Quote:
Originally Posted by frankz
I'd love to see where you've seen that reported for Lithium Ion batteries, as the recommended storage charge level (where the charge level has the least effect on the life of the battery) for Lithium Ion batteries is 40%.
At a 40% charge at 25 degrees C, your battery will naturally lose 4% of its capacity in a year. At 100% charge at the same temperature, it will lose five times that (20%).
http://batteryuniversity.com/learn/a...ased_batteries
Lithium Ion Polymer battery manufacturers recommend discharging the battery to 50% for storage purposes. That doesn't sound anything like "never letting it get discharge 50%." You're intentionally discharging it to that level with the understanding that it will slowly discharge in storage.
http://en.wikipedia.org/wiki/Lithium...olymer_battery |
Hmm, did you even read that
first article you linked too? Apparently not. Here is what it said:
Quote:
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. If full discharges cannot be avoided, try utilizing a larger battery. 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.
Table 2 compares the number of discharge/charge cycles a battery can deliver at various DoD levels before lithium-ion is worn out. We assume end of life when the battery capacity drops to 70 percent. This is an arbitrary threshold that is application based.
A partial discharge reduces stress and prolongs battery life. Elevated temperature and high currents also affect cycle life.
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The article then gives a table showing the battery life expectancy (cycle life, or number of charges the battery can expect to have before it dies) based on the Depth of Discharge (DoD, how far discharged the battery was before being recharged). The table clearly shows that if you routinely allow the battery to fully discharge before recharging, that is allow a 100% DoD, it will last about 500 recharges. If you routinely allow the battery to half discharge before recharging, that is allow a 50% DoD, it will last about 1500 recharges.