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The two big issues with batteries are how long a battery lasts, in years, before it needs to be replaced (battery lifespan) and the amount of time a device runs before it needs to be recharged (battery life). This page addresses each.

All Lithium-Ion batteries can only be charged and drained a certain number of times. Each charge limits the maximum power capacity that the battery can store. That is, each charge destroys the battery capacity, just a little bit. Thus, batteries lose storage capacity over time.

Two things that are useful to know about a battery, on an ongoing basis, are the maximum charge capacity and the number of charge cycles it has gone through. Both give you an idea of how old your battery is. Not only in terms of years/months but old in terms of its expected life span.

The maximum charge capacity is a percentage of the original out-of-the-box charge capacity. On a new battery, it should be 100%. Note that this percentage is different from the percentage typically displayed. For example, if the original design capacity was 6,000mAh and the battery now can only store 4,000mAh (perfectly normal wear and tear) it has lost one third of its original capacity. A computing device, however, will report that the battery is 100% charged when its capacity is 4,000mAh. If your device does not last as long on a "full" charge, this is why.

Keeping a Lithium Ion battery fully charged at all times shortens its lifespan. Batteries last the longest (total lifetime in years, not just making it through the current day) when operating between 30 and 80% charged. A laptop that is plugged in all the time, should be set to never charge over 80% (maybe even 70%). Lithium-Ion batteries are under the most strain internally when they are fully charged or completely empty. They are the happiest at 50 percent charge. When storing a device for a long time without using it, do what you can to prevent the battery from fully draining.

Very high temperatures (above 95 degrees F) can permanently degrade battery capacity. If a device gets noticeably hot while charging, unplug it.

Fast charging degrades Lithium-ion batteries more rapidly than the relatively slow 5-watt chargers of old.

A Brand-X charger could damage the battery. Chargers differ in the controls that limit the amount of current delivered and stop a device charging when the battery is full. An off-brand charger might not have such rigorous safety settings. If too much current is delivered to a battery it can leadi to degradation.

FYI: Charging a phone from a laptop computer does not damage the battery. This does a slow charge which, in general, is a good thing. Leo Notenboom has a good introduction to the concepts of Volts and Amps here Why Does My Phone Charge Slowly on Some Chargers? (Nov 15, 2023)

FYI: A smartphone battery typically works at optimal capacity for roughly two to three years.

FYI: Battery Percentage: It is very helpful on a mobile phone to have the current battery percentage always displayed.
 iOS: Settings -> battery -> battery percentage (requires iOS 16.1 or later)
 Android: search Settings for "Battery Percentage" (tested on Android 12,13,14)




iOS, iPhone, iPad





Dim the display and use a dark background
   iOS: Settings -> Display & Brightness -> use the slider bar
   Android 14 Pixel: swipe down twice from the top of the screen, move slider left/right
   Android 14 Pixel: Settings -> Display -> set a Brightness Level and turn off Adaptive brightness

Turn off Wi-Fi and 4G/5G and BlueTooth and turn them on, only when needed. Ditto for Location/GPS.

Put a cellphone in low power mode

  1. iPhone and iPad: Settings -> Battery -> Low Power Mode
    I have read that Low Power Mode will automatically kick in when the battery falls below 20%. Manually turning it on only works if the battery is below 80%, above 80% Apple knows what is best for you and they will ignore your wishes. From Apple: Use Low Power Mode to save battery life on your iPhone or iPad Published September 26, 2023
  2. Android: maybe swipe down from the top and look for Battery Saver
    Maybe Settings -> Battery
    Maybe Settings -> Battery and Device Care -> Battery -> Power Saving mode

Limit the activity that apps can perform when they are running in the background.

  1. iPhone: Settings -> General -> Background App Refresh
    Choose which apps get to refresh periodically on their own and which ones get updates only when you are actively using them.
  2. Samsung Android: Settings -> Battery and Device Care -> Battery -> Background Usage Limits
  3. Pixel Android 14: Turn on the Battery Saver feature. It both sets a dark background and blocks background usage.


  1. Stop Siri from listening for your command: Settings -> Siri & Search -> turn Listen for "Hey Siri" off
  2. Turn off AirDrop: Settings -> General -> AirDrop -> Receiving Off
  3. There are two screen brighness options and they arm wrestle with each other. To insure that you get the brightness you want, turn off the auto-brightness option
    Settings -> Accessibility -> Display & Text Size -> disable Auto-Brightness
  4. The iPhone 14 and 15 have an Always-On display option. Turn that off
    Settings -> Display & Brightness -> disable Always On
  5. Turn off Location: Settings -> Privacy - >Location service
  6. Turn off Find My: Settings -> Your Name -> Find My -> Find My iPhone -> disable it
  7. And FYI: Don't turn off ProMotion to save iPhone 15 Pro battery life by Ben Lovejo for 9to5Mac. November 16, 2023






Lithium-ion batteries swell in size when things have gone very wrong internally. A swollen battery is dangerous. Do not charge a device with a swollen battery. If the device is running, turn it off. The battery must be replaced and carefully recycled. Until you do, keeping it cool lessons the chance of a fire. In case it does catch on fire, keep it on non-flammable material. If you try to remove a swollen battery, do not puncture it. Maybe contact the hardware manufacture for specific instructions, if not removal instructions, then disposal instructions.

Why do batteries swell? Overcharging. Heat (especially over 100 degrees F). Physical damage (you dropped it).



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