I see the same Aviation Week article says that the batteries will be "... subjected to repeated load tests of 18 kw over periods of 40-45 sec. ...". This looks like the same test originally specified in the Boeing Control Specification Document (SCD) for the battery.
http://www.pprune.org/7745740-post1009.html
The NTSB Interim Factual Report dated March 7, 2013, quoting the manufacturer, said that the operating range of this battery is 20V - 32.2V, with a "nominal voltage" of 29.6V. At this "nominal voltage", 18kW requires 608A from the Yuasa cells whose published current maximum is 375A.
Does anyone know what factor dictates this 375A limit?
Adding to the confusion, the NTSB "MATERIALS LABORATORY FACTUAL REPORT", Report No. 13-013, February 19, 2013, says on page 8-9: "Based on information from the battery manufacturer", nominal specifications for the individual battery cells include a "Maximum discharge capacity" of approximately 1000 A (though typically 450 A for ~45 seconds, when being used for APU start-up, and no greater than three attempts at start up), which is rather different from the published specification for the individual cells of 375A. And on page 4, for the contactor which is inside the battery case, "The battery design incorporates a contactor rated to 400 A", which is a lot less than the 1,000A now claimed as the battery maximum discharge capacity.