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What is Battery Cycle Life Test

Ni-CD battery and Ni-MH battery cycle life test in IEC standard as follow,

0.2CBatterydischarge to 1.0V,

a. 0.1C charge battery for 16 hours, then 0.2C discharge for two and half hours (first cycle);

b. 0.25C charge 3 hours and 10 minutes, then 0.25C discharge 2 hours and 20 minutes (2-48 cycles);

c. 0.25C charge 3 hours and 10 minutes, then 0.25C discharge to 1.0V (49th cycle);

d. 0.1C charge for 16 hours, delay one hour, 0.2C discharge to 1.0V (50th cycle).

For Ni-MH batteries, after 400 cycles according to above steps, its 0.2C discharge time should be more than 3 hours; for Ni-CD battery, after 500 cycles according above steps, 0.2C discharge time should more than 3 hours. In BYD, they also takes 1C cycle life test method, rated discharge, 1C charge 80 minutes, use V=20mV/pc control charge point, 1C discharge to 1.0V. After 500 cycles, capacity should above 60% of original capacity.

Cycle life test of lithium batteries stipulated by IEC as below: 1C constant current-constant voltage charge to 4.2V with cut-off current 20mA; delay 1 hours and then 0.2C discharge to 3.0V (one cycle), after 500 cycles, remaining battery capacity should be 60% of original capacity.