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Cell Phone Charging 101

Tech - by Joe Weber - updated on 2/14/2023

Charging a cell phone

New cell phones and smartphones are quickly becoming some of the most expensive devices that we need and use on a daily basis. Knowing how to properly charge your phone is key to ensuring they last a long time to avoid having to spend all that money for a new phone sooner than needed. Keep reading to find out some of the best tips to ensure your phone battery has a long life.

Is It True That You Should Never Charge Your Phone to 100%?

This is something that we all do. We leave our phones on the charger until the battery is charged to 100%. Is doing this actually harming the battery? According to Asidor Buchmann  , CEO and founder of Cadex Electronics and the founder of Battery University, charging your phone to 100% is actually not ideal for the battery. Lithium batteries found in rechargeable phones today do not like to be fully charged, especially when it's exceedingly warm out and the battery can get hot.

What Is The Optimal Charging Percentage?

In an ideal situation, you should never let your phone drop below 20% or charge higher than 80% for optimal battery life. This is not always feasible with smaller batteries like the one in your phone. Larger batteries seen in electric vehicles are designed and built with this in mind and are much easier to stay in that range.

Should I Charge My Phone Overnight?

Another thing that almost all of us do is plug our phone in when we go to bed and unplug it in the morning when we wake up. It will be a surprise to many people that this too can actually be harmful to your phone's battery. As we learned earlier, the sweet spot is between 20-80% so unless you miraculously wake up when the phone hits 80% it's better to charge your phones during the day when you can keep an eye on your charge level as it's charging.

If you do charge your phone overnight, we recommend turning on Optimized Charging if your device has the option. If it doesn't, what happens is the phone reaches 100%, stops charging, then as soon as the device drops to 99% it charges to 100%. This constant charging, not charging cycle can be damaging to your phone.

What Is Optimized Charging?

Apple has developed a tool that is now built into all new iPhones, iPads and even new Macs to aid in extending the life of your battery. This feature is completely automatic and is now enabled by default on new Apple devices.

To turn on or off:

  1. Tap Settings
  2. Tap Battery
  3. Tap Battery Health & Charging
  4. Toggle the switch for Optimized Battery Charging

With Optimized Charging on, your phone will learn your daily charging routine using AI and will delay charging past 80% until shortly before you need to use the battery. This prevents the battery from being at 100% for long periods of time which can be harmful to the battery in the long-run.

Is It Bad to Let My Phone Die?

It's actually a common misconception that you should allow your phone battery to completely die before recharging. Modern lithium batteries that are used in phones today will wear out much faster than they should if you constantly drain the battery to 0%, or let it die, before recharging.

The best thing you can do for your phone is what's called a partial discharge. Don't let your phone die, instead plug into a charger before it displays the prompt to turn on "low power mode", ideally around 30-40%, then unplug at around 90% to increase its lifespan.

Is It Safe to Charge My Phone Multiple Times Throughout the Day?

Yes. Lithium-ion batteries actually like being charged in short spurts. If you work in an office and are up moving to meetings throughout the day, plugging your phone in for 20 minutes here and 10 minutes there may actually be beneficial for the health of your battery.

Now, if you have to charge your phone multiple times a day to get through the day, then it may be time to stop into Batteries Plus for a quick and inexpensive battery replacement.

Do "Fast Chargers" Damage Batteries?

Chances are you've seen the words "fast charge capable" if you've purchased a new smartphone in recent years. What this means is that the phone is safely able to use a compatible high-capacity wall or car adapter to reach higher charge levels faster than a traditional charger. You might think that pumping higher amounts of energy into the battery will damage it but, no, using fast chargers on phones that are built to support them is perfectly safe and will not harm your phone's battery.

What About Wireless Chargers?

Wireless chargers are all the rage these days. Most phones are coming with wireless charging capabilities and they are so easy to use! No fumbling with cords or having to plug anything in. Wireless charging doesn't inherently harm your battery but wireless chargers do generate more heat than a traditional charger, which can be detrimental in the long run. It is normal for your phone to get warm when using a wireless charger but it should never be hot to the touch. If your phone is hot, this could simply be that the phone is not placed on the charger correctly, or worse, a problem with the battery itself.

How Do I Check the Health of My Battery?

Most phone brands have built in battery health monitors in their phones software. Here are the steps to check your phone battery's health on the two major brands out there.


  1. Tap Settings
  2. Scroll down and tap Battery

This screen will show you the charge pattern, battery level history and the activity on the phone that drains the battery.

  1. Tap Battery Charging & Health

This screen will show you the maximum capacity your battery currently has which will lower as your battery ages. If your battery is displaying a warning and your maximum capacity is lower than 80%, it may be wise to reach out to the experts at Batteries Plus for a replacement battery. This screen also provides the toggles to turn on and off Optimized Battery Charging if you tend to charge your phone overnight.


  1. Go to Settings
  2. Tap Battery and Device Care
  3. Tap Diagnostics
  4. Then Battery Status

This screen will provide details on the life of the battery (ie. Good), the capacity of the battery and whether or not the battery may need to be replaced.

Other Android Phones

You can download third party apps through the Google Play Store that can provide details of the battery health or on many Android phones you can dial *#*#4636#*#* from the phone screen to see detailed information about your battery.

What Are Some Charging Accessories I Should Have?

Having some helpful charging accessories on hand will make charging your phones and tablets easier.

  • Extra Chargers - Especially helpful if you work from home and would like to charge your phone in your office without having to move your charger around.
  • Wireless Chargers - Convenient and easy to use, these are great for those looking for an easy, place your phone and go charging solution.
  • Power Banks - Always a great option if you're out and about and need a quick boost. Just plug in your phone and keep going. The Goal Zero 22050 Sherpa is the ultimate travel companion with multiple USB ports, wireless charging and even a standard outlet for your laptop.
  • Goal Zero Power Stations - For the person that wants to be prepared for anything, the Goal Zero power stations provide plenty of power to charge up your devices when the power goes out.
  • MagSafe (Apple) - If you own a new iPhone that features MagSafe (iPhone 12 and newer) then there is nothing better than snapping the charger onto your phone and never worrying if it's placed right. Just set your phone and it uses magnets to keep the phone on the charger until you take it off.

Tips to Extend Battery Life

  • Avoid "Parasite Loads"
    Try not to use your phone while it is charging. Doing so can confuse the battery by creating "mini-cycles" which will speed up the aging process of the battery.
  • Close Unused Apps
    Closing out of apps that you are not using will help reduce the amount of battery that your phone consumes during the day by reducing the resources required to keep all of those apps open in the background.
  • Limit the Amount of Time Plugged in at 100%
    If you have the option, use Optimized Battery Charging to avoid continuous charging after the phone reaches a full charge. If you don't have that option, consider charging the phone during the day when you can monitor the charging.
  • Stay in the 20-80% Charge Range
    For the long term health of the battery try to keep the phone in the sweet-spot range of 20-80%.
  • Keep the Phone Cool
    Excessive heat damages batteries. Remove the case from your phone when you plug it into a charger and try to avoid using the phone in extreme heat. The optimal ambient temperature range for batteries is between 32℉ and 95℉.
  • Use Battery Saving Features
    When you get that pop-up to turn on low power mode, power saving mode or whatever it is called on your phone, use it! This will turn off unnecessary software to save energy and squeeze out more time. Don't be afraid to use this before your phone gets down to 20%.

Should I Replace My Battery or Buy a New Phone?

While it may sound tempting to just do it yourself, there are a lot of tiny screws, easily breakable components and it requires strict attention to detail, this repair should be left to the experts. Having your battery replaced by the certified technicians at Batteries Plus is quick, most battery replacements take less than an hour, are inexpensive, convenient, and all of our repairs come with a nationwide 6-month warranty in the unlikely event that something happens after your repair. Walk out the door with your phone working like new and saving hundreds or even thousands versus buying a new phone. Visit us online to schedule your repair or stop into one of our local Batteries Plus stores to see how we can help you.

Learn why having your repair done at Batteries Plus is a smart choice in "Why You Should Have Your Phone Repaired at Batteries Plus" and why our repair technicians are some of the best in the industry by reading "What is WISE Certification and What Does It Mean for Cell Phone Repair?".

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