Lithium rechargeables Cycles = full dead to charged or does a topup = a cycle?

techwg

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I did a quick search but only found some info on nimh which I am not interested in. So if a lithium rechargeable 18650 battery shows data about charge cycles 100 the capacity is X, up to 200, 300 provides this other capacity etc, what constitutes a cycle? Is it only once you use up the battery and then charge it up from scratch? Or if I use 25% of the battery and top it up does that small topup classify as a whole cycle or would that classify as 25% of a cycle?
 

HKJ

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I did a quick search but only found some info on nimh which I am not interested in. So if a lithium rechargeable 18650 battery shows data about charge cycles 100 the capacity is X, up to 200, 300 provides this other capacity etc, what constitutes a cycle? Is it only once you use up the battery and then charge it up from scratch? Or if I use 25% of the battery and top it up does that small topup classify as a whole cycle or would that classify as 25% of a cycle?

A cycle is a full discharge and charge cycle, usual done at a fairly low current (0.2C). Higher current will reduce the cycle count.
 

Milan

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This can be found in official pdf files.
Example from Panasonic CGR18650CF:
【Test condition】
Charge :constant voltage/constant current, 4.2V, MAX.0.7It (1500mA) , 110mA cut-off
Discharge :constant current, 1.0It(2150mA), 3.0V cut-off
Charge / discharge rest time:20min.
Temperature :20℃
 
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