cellphone battery and the lifespan of one

Is there an efficient way to use a cellphone battery (the lithium ion variety) in order to give it the most amount of life? I have read different ways to do this but they disagree.

Whether it be the 80% to 40% rule where you keep your phone charged between these numbers. OR not letting your phone go below 90% and when you can, put your battery in a cool place, like in a refrigerator when not in use. As annoying as this is to do.

Does it matter and should I even try these methods? Thank you

No, it’s a fool’s game. Just let the internal charger do it’s thing, without micro-managing it.

Storing a phone (or any electronics) in a fridge is a bad idea. When you take it out, moisture will condense on it, and potentially cause short circuits. The risk is very small but not negligible. (Taking it out of the fridge in summer is worse than bringing it in from outdoors in winter, because indoor humidity is pretty low in winter.)

I really wouldn’t try to outsmart the phone’s built-in charging circuit. But I would avoid charging it in a place where the phone can overheat (e.g. stuck under a pillow). And I would not intentionally run down the battery. If you’re in a place where you can keep the phone connected to a charger, it wouldn’t hurt to do so, and may save the phone from an additional charge/discharge cycle.

Sitting at maximum voltage increases the rate of break down for lithium ion batteries.
Discharging all the way down to minimum voltage is also damaging.

The engineers who designed your phone also know these two realities. Your battery meter may not really be full when it’s full. Your phone might already shut down before draining the last bit of power. It’s hard to tell if they are already taking the reasonable efforts to extend battery life in that way.

Heat, especially at full charge, can contribute to break down. The fridge has the issues mentioned above for something that is seen as a daily use device. Use patterns can affect heat though. If you are playing that really cool game and the phone is getting warm…maybe take a break. If there’s a choice between the sunny spot you stash it in the car while driving and a shaded nook, pick the shady/cooler spot.

Keeping an eye on what you install and what is constantly running is another way that might help. That can both be a mild heat issue and an issue with requiring more cycles from the battery. I keep GPS and wifi off and don’t install social media apps that are constantly checking for updates. You can look at things like shutting the phone off while you sleep if you are just going to turn the ringer off or not answer it anyway.

Think about it this way: You can do all the right things and maybe extend battery longevity by 15%-20%, best case scenario, which is maybe another 2-5 months out of a battery’s probable 2 year lifespan. In that time you’ll likely have either switched to a new phone, or the battery would be performing so poorly you’re thinking about replacing it anyway and are just trying to drag it out as long as possible.

If I were you: Don’t worry about it. At ALL. Pay $80-$100 every 2 years for a professional shop to just replace your battery for you. Live your life and find something bigger to worry about.

It’s more of what not to do. Don’t keep your phone fully charged, don’t let you phone ‘sit’ at lower than 20% — all time both above and below 40% is damaging and will shorten the life, 0% being highly so, while 100% being moderately so - this gives rise to your 80-40 rule or, as I know it, 80-20 and yes that can prolong the life, also shorten the time and add to the efficiency of recharge. Don’t expose your battery to excessive heat or moisture (including condensation).

Cycle life is basically meaningless with Li-ion, is it a hold over from NiCd and Nimh where it meant something and became an industry standard which is still with us today. But in recharging heating may be a issue, including rapid discharge.


Leaving a lithium ion battery at 100% causes continuous loss of capacity. Discharging below about 40% also causes loss of capacity. Cycling it (using it at all instead of just keeping it between 40-80%) causes loss of capacity.

So yeah, basically, if you use your phone, you’re damaging the battery. Letting is discharge all the way to 20% or less is damaging it more. Letting it fully charge and then stay charged is damaging it a lot - but so is stopping charging at 80%.

You can’t win. As the other posters in this thread suggest : look, you can get replacement batteries for $30-$50 (VERY IMPORTANT : buy GENUINE replacement batteries!!! Do NOT buy cheap knockoffs, get NAME BRAND batteries from a reputable store, NOT ebay!). Even paying a pro to change it doesn’t cost more than $100.

Or you can go on iFixit, and most any phone you might have, they will have the step by step instructions to change the battery. Sometimes it is quite hard, but the instructions are there.

This just isn’t true. Lithium ion batteries have limited useful lives, as other posters have discussed. Even if you did everything right, charging and discharging under optimal, temperature-controlled laboratory conditions, they will still lose useful capacity over time. Even if you did absolutely nothing to it, they will still chemically degrade over a few years.

Here’s Battery U’s writeup about it:

So they WILL degrade, mostly through use but also through age, and will suffer somewhat from abuse, but modern electronics understand user behavior and try not to let you damage it (under/overcharge) too much. But they will still die gradually and need replacement in 2-3 years of a typical cell phone or laptop’s use.