Battery Abuse Tolerance 145 Figure 3 Typical HPPC charge/discharge testing cycle. FreedomCAR Program Electrochemical Energy Storage Team (2003). From this testing, a mountain of additional data becomes available, including the resistance as a function of the depth of discharge, the pulse power capability, the amount of energy avail- able at different depth of discharge, the available power at different depth of discharges, how much power and energy fade the battery will experience over its life, the maximum and minimum depth of discharge values the battery is capable of achieving and still meeting the performance requirements, and the amount of heat generated during operation.
Additional characterization testing that may be included in your test plan may include: Self-discharge tests—help the battery designer to determine how much energy is lost over time as the battery sits in storage. Cold-cranking tests—show how much power the battery can provide at low temperatures to “crank” the vehicles engine and restart it. Thermal performance testing—describes how much power and energy are available at different temperatures. Energy efficiency test—describes the “round trip energy efficiency” of a battery cell or system. In essence, this tells us how efficient the overall system design is and how much energy is lost during use.
Cycle life testing—determines how many full charge/discharge cycles at a predefined set of operating conditions a battery will achieve. Calendar life testing—as it is unrealistic to actually test a battery for its full expected life, which could be 10–15 years or more, it is important to get some idea of how long in calendar years the battery will last. That is exactly the purpose of this test (FreedomCAR Program Electrochemical Energy Storage Team, 2003).