Archived posting to the Leica Users Group, 2012/05/20
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]I have dome some research into the life of rechargeable Li-ion Batteries. These are used in our M8 and M9 cameras ( and others I suspect). With Nicads, we were taught to allow them to fully discharge and then charge them up.. Not with Li-ion. In fact, these new batteries are a lot different than I thought..and how I was using them "Similar to a mechanical device that wears out faster with heavy use, so also does the depth of discharge (DoD) determine the cycle count. The smaller the depth of discharge, the longer the battery will last. If at all possible, avoid frequent full discharges and charge more often between uses. Partial discharge on Li-ion is fine; there is no memory and the battery does not need periodic full discharge cycles other than to calibrate the fuel gauge on a smart battery. " "Lithium-ion suffers stress when exposed to heat and kept at a high charge voltage." "The worst condition is keeping a fully charged battery at elevated temperatures, which is the case when running a laptop on the power grid. The pack does not die suddenly but will produce decreasing runtimes as part of aging. "Equally stressful is leaving a battery in a hot car, especially if exposed to the sun. When not in use, store the battery in a cool dry place. For long-term storage, manufacturers recommend a 40 percent charge. This allows for some self-discharge while still retaining sufficient charge to keep the protection circuit active. Finding the ideal state-of-charge is not easy; this would require a discharge unit with an appropriate cut-off. Users should not worry too much about the state-of-charge; a cool and dry place is more important. "Besides common aging, a Li-ion battery can also fail because of undercharge. This occurs if a Li-ion pack is stored in a discharged condition. Self-discharge gradually lowers the voltage of the already discharged battery The message: Charge your battery BEFORE it goes to zero. Best seems to be "daily" on a working trip / vacation. Store your battery in a cool place. I suspect a refrigerator is too humid. but maybe a plastic bag could get around this issue. Store when the battery is at less than 100% charge...but not fully discharged. Some of this also applies to Laptop use. Read the reference to find out more info... some of it is specific to the way Laptops are used... Reference: http://batteryuniversity.com/learn/article/how_to_prolong_lithium_based_batt eries Frank Filippone Red735i at earthlink.net