Boosting Battery Life
Usually, a combination of several factors increases or decreased battery life. For increased cycle life
Use partial-discharge cycles
Using only 20% or 30% of the battery capacity before recharging will extend cycle life considerably. As a general rule, 5 to 10 shallow discharge cycles are equal to one full discharge cycle. Although partial-discharge cycles can number in the thousands, keeping the battery in a fully charged state also shortens battery life. Full discharge cycles (down to 2.5 V or 3 V, depending on chemistry) should be avoided if possible.
Avoid charging to 100% capacity
Selecting a lower float voltage can do t is. Reducing the float voltage will increase cycle life and service life at the expense of reduced battery capacity. A 100-mV to 300-mV drop in float voltage can increase cycle life from two to five times or more. Li-ion cobalt chemistries are more sensitive to a higher float voltage than other chemistries. Li-ion phosphate cells typically have a lower float voltage than the more common Li-ion batteries.
Select the correct charge termination method
Selecting a charger that uses minimum charge-current termination (C/10 or C/x) can also extend battery life by not charging to 100% capacity. For example, ending a charge cycle when the current drops to C/5 is similar to reducing the float voltage to 4.1 V. In both instances, the battery is only harged to approximately 85% of capacity, which is an important factor in battery life.
Limit the battery temperature
Limiting battery-temperature extremes extends battery life, especially prohibiting charging below 0?C. Charging below 0?C promotes metal plating at the battery anode, which can develop into an internal short, producing heat and making the battery unstable and unsafe. Many battery chargers have provisions for measuring battery temperature to assure charging does not occur at temperature extremes.
Avoid high charge and discharge currents
High charge and discharge currents reduce cycle life. Some chemistries are more suited for higher currents such as Li-ion manganese and Li-ion phosphate. High currents place excessive stress on the battery.
Avoid very deep discharges (below 2 V or 2.5 V)
Very deep discharges will quickly, permanently damage a Li-ion battery. Internal metal plating can occur causing a short circuit, making the battery unusable and unsafe. Most Li-ion batteries have protection circuitry within their battery packs that open the battery connection if the battery voltage is less than 2.5 V or exceeds 4.3 V, or if the battery current exceeds a predefined threshold level when charging or discharging.