1. Do not overcharge. (How long should it be charged?)
Lithium batteries are activated at the factory, so the outdated claim of "activation" by some vendors is misleading. In fact, once the battery is fully charged, the overcharge protection circuit activates, cutting off the charging power, and the battery begins to discharge. After a period of discharge, it starts charging again, alternating between charging and discharging (see the overcharge protection circuit principle above). This back-and-forth charging and discharging actually shortens the battery's charging cycle (discussed later). Generally, lithium batteries are fully charged in 2-3 hours. After 90%, it's basically a slow charging process, requiring only an extra 1-2 hours at most. That is, charge for 4-5 hours, and do not exceed 6 hours.
The idea that new batteries should be fully charged for 12 hours continuously for the first three times is outdated knowledge from the nickel-metal hydride battery era. It's not that you can't charge them this way, and you probably won't have any problems. Lithium batteries have protection circuits, and they won't be damaged, but when the protection circuits activate, the battery enters a "discharge-charge-discharge" cycle, unnecessarily using unnecessary charging cycles and indirectly reducing its lifespan. Furthermore, it's possible that some low-quality lithium batteries might develop problems after prolonged charging.
2. Avoid over-discharging. (When should the battery be charged?)
Many people mistakenly believe that lithium batteries have a limit to the number of charges (actually, it's not the number of charges, but the charging cycle – more on that later), so they try to fully deplete the battery each time, not charging it until it automatically shuts off. This is actually bad practice. It easily leads to over-discharge. Over-discharge directly impacts battery life; one or two complete discharges might render the battery unusable. Therefore, batteries should ideally be charged when they reach 10%, and never less than 3%.
Over-discharge most commonly occurs when using a mobile phone outdoors, letting the battery drain to the point of automatic shutdown or even inability to turn it on, without a charger. This results in the battery being unable to recharge for a considerable period, leading to over-discharge due to self-discharge – this is the most likely scenario. Another possibility is that the battery is left unused for a long time, but before storage, it had very little charge, causing it to become "slow-discharged."
Currently, some devices will remind you when the battery level is between 5-10%, and then automatically shut down upon the second reminder. It's estimated that the second reminder will leave only 2-3% battery remaining, so the remaining power is already very low. Therefore, it is strongly recommended that you do not attempt to turn the device on after it automatically shuts down; charging it as soon as possible is the most important thing. Ideally, you should proactively charge it before the first reminder.
III. What is a charge cycle (or charge-discharge cycle)?
Many people mistakenly believe that the lifespan of a lithium battery is determined by the number of charges, which is incorrect. Strictly speaking, it should be called a charging cycle. A complete charging cycle involves charging to 100% and then discharging to 100%. The lifespan of a lithium battery is approximately 300-500 complete charging cycles. The correct statement regarding lithium battery lifespan should be 300-500 complete charge-discharge cycles.
In other words, assuming a battery is fully charged to 100%, then used 50% and charged 30%, this is not a complete cycle. A complete cycle consists of two 100% charge-discharge cycles, which is actually a 40% cycle. Then you use 60% and charge again...
At 40%, that makes 90% of the cycle. And so on...
Lithium batteries do not have a memory effect, so I agree with Apple's claim that lithium batteries should be used in moderation—charged only when needed, not charged for too long, and not completely depleted.
IV. Environment for Lithium Battery Use
Using lithium batteries in excessively hot or cold environments can affect their lifespan. Therefore, on hot days, avoid leaving your phone in a car or exposing it to direct sunlight. In winter, if the outside temperature is below -20 degrees Celsius, do not leave your phone outside (exposed for extended periods). Instead, keep it in a warm pocket and use headphones (avoid Bluetooth headphones, as they also contain lithium batteries).
Quote:
Polymer lithium-ion batteries: charging temperature range is 0 to +45℃; discharging temperature range is -20 to +60℃; long-term storage environment for batteries is -20 to +35℃.
V. What to do when lithium batteries are not in use?
Lithium polymer batteries have a relatively high self-discharge rate. To be on the safe side, if you're not going to use them, it's best to fully charge them first and then seal them in a plastic bag before storing. Take them out and use them once every 1-2 months (charge and discharge once) to maintain the activity of the lithium ions. Do not store them for more than 3 months; you must take them out and charge and discharge them at least once every 3 months. Storing them unused for too long will reduce the activity of the lithium ions and affect the battery's lifespan.
6. Should USB charging be enabled?
More and more devices now support USB charging, and personally, I think it's optional whether to turn it on or off, for the reasons mentioned above. However, I've seen posts from friends saying that USB charging doesn't fully charge due to insufficient voltage (I haven't encountered this with PDAs, they all charge fully, I don't know why the 580 doesn't), and I've encountered the same situation. Personally, I don't want to have to charge for a short time every time I plug in USB; it's mainly a matter of habit, so I keep USB charging off. If I don't have a power source with me, I can turn it on again to charge, it's convenient anyway. Also, I'm unsure if charging a phone with a non-standard voltage will affect the phone and battery; without knowing the specifics, I personally prefer to keep USB charging off as much as possible.
7. What's the best way to charge it?
One last piece of advice: it's best not to use generic chargers to charge original lithium batteries. Use the original charger along with the charger itself, or buy an original desktop charger. Generic chargers often use incorrect voltage and current, which can damage the original battery. Especially avoid older chargers with discharge functions; they can easily over-discharge the battery and ruin it.
Additionally, some friends have asked about the use of generic lithium batteries, so I'd like to share my personal opinion here—both counterfeit original batteries and genuine generic batteries mostly use lithium-ion batteries (because their cost is relatively low, while lithium polymer batteries have a higher production cost). Firstly, their capacity is definitely not as high as that of lithium polymer batteries (lithium polymer batteries have a higher density). Moreover, lithium-ion batteries are not as safe as lithium polymer batteries. The numerous battery explosions and spontaneous combustion incidents in laptops (less common in mobile phones, but they do occur) stem from the instability of lithium-ion batteries after prolonged use.
Therefore, generic batteries should be especially avoided from overcharging. Don't expect longer charging times to improve performance just because the battery life is short; that's impossible. Also, replace generic batteries as soon as possible after prolonged use; don't be reluctant, safety first. As for charging, you can use any charger—generic ones are fine, even mobile phone chargers—it shouldn't have any impact on the phone (this is just speculation, I haven't researched it).
