Two electric powered vehicles (EVs) from Optare which were on show at Coach & Bus Live 2013 demonstrated Optare’s position as the UK and Europe’s leading designer and manufacturer of full-size, commercially viable, battery-powered buses and its continued passion for innovation.
A 9.25 metre Solo EV presented in the ‘Showcase Arena’ is currently undertaking a series of demonstrations to operators around the UK. And on the company’s stand there was a 10.4 metre Versa EV, which is one of a number about to enter service with Nottingham City Council.
Both the Solo and Versa EV models are powered by the Magtec P144 zero emissions electric motor producing 150 kW of power and 2380 Nm of torque giving them swift and smooth acceleration and excellent hill climbing capabilities, as proven in service. A maximum speed of 95 kph (59 mph) can be comfortably achieved to ensure inconspicuous traffic compatibility.
The motor derives its power from two battery packs each consisting of 26 lithium iron, magnesium phosphate, maintenance-free batteries that provide a total of 333 volts DC nominal x 2 in parallel. This gives a daily range of between 110 and 150 kilometres (70-95 miles) on a single charge, depending on the duty cycle.
The range can be extended by the use of fast-charging technology on the bus, linked to charging points at the depot or at suitable points on the route, such as bus termini, and which allows for opportunity charging during layovers in the schedule. When in service the batteries also receive additional charging through the use of regenerative braking.
Normal charging is by means of two 7.5 kW integrated on-board chargers connected to a standard commercial three phase supply and which enables a full charge from zero, to be achieved in approximately six hours. An alternative is the optional 50kW off-board charger, which can provide fast-charging in around two hours, or opportunity charging as required. Later this year Optare plans to introduce an induction charging system as another option.
The drive motors, summation gearbox, chargers and battery packs are contained within a demountable frame, which enables rapid removal and uses ‘no loss’ couplings for fluid lines.
Although the initial purchase cost of an EV is higher than an equivalent diesel-engined bus, this is counteracted during the lifetime of the bus by savings of up to £8,000 a year on fuel alone, with daily recharging costs estimated at less than £10.00. Further savings result from significantly reduced maintenance costs because of the relative simplicity and robustness of the electric propulsion system and, in the UK, from the fact the EVs carry no Road Fund Licence cost.
In structural respects Optare’s EV products are the same as their standard diesel-engined equivalents. They feature an all-welded heavy-duty box section integral construction using a combination of stainless and high-grade carbon steel, backed up with an anti-rust protection system to ensure a long life. A combination of GFRP and aluminium modular exterior panels keep weight low and facilitates easier, cost effective repair or replacement.
Passenger ride comfort is assured by full air suspension with a ‘kneeling’ capability on the front axle that reduces the entrance step height when the air bags are exhausted. A manual fold-out ramp makes access easier and safer for passengers with reduced mobility, in wheelchairs or with baby buggies.