When storing the 18650, 21700 Li-ion batteries of your dive lights for a long time, it's better to partly charge them to around 3.6V or round 40-60% charge. This avoids full charging because high voltage makes the batteries more chemically active, leading to damaging reactions.
When a Li-ion battery gets fully charged, the voltage is at its maximum, which means a high amount of lithium ions have moved to the negative electrode. Over time, this high energy state can cause unwanted chemical reactions, leading to the degradation of the battery materials. It will reduce its capacity and lifespan.
Lower voltage, cooler temperatures help prevent battery wear. So for long-term storage, keep the batteries at a partial charge to reduce damage.
When a Li-ion battery gets fully charged, the voltage is at its maximum, which means a high amount of lithium ions have moved to the negative electrode. Over time, this high energy state can cause unwanted chemical reactions, leading to the degradation of the battery materials. It will reduce its capacity and lifespan.
Lower voltage, cooler temperatures help prevent battery wear. So for long-term storage, keep the batteries at a partial charge to reduce damage.