as well as private hire vehicles are subject to a 12-year age limit, after which they have to be replaced with cleaner vehicles. The rule prevents drivers from buying second- hand EVs, although they can still buy new diesels. Some local authorities are dropping the age limits and switching to emissions limits for diesels and/or annual or six-monthly condition inspections. Type approval and IVA As the Clipper Cab is a conversion of an existing type-approved vehicle, there are limits to the modifications that can be made without voiding the approval, with critical components and systems including the chassis, brakes and steering in particular being tightly controlled. The regulations set out a points system to rate modifications, and a score of more than eight voids the type approval, Medwell says. “We therefore make sure we don’t drill any holes in the chassis, we don’t touch the braking system or the steering system, and we attach for the cab, although that takes place after purchase from the breaker, fromwhom there may not be much comeback. The financial risk, however, is small because a good used Leaf motor can be obtained for under £1000 and an inverter for around £200 – a small proportion of the £8000-9000 cost of a written-off Leaf, the bulk of its value being in the battery. While the second-hand ethos is quite eco-friendly, it is as much about developing the proof-of-concept vehicle, early prototypes and small- scale production, although the policy is likely to change to cope with larger production quantities, Medwell says. “We will definitely keep to it though for the first 13 months and the first 10-20 cabs. When we are looking at hundreds of cabs, that is when we will start looking elsewhere.” Electrified TX4 on test last year. The rectangular panel in the grill pivots to reveal the charging socket (Images courtesy of Clipper Automotive unless stated otherwise) Digest | Clipper Automotive Clipper Cab The Nissan Leaf/E-NV inverter is controlled by a new ECU of Clipper’s own design and drives the standard Nissan electric motor, which is tuned for maximum range