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SAE EV ENERGY UPDATE

THE SAE 2013 Hybrid & Electric Vehicle Technologies Symposium, held February 19-21 in Anaheim, devoted several sessions to batteries and other onboard energy storage. Discussed were the contrasting needs of conventional hybrids (HEVs), through plug-ins (PHEVs) to battery electrics (BEVs) and beyond to fuel-cell vehicles (FCEVs).

SAE2013Hybrid

Increased electrification from HEV to PHEV to BEV evidently requires more on-board energy. (See www.wp.me/p2ETap-wU for a Glossary summarizing these aspects.)

An interesting point: Battery packs need to be oversized to account for performance degradation below or above temperate climes and beyond 5 years in use.

EVs

BEV batteries are inherently challenged by cold temperatures, just as they are by hot weather.

Dr. Menahem Anderman, Advanced Automotive Batteries, identified three significant challenges in automotive battery design: crash protection, overcharge protection and precluding a “soft” electrical short from turning into one that’s catastrophic.

Anderman also noted that today’s battery cost analyses are complicated by a current instability of the business. There has been excess capacity—and more than a few bankruptcies.

He and other SAE presenters offered cost estimates of lithium-ion battery packs ranging from $2000-$4000 for HEVs, to $6000-$10,000 for PHEVs and more than $12,000 for EVs.

Battery specialists at the symposium predicted cell costs in the region of $300-$400/kWh in 5-10 years, as compared with $500-$800 today. One suggested $250/kWh by 2025. When asked about $125, he and others agreed, “Never.”

The

The 20-kWh battery pack of the 2014 Chevrolet Spark BEV contains 336 lithium-ion cells in several modules.

Specific costs, of course, depend upon what’s being discussed: battery cells, modules or complete packs. An interesting point: Cells inherently have a more steeply descending cost curve. It’s more difficult to find cost reductions in the cells’ assembly into modules and, especially, modules configured into complete packs.

Specialists linked these cell/module/pack distinctions with Boeing’s recent problems concerning lithium-ion battery packs on its 787 Dreamliners. It was generally agreed that a solution lies in optimal battery management systems and pack designs.

A fundamental question: Will battery manufacturing be an automakers’ business or will suppliers handle it? Specialists recognize that the larger automakers have already assumed design and development of all aspects of electrification: motors, power electronics—and batteries, from cell technology to final pack design. Smaller automakers will continue to depend on a supplier network.

Jesse Schneider is manager of development for EVs, fuel cells and standards at BMW North America. One of his symposium presentations focused on this last area, SAE standards, particularly for wireless charging of EVs.

The idea of passive charging is seen as a game-changer in EV acceptance: Drive into your garage—or an appropriate EV parking space—and leave recharging to automatic control. Similar technology already exists for recharging mobile phones and the like.

The process uses resonance inductance. An electrical current induces a magnetic field—and vice versa. Electrical energy can be sent wirelessly from one device to another if the second field is tuned to resonate with the first.

Inductive charging has been around for years (GM’s EV1 had an inductive paddle, not a conventional receptacle, for recharging). Improvements in efficiency have generated the latest interest. One goal is a recharge efficiency greater than 90 percent. Another is reducing the alignment sensitivity to permit park-and-recharge, with nothing on the driver’s part other than placing the car over the charging pad.

With this comes a need for standardization in choices of frequency, communications or “handshake” protocol, common operability around the world—and safety.

An object-detection default is an essential feature. Any ferrous material on the charging pad would get hot during the charge process. The neighbor’s cat could be attracted to the warm surface.

European inductive charging, above, has focused on front-mounted car hardware. By contrast, Japanese practice, below, favors rearward location.

European inductive charging, above, has focused on front-mounted car hardware. Japanese practice, below, favors rearward location.

LeafInductive

Standardization comes just in time: At this point, Germany’s wireless charging puts the charging-pad interface toward the front of the car; Japan’s, toward the rear.

Guidelines published this year are expected to evolve into SAE Standard J2954 by 2015. ds

© Dennis Simanaitis, SimanaitisSays.com, 2013

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