Pulled this off a site. After searching several site there were so many that went against the previous one. One would say one thing and the next would say another. But this is the one common thing among them all.
"Rather, to condition a new Li-ion battery, fully charge it; it should be allowed to charge for 7-8 hours on the first, initial charge. In other words, when you get your new cell phone - and it has a Li-ion battery - allow it to charge for 7-8 hours even if the cell phone claims to be fully charged. (It is preferable to use outlet charger vs car charger or USB charging via computer because of the voltage difference.) After that, there is no reconditioning necessary for Li-ion batteries since they don't suffer from the "memory effect". However, be sure to avoid fully draining/discharging the Li-ion battery as much as possible; every time a Li-ion battery is fully discharged, it loses battery power and life. (That doesn't mean your battery will die if it is ever fully discharged; it means it is best to avoid fully discharging when possible.) Try to recharge Li-ion batteries when they are at 15-25%. Similarly, avoid heat as much as possible and when (if) storing Li-ion batteries, store them not at full charge.
Update: The only time you should ever intentionally fully discharge a Li-ion battery is if your phone is not properly reading the battery. In other words, if you go from 100% -> 90% in ten minutes but go from 90% -> 80% in one hour with the same amount of usage, that means your phone is not reading the battery output evenly. If this is the case, then fully discharging your battery once and then recharging it can fix the issue of your phone not reading the battery properly. Take note, however, this full discharge/recharge won't increase your battery life -- it will only ensure your phone reads the battery properly.
People often confuse Li-ion and NiCad batteries and try to condition Li-ion batteries by charging/discharging them 4-6 times. Trying to condition a Li-ion battery like it is a NiCad battery (i.e. charging/discharging the Li-ion battery 4-6 times) hurts the Li-ion battery more than helps it. So, be sure to condition your new cell phone's battery, but be sure to condition it properly. Otherwise, you may be doing more harm than good. If you are not sure what type of battery you have, read the labels on the battery - they will always say whether the battery is Lithium-ion or Nickel-cadmium. Good luck and may we all have long lasting batteries".
