Your phone's battery lifespan vs the norm
Does your phone’s battery last as long as it should?
But does yours seem to get shorter way earlier? If yes, then perhaps your charging habit all through the years has been silently wrecking your phone’s battery health
How often you charge will affect the battery life, for better or worse. In short, the more often you top up your battery, the better. To REALLY minimize battery degradation, top up for every 10% drop in battery level. And keep your battery level as close to the middle (50%) as possible. Impractical and unrealistic, yes they are. But these are only for maximizing battery health. There are much room for tweaking to add more convenience into the mix.
Why are these recommended? Because unlike the old Nickel, lithium-ion batteries get stressed by:
- Depth of discharge a.k.a how much battery is used before recharging.
- Extreme battery levels, both low and high.
The widespread, outdated beliefs about battery
Surely, you must had also heard the opposite, which are:
- Batteries need to be drained completely and recharged to 100%
- Batteries lose capacity if they are repeatedly recharged after only being partially drained.
And these two suggest that frequent charging will degrade battery capacity instead, which WAS true—for the Nickel-based batteries; for they are cursed with memory effect. Simply put, they will “forget” their full capacity if they aren’t discharged and charged from 1% to 100%.
Now, cycling your lithium-ion battery from 1% to 100% habitually will take a chunk of its battery life away.
How deeper discharge & low battery level degrade battery capacity
To clarify, battery by itself, regardless of your habit, will deteriorate. Even when just sitting on a shelf. As you cycle the battery, irreversible internal structure changes happen. The lithium count gradually drops as more and more get lodged onto the anode during normal usage; they form a restrictive layer (named solid electrolyte interface) that grows and increases battery’s internal resistance, which ultimately lowers the battery capacity.
Tying this to your charging habit, the restrictive layer grows faster with the following factors:
- High discharge rate (how fast the battery is consumed)
- Deeper discharge
- Low battery level (as is high battery level, but with different structural change)
Worse is, the degradation of deep discharge escalates the further the battery is in its life cycle. The older your phone is, the more your unhealthy charging habit damages your battery.
How much discharge is considered deep?
There is no boundary: the deeper you discharge it, the more stress it inflicts on the battery. Meaning that topping up frequently extends battery life for lithium batteries. In this regard, doing a full discharge, which is to run your battery down to 0%, is the most stressful. The table below detailed the number of usable cycle depending on the habitual depth of discharge.
(Source: Battery University – How to Prolong Lithium-based Batteries)
What battery level is considered low?
Again, the same concept applies: the closer it is to 0%, the more harmful it is to the battery. (And same goes to battery levels closer to 100%.) The least stressful battery level is around the middle (50%). Also a reason why Apple suggests storing batteries at half-charged.
Except this time, there is a boundary set by phone manufacturers.
Something we’re all too familiar with …
Definitely a standard you can fall back on. Plus it’s convenient: your phone will never fail to remind you when it gets this low. Though if you’re feeling particularly protective of your battery, you can recharge before it gets to 20% battery.
The exception to the rule
That you should, on certain occasion, run your battery down to 0% (full discharge).
- Your battery percentage drops suddenly, say, it stays unusually long at 50% then jumps to 35% in the blink of an eye.
- Your battery shuts down when there’s battery left.
If these happen, do a full discharge followed by a full charge for recalibration.
To calibrate your phone’s battery:
- Run your battery down until the phone turns itself off (without charging in between)
- Charge your phone to 100% while the phone is off
- At 100%, unplug from charger and power on your phone
- If after powering on the battery isn’t 100%, charge it to 100% and unplug
- Done! The full discharge and recharge cycle has recalibrated the battery’s reading
Note: this does nothing to save battery life; in fact, it achieves the opposite …
Why does this happen?
Battery readings are thrown off because unlike the actual electrochemical battery, the digital battery (the smart chip on the battery) that shows us the reading doesn’t age. The graph below visualizes the inconsistency between the two created over time.
(Source: Battery University – How to Calibrate a “Smart” Battery)
Note: the values are for demonstration only.
How often should you calibrate your battery?
- Whenever your battery starts showing inaccurate reading; otherwise, refrain from full discharge as it degrades battery capacity.
- When the phone isn’t used for a long time.
Now, putting everything together.
How often should I charge to prolong battery life?
It’s a matter of balancing convenience with battery longevity. To recap …
The best but unrealistic way:
- Recharge once the battery drops 10%; deeper discharge degrades battery more.
- Keep the battery as close to the middle range as possible. Extreme battery levels, which are levels closer to 0% and 100%, reduce battery capacity.
But that defeats the purpose of using a smartphone, which is CONVENIENCE. That said, what you can do instead are:
- Recharge whenever convenient. Don’t let it fall below 20% (or higher) and avoid fully discharging the battery unless calibration is needed.
- Unplug at battery level between 80% (or lower) and 100%. Don’t let your phone stay at 100% level for too long, i.e., plugging to charger after fully charged.
There’s no absolute rules to follow. Most suggest the 20 – 80 rule, which you can definitely follow. You can even do 45 – 75 or others.
As long as you understand what’s harmful to your battery, you can tailor your charging habit according to your needs and daily routine. Because while you can definitely improve battery life significantly, it’s pointless if it demands sacrificing your enjoyment and convenience, which is what your smartphone is supposed to bring you.
P.S. If you prefer charging to 100% for maximum runtime, check out the cable that auto disconnects the battery at full charge for you.
Editor’s note: This post has been completely revamped and updated to improve comprehensiveness and accuracy.