A number of the major asphalt compactor manufacturers now offer compact machines that feature electric power. These machines are all compact units that are aimed at customers in segments such as the rental sector. Compact ride-on twin drum compactors are used widely in road construction operations, particularly for smaller works and for repairs following utilities works. Rental machines typically may spend a lot of time standing waiting to be used rather than operating continuously, as with larger pieces of equipment.
Diesel machines are typically left idling while the asphalt is raked into position. After compaction, the machines travel to the next repair site where they may also be left idling for extended periods, wasting costly fuel. But battery equipment does not have to idle and will draw no current at rest. And with onsite utilisation times comparatively low, electric power offers a practical alternative for this equipment segment over conventional diesel engines.
While the purchase prices of electric machines are typically higher than for diesel units due to the cost of the batteries, running costs and maintenance needs are much lower. For the rental firms, eliminating the need for regular checks of engine oil and coolant levels or for the replacement of filters can simplify fleet management significantly.
In addition, electric compactor models are quieter than conventional diesel units, which is of extra benefit for use in urban areas or for night working where there may be concerns over noise levels. Electric machines also have no tailpipe emissions, a key factor for their use in towns and cities in Europe, California or China where restrictions are becoming increasingly stringent. These units also suit duties for use in enclosed parking areas or tunnelling applications where diesel exhaust would require costly ventilation.
Ammann is now offering an electric drive version of its 2.6tonne class twin drum roller, the ARX26e. This features the same compaction forces and drum dimensions as the standard ARX26 model, as well as the same control systems and operator station.
The machine can operate for a full shift on a single charge. It can be fast-charged using a three-phase supply or by a standard single-phase, 16A supply although the latter takes longer. The electric drive to the drum is direct and without hydrostatics, unlike some competing designs, optimising efficiency. The steering is conventional, using a hydraulic ram.
It is now some years since BOMAG first unveiled a prototype electric compactor aimed at the rental segment and the firm has subsequently introduced models to its range. The firm now offers two electric compactor models, the BW 100 AD E-5 and BW 120 AD E-5, for the 1m-wide and 1.2m-wide drum classes. The BW 100 AD E-5 weighs 2.5tonnes while the BW 120 AD E-5 weighs 2.6tonnes. Both have Li-Ion battery technology rated at 48V and 25kWh, with two high-efficiency electric motors that control the drum vibration and travel/steering independently, so only one motor is needed for travel mode to conserve power. the BW 120 AD e-5 offers a 65/60Hz drum frequency and 0.5mm amplitude. Compaction performance for both BOMAG models is said to be comparable with the equivalent diesel variants.
From Dynapac come the twin drum CC900 e and CC1000 e models, which are said to deliver the same power and performance as the conventional diesel machines. Both are said to offer savings on running costs, featuring fewer moving parts and low maintenance needs. The batteries are said to be able to manage a full day of operation without the need for recharging. The CC900 e and CC1000 e deliver the same static linear load, amplitude, gradeability, and travel speed as the diesel-powered models on which they are based, with no compromise on productivity or jobsite performance.
In a typical working day, a 1.6tonne roller will be used for repairs and compaction of around 70–80tonnes of asphalt/day at a layer thickness of 40–50mm, covering an area of around 700m2. According to Dynapac, this allows the battery to last for a full shift. In 90% of the cases in trials, about 20-30% of the battery level was left at the end of a shift.
With the fast charger, 400V/three-phase system it takes 1.3 hours to reach 80% charging level. The 230V/single-phase charger needs 6 hours to reach 80% of capacity. Dynapac is planning to provide adapters allowing the use of automotive charging stations.
Hamm is introducing a range of eight compact tandem rollers featuring electric drives. The firm’s new HD CompactLine models will all be offered with the option of electric power instead of the conventional diesel engines.
There are 24 models in the conventional CompactLine at present, with weights ranging from 1.6tonnes up to 4.8tonnes as well as drum widths from 800-1,380mm and an array of specifications and features. Hamm is now offering emissions-free electric variants of the most popular units.
The new electric models feature Li-ion batteries with 23kWh capacity, allowing operation for a full working day without the need to recharge. Included in the electric range is a model featuring both oscillation and vibration, the first such model available on the market. This unit will be of particular benefit for working in urban areas as it is quiet in operation while the oscillation system means it does not transmit vibration to the surrounding area.
Volvo CE is introducing its 0025 Electric compactor, the first of the firm’s new electric machines designed specifically for the asphalt industry.
The electric driveline of the 0025 Electric is based upon the same proven architecture and components found on Volvo CE's ECR25 Electric compact excavator and L25 Electric compact wheeled loader.
The zero emissions performance suits the machine for use in sensitive or urban environments with strict emission regulations.
Expected to operate for a full shift on a single charge depending upon the type of job and intensity of the work cycle, the 0025 Electric has the same charging solutions as its forerunners the ECR25 Electric and L25 Electric. Customers can choose the right solution depending on operational requirements. The machine comes with an integrated onboard charger which enables charging from 0 to 100% in as little as three hours depending on AC power level. With an optional offboard DC fast charger this can be achieved in little over an hour.
Combining the proven Volvo Asphalt Compactor platform with battery power, the 0025 Electric offers 24kW of available power, 30% more than the conventional Volvo 0025B. The result is a more responsive machine in terms of speed and vibrations, which performs better on grade. It also works better at high altitudes compared to a diesel machine.