If you've ever driven on a highway, then you've seen giant 18 wheel Class 8 heavy duty trucks, the behemoths of the road. While today, the majority of Class 8 trucks primarily use diesel fuel for power, the future is likely to bring hybrids that incorporate into their designs more than one way to power the truck. And one of the biggest factors in garnering widespread acceptance for 'series hybrid' powered Class 8 heavy duty trucks is utilizing a battery that fits the truck's unique needs.

On average, Class 8 trucks are driven 100,000 miles plus annually..This makes them a great candidate for even moderate fuel-savings. Incorporating a series hybrid drive train into a truck rebuild is one way to accomplish this, as explained in a recent SAE article.However, the series design requires a more advanced battery technology than what is currently being used in the Class 8 truck market. That's because the batteries in a Class 8 heavy duty truck need to provide ample power when called on and then the batteries need to recharge quickly without creating excessive heat and the problems accompanying that heat creation. The batteries need to be able to take advantage of regenerative braking opportunities while providing enough peak power to the motor to allow the motor and generator to run at a constant speed, thus creating a consistent fuel burn amount - which results in significant fuel savings.

While many fuel savings solutions have been tried in recent years, success has been elusive because of available technology and because of a cost to benefit ratio that makes economic sense. One solution that is proving to be an exception is the series hybrid approach that is currently being implemented in early truck conversions by ePower Engines. Standard engine parts, combined with a proprietary vector drive system and a unique battery chemistry (that includes an extremely high rate of charge acceptance; a rapid charge-discharge cycle; long cycle life; etc.) have resulted in some surprisingly good fuel economy numbers. After spending a couple of years experimenting with battery chemistries that didn't work for one reason or another, ePower has incorporated Axion's PbC batteriesinto their final design, and have been running road tests with those batteries for the last 12 months.According to author Karen Boman at Rigzone, "When a truck needs extra power to pass or go up a hill, it can draw on the battery to provide a boost power system to supplement the gen-set power versus dramatically and quickly increasing diesel fuel" use to provide that power. In addition, the PbC batteries are very well positioned to take full advantage of regenerative braking opportunities.

The SAE article further explains that batteries, incorporated into series hybrid designs for heavy duty trucks, will be required to provide both power generation - similar to a supercapacitor, and energy storage - similar to a battery's properties. So Boman's point is an important one - "The hybrid battery technology supplied by Axion has super capacitor-like qualities in one half of the battery; the other half has storage qualities." Just what the Doctor ordered!

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