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Greatest Volume and Accuracy


05/23/2011 1:00PM

The largest and most-accurate device of its kind, the LVBC can determine the exact amount of heat generated by battery cells, modules, sub-packs, and even some full-size packs as they are charged and discharged. It combines a high volume test chamber and wide temperature range options with state-of-the-art thermal isolation and control, current load capabilities, and precision measurement.

In addition, the LVBC is the only calorimeter designed to test the liquid-cooled batteries found in the Ford Electric Focus, the Chevy Volt, and the Tesla Roadster. GM used an earlier NREL calorimeter to help create the Volt battery.

"We knew there was a need for this technology. Testing cells and smaller modules in lower-capacity calorimeters was only giving usand car and battery manufacturerspart of the picture," said NREL senior engineer Matthew Keyser, who developed the LVBC.

Despite the LVBC's large size, its heat-flux measurements are extremely precise, recording heat rates as low as 15 milliwatts and heat inputs as low as 15 Joulesabout the amount of energy released while rubbing your hands together. Achieving this degree of sensitivity in such a large volume required a number of design innovations, including superior thermal isolation and the ability to test batteries under realistic driving conditions. The instrument is able to determine heat levels, and energy efficiency within plus or minus 2 percent of actual values.