When John Deere introduced its full-size all-electric, battery powered tractor in late 2016, it was likely the shape of things to come on many farms. It is brawny with 130 kW hours of battery capacity and an equivalent power output of 402 horsepower. It’s two 150 kW electric motors are simple and promise reduced maintenance, compared to a diesel power plant. And then there’s that instant torque!
The SESAM (Sustainable Energy Supply for Agricultural Machinery) tractor proved it could do many tough farming chores with only a whisper and no on-site emissions, but a limited duty cycle and an estimated 3-hour recharge for the stacks of batteries under the hood meant the one-off prototype was just that for today’s farm – unless a producer wanted to buy multiple expensive battery packs to swap several times a day during planting.
But what if that same tractor could be recharged 50-100% over a lunch hour? That could be pivotal in the adoption of all-electric traction power on farms across the world.
Tim Sherstyuk, chief commercial officer for GBatteries in Ottawa, Canada, says the “lunch hour recharge” is possible and could be easily attained with battery charging technology his 5-year-old startup firm is pioneering.
“We don’t make batteries and we don’t make chargers,” he explains. “Our technology is a mixture of hardware and software that falls between batteries and chargers. It allows us to monitor what is taking place inside Lithium Ion (Li-ion) batteries as they charge and adjust the charge to allow faster charges without damaging the battery.”
Sherstyuk says it’s possible to recharge cell phone or vehicle Li-ion batteries in as little as 5 minutes, but doing so with current charging methods increases heat and reduces cycle life of the battery from 600-800 down to 50 or fewer cycles.
“Consequently, manufacturers limit how quickly their batteries can be charged to remain viable over a reasonable battery life,” he says. “With our technology we can decrease the irreversible chemical changes inside the battery usually associated with fast charging rates and maintain long life cycles for Li-ion batteries.”
Most recharging procedures provide a constant direct-current charge to the discharged battery until the cell begins to reach its maximum charge. At that time, controllers begin to taper the intensity of the recharge current until the maximum charge has been attained.
Sherstyuk says research shows this method of Li-ion recharge actually damages the structure of the battery’s cathode, ultimately shortening the life of the battery.
“Think of the interior of a battery as a mesh sifting device through which you are trying to sift grains of rice,” he explains. “In our analogy lithium ions are the rice grains being pushed by electromotive force (voltage) through a forest-like mesh within the battery during charging.
“If you push rice through a mesh sifter, some grains will pass through, but many will pile up, impeding the flow of others through the mesh. The harder your push the rice the more resistance results,” he adds.
“The technology we’re using essentially shakes the sifter to allow a more even flow of rice (electrons) through the battery, thus enhancing the charging process and allowing faster charging rates without things breaking within the battery and causing permanent damage.”
Technology to “shake the sifter” has existed for years in the form of computer-controlled surge-charging, which alters the amplitude of the charge voltage and current, provides rest periods within the charging cycle and periodically reverses the charge to dislodge “stuck” ions reacting within the battery’s chemical composition. Research shows surge charging is of little value in a lead-acid battery, but in the case of Li-ion batteries, the procedure provides many benefits.
GBatteries is taking the potential of surge charging a step further by using computer-controlled surging (voltage and current changes, rest periods and current reversal) along with proprietary internal battery condition monitoring during the charging cycle.
“We monitor the chemical and current flow conditions within the battery on a real-time basis, and through the use of artificial intelligence capabilities and algorithms our research has provided, we can instantaneously alter the surge charging to meet the demands of the individual cell we are recharging. In some cases those changes can require less than a millisecond, giving us the ability to custom-charge the battery according to its individual needs.
“Our methods allow a 50% recharge of Li-ion battery cells within 5 minutes and a 100% recharge in 10 minutes,” Sherstyuk says. “Based on computer models and the overall ballistics of the Li-ion batteries in GM’s Chevy Bolt, we can now offer recharging of auto batteries within competitive times of an average fill-up of a tank of gasoline in conventional cars and trucks.”
Sherstyuk says the GBatteries technology is scalable and could easily be adapted to large battery packs such as would be necessary in farm tractors and other heavy equipment.
“It would be only a matter of scaling up the equipment necessary to handle the voltage and current necessary for the larger capacity batteries,” he says.
Given faster average charging times, engineers could begin designing vehicles with smaller battery packs, which adds to the incentive for further evolution away from internal combustion engines, Sherstyuk explains.
Currently, GBatteries is collaborating with several manufacturers of power tools and electric scooters, and in late April began working with a small electric automobile for on-site tests to apply the technology to recharging commercial battery packs made up of multiple Li-ion cells. The company also is in talks about the technology with the manufacturers of long-haul trucks.
On the farm, such technology conceivably would allow rapid recharge capability in any farm shop, or from a mobile auxiliary power unit, capable of 220 VAC – 480 VAC service.