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EnerDel notes that batteries more quickly and efficiently adjust to load fluctuations than do traditional engine-driven generators. Shown is the MHPS-80 at the Battery Show. (Patrick Ponticel)

Enerdel goes off-road with its hard-carbon lithium-ion battery technology

At Smarter Shows' recent Battery Show in Novi, MI, EnerDel Inc. showcased two applications for its battery technologies.

One was its second-generation Mobile Hybrid Power System (MHPS), which was displayed at the show as a trailered power-generation system for a military ground applications. The company in May delivered the new MHPS to the U.S. Army Corps of Engineers’ Research and Development Center in Champaign, IL.

It offers a reduction in diesel fuel consumption of up to 70% “in most use cases as demonstrated by the military,” EnerDel Vice President of Engineering Sean Hendrix told Off-Highway Engineering.

The MHPS-80, as delivered to USACE-ERDC, features an onboard 15-kW charging generator, an 80-kW·h lithium-ion battery system, power inverter, and dc input for wind and solar energy. It is self-contained in a military-grade custom steel trailer, complete with two ABC fire extinguishers and automatic fire-suppression system in the battery compartment.

Operationally, the MHPS commands its onboard generator to recharge the lithium-ion battery in response to variable load demands. The stored energy from the battery system is then used as the main power source to the load. This architecture is “seamlessly” controlled by the MHPS and dramatically reduces generator runtime, diesel fuel consumption, and overall deterioration of the generator.

Another benefit is a reduction in noise generation by the generator—useful in many military scenarios.

While the unit shown at Battery Show “was designed with tactical military applications in mind, there are other applications beyond military,” Hendrix said. “You can paint this unit white and deploy it as part of a FEMA (Federal Emergency Management Agency) response to a disaster, or it could be deployed as part of rural electrification efforts in other countries or other regions of the world where electric grids are not available but there is a need to power loads like hospitals, schools, and clinics.”

The MHPS is highly scalable—20 to 120 kw·h, he added.

EnerDel in the week before the Battery Show announced formation of a strategic alliance with Ideal Power Inc. The battery maker will use Ideal’s 30-kW hybrid converter into a third-generation MHPS family of modular products and will provide even greater fuel-consumption benefits than the second-generation unit.

The basic building block of the 80-kW·h MHPS system is EnerDel’s 17.5-A·h energy cell. The company also makes a 16-a·h power cell. The cells originally were designed for an automobile application. Both are soft prismatic types of the same form factor and same NMC (nickel manganese cobalt) chemistry. The energy cell has 2C continuous and 3C pulse capability, compared to the power cell’s 5C continuous and 8C pulse. The difference is in electrode design and the number of electrode stacks (more and thinner electrodes, and hence more surface area and less internal resistance, for the power cell); there is also a slight change in the formulation, ”but for all practical purposes it’s the same chemistry,” said George Brutchen, EnerDel Senior Materials and Chemical Engineer.

He noted that EnerDel is one of few, and perhaps the only, company to use a “hard carbon” anode. Some of the advantages over soft carbon and graphite are higher power density, smaller cell volume changes during charge and discharge, and better low-temperature performance. Hard carbon is more expensive, however.

EnerDel also displayed at the Battery Show a new NiMH (nickel metal-hydride) replacement battery pack designed for hybrid-electric transit buses that use an Allison transmission. The fully integrated 19.6 kw·h battery system with 16-a·h soft prismatic cells “tops out at 720 V dc,” said Hendrix. It features a high-voltage disconnect unit, current monitoring, and full battery-management system. The turnkey system is a drop-in replacement that launches in the fourth quarter of 2014.

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