The 48V battery pack is a lead-carbon unit rather than the more conventional (and expensive) lithium ion unit. This battery tech is still in development but is said to be much more tolerant of extremes of temperatures than lithium ion.
Developed by UK company CPT, the ISG is said to be up to 80% more efficient than a conventional alternator and is designed to run in two directions – one to act as a charger and one to help drive the engine. Ricardo says it can “assist the engine” by adding 7.5kW (via the drive belt to the crankshaft pulley) to the engine’s output, and when it’s being used to slow the car via the engine, it can recharge “up to 12.5We” into the 48V battery.
Ricardo’s own figures show a monumental torque curve, peaking at around 221lb ft at just 1500rpm, with 110lb ft already on tap at just 750rpm. The standard 1.5 TDCi engine produces 199lb ft at 1750rpm.
The electric water pump is also an important link in the engineering chain. When cold, an engine’s fuel consumption is much higher, because cold oil means high levels of friction. A switchable electric pump – rather than a continuously driven mechanical pump – means coolant isn’t pumped around until the engine has reached operating temperature.
The most remarkable idea on Ricardo’s prototype is probably the Turbogenerator Integrated Gas Energy Recovery System (TIGERS) ‘e-turbine’, which sits in the exhaust stream and uses exhaust gas to drive a generator. Ricardo calculates that at motorway speeds, Tigers could recover around 1.4kW of energy to the battery.
So what’s it like on the road? Unusual, to say the least. One of the main philosophies behind the ADEPT Focus is ‘down-speeding’. Ricardo says running the engine at a lower speed – through longer gearing – reduces fuel consumption. Normally that would mean reduced acceleration, but ADEPT uses harvested waste energy to drive the electrically powered turbocharger, which then boosts performance.
On the roads around Shoreham, the ADEPT Focus felt somewhat slow and unresponsive, although much of that sensation was almost certainly due to the fact that the car was demanding I upshifted at lower engine speeds than seemed natural. After a while I became convinced that some form of automatic transmission would have been better suited to this drivetrain, because it would surely shift more quickly and at the optimum time.
Even so, in town driving it was fine, having enough low-speed acceleration to find gaps. It was on the wide open roads and long uphill drags that the ADEPT concept seemed to lack the traditional driveability drivers take for granted. Of course, the whole point of the concept is to reduce fuel use, so we can’t expect this car of the near future to offer breezy performance.