Using battery power makes operating the lift virtually noiseless.
Its only sound is the quiet buzz of the hydraulic pump that raises, lowers and swings the two-piece, 55-foot articulating boom used for lifting power-company technicians to work in high places.
The aerial lift, itself, is the same Terex unit used throughout We Energies’ fleet of service trucks to lift workers up to power lines, transformers, fuse lines, and other elevated work sites.
The difference is in how the power to run it is provided.
Quiet Battery Replaces Running Diesel
On a normal service truck, the aerial lift’s hydraulic system is driven by a power-take-off (PTO) that is driven by the truck’s diesel engine.
That means the truck’s engine has to stay running while the truck stands still. The crew uses the lift to work on high-up power lines, transformers and other electrical equipment.
Running the engine makes noise, eats fuel and creates exhaust.
The aim of driving the aerial lift by battery is to make the operation quieter and more ecologically friendly by enabling the truck’s diesel engine to stay turned off while the crew works.
When the lift is working on battery power, all you hear is the quiet buzz of the hydraulic pump that powers its movement.The battery set, which weighs between 3,500 and 4,000 pounds, mounts beneath the truck. It can be recharged overnight by plugging into a 240-volt 3-phase power source in the shop, or by a power take-off driven by the truck’s diesel engine. Being able to operate the lift without running the engine saves fuel and also eliminates the exhaust that would normally be produced as the diesel engine ran the PTO to power the lift.
The massive, approximately 4,000-pound battery set mounted beneath the service truck’s chassis stores enough electricity to power the aerial lift for up to 10 hours, according to We Energies Electric Operations Supervisor Dave Effertz.
The battery system can also run the safety beacons and provide heating and air conditioning for the truck cab.
A digital display in the truck’s dashboard tells the crew about the batteries’ output and how much charge is left in them.
The battery set can be recharged by plugging into a 240-volt source overnight (when electricity is cheaper), or by the truck’s diesel engine during travel between work sites.
In case the battery set runs too low on energy to operate the aerial lift, the system is set up so the lift can also be powered by the truck’s diesel engine in the conventional way.
The system’s ability to operate on either type of power led its developer, Dueco (Dalum’s Utility Equipment Company, Inc., Waukesha, WI), to name it "Hybrid."
Thorough, Exacting Test Measures Several Results
Since December of 2008, We Energies Waukesha service center has been conducting a thorough test to see how well the Hybrid power system works and how it stacks up economically and ecologically with the standard PTO-driven aerial-lift systems now standard in its fleet.
Supervisor Dave Effertz says, "We want to make this test as accurate and thorough as we can. The decisions we make from it could affect the direction we go in equipping our service trucks for many years to come, so we want the best and most complete information we can get."
The key questions, says Effertz, are ‘Does the system perform at least as well as the one we’re using now?’ ‘Does it make economic sense?’ And ‘Does it help ecologically?’
To make an accurate comparison, Effertz team identified four trucks in its fleet that matched the Hybrid test truck as closely as possible in all respects from model, weight, engine, transmission, and other specifications to age, mileage, work hours, and other vital considerations.
Since December, We Energies’ service crews have been operating all four trucks as identically as possible and recording essential data like miles traveled, fuel used, hours worked, amount of time for lift operation, kind of weather worked in, service requirements, tire life, and so on.
"The idea," says Effertz, "is to see every way that the battery system affects the truck and aerial lift’s performance."
As far as the aerial lift is concerned, Effertz confirms there has been no difference. "Operators tell me that the speed, reach, lifting capacity, and responsiveness of the lift are exactly the same whether the power comes from the PTO or the battery set," he says. "We used it in some of the coldest weather of the winter, and the batteries still supplied plenty of power and working time."
One big difference, notes Effertz, is that the person in the bucket and the crew on the ground can easily talk to each other, which makes communication much easier and working much safer.
The data on truck performance is still being gathered, but Effertz says that, so far, it looks promising, too.
When the test with this system is done, We Energies will conduct a similar test with a different battery-powered system currently being developed by truck manufacturer International.
In the end, We Energies will evaluate both systems’ initial cost, operating cost, system life, reliability, productivity, and ecological impact, then decide whether to purchase either of the systems.