I was lucky enough to be a part of the early years of the electric car revolution. This means I have thought about batteries, charging, and battery lifespan much more than the average person. And so, the answer to the question "Is It Bad to Have Your iPhone Always Charging?” is, as usual, it depends. In this post, I'll dive into what some folks have written about, look at the data, share some tips and share my final thoughts.
Is It Bad to Always Charge? Yes and No
It doesn’t really matter if your phone is always charging (say, on a charger on your bedside, then in a car, then at your desk at work), it’s more about whether you are charging your phone to 100% of it’s capacity every possible second or not.
Last year John Gruber at Daring Fireball wrote an article titled “Juli Clover Limited Her iPhone 15 Pro Max to the 80 Percent Charging Limit for an Entire Year” in which he links to and comments on an article that Juli Clover wrote over at MacRumors, where she talks about using the iPhones Charge Limit setting to limit her phone to just 80% (which is what I do). Gruber’s conclusion was to not waste your time and to just let the phone auto-manage the battery, especially if you turn on the “Optimize Battery Charging” setting.
Personally, I think this advice only makes sense if you keep your phone for 1-2 years. However, if you are like me and you keep your phone for more than 2 years (I’m a 4-5 years person), limiting your phone to 80% is probably the way to go. So why is that?
Rough Math
In the Gruber article and thus also Juli’s, they reference some numbers we can look at and extrapolate. I have placed them here in this chart, including doing a straight line degradation analysis (which is not perfect and the degradation would probably speed up over time, but for simplicity sake…).
| Person | Battery % Remaining |
Battery % Loss |
Cycles | % Loss per-Cycle |
Rate Limit 80% |
Year1= 300 cycles |
Year2= 600 cycles |
Year3= 900 cycles |
Year4= 1200 cycles |
| Juli | 94% | -6% | 299 | -0.020% | YES | 94% | 88% | 82% | 76% |
| MacRumors1 | 87% | -13% | 329 | -0.040% | NO | 88% | 76% | 64% | 53% |
| MacRumors2 | 90% | -10% | 271 | -0.037% | NO | 89% | 78% | 67% | 56% |
| Gruber | 89% | -11% | 344 | -0.032% | NO | 90% | 81% | 71% | 62% |
| JOhn (me) | 100% | 0% | 54 | 0.000% | YES | N/A | N/A | N/A | N/A |
As you can see from the numbers above, it is VERY clear that the % Loss per-Cycle is nearly 100% higher if you let your phone charge to 100%, vs. if you limit it to topping out at 80%. Gruber’s personal numbers were the lowest of the group and still clocked in at OVER 50% higher degradation than if he had limited his battery to 80%. And that is just looking at the 1-ish year numbers (my phone is obviously too new to glean anything from).
If we look at the extrapolations, after 3 years of use someone who limited their battery to an 80% charging limit would still have a battery capacity of over 80%, while those who let their phones constantly charge fully would have a battery capacity in the mid-60% range. Personally, I think that sucks. And, the funny part is that if you didn’t self-limit your device to 80% you would be forced to be at that level anyway after just shy of 2 year of use because they would have burned their battery out to that level by that time.
Understanding iPhone Batteries
Your iPhone uses a lithium-ion battery, which have an approximate limited lifespan of about 500 full charge cycles before they hit a max-capacity of 80% (which is generally considered “worn out”). Over time, the battery’s capacity will decrease even more. A batteries health is also affected, negatively, by temperature extremes. The more extreme hot and cold cycles the battery goes through the more quickly it is going to wear out.
How to Check Your Battery Health
You can check your battery health at any time. Go to Settings > Battery > Battery Health. There you can see your phones "Maximum Capacity" % (how much of the battery is still usable), and you can also see the Cycle Count (the number of times your phone has fully charged).
Best Practices for iPhone Battery Health
So, what are some best practices you can do to promote battery health and longevity. Here are a handful to give you some ideas:
-
Either Choose Optimized Battery Charging OR Set your Charge Limit to 80% - This feature learns your charging routine and slows charging when the battery reaches 80%. It charges to 100% right before you typically unplug it. To activate:
- Those Who Want to Charge to 100% - (Settings > Battery > Charging > Optimize Battery Charging) This is the best of the best of Apple automating battery health (and it turns off if you change the charge limit)
- Those Who Want to Limit Battery to 80% - (Settings > Battery > Charging > Charge Limit [move slider to 80%]) - Although you don’t have to move the slider to the full 80% you likely will not get the full benefit unless you do.
- Avoid Extreme Temperatures - Keep your iPhone in environments between 32°F (0°C) and 95°F (35°C). Excess heat, especially during charging, can accelerate battery wear.
- Don’t Let Your Battery Drop to 0% Often - Avoid draining your battery to 0%. It’s best to charge when it hits around 20% to 30%, as staying in the 20-80% range is ideal for lithium-ion batteries health.
- Use Quality Chargers - Stick to quality cables and chargers. Ones that are low-quality or sketchy in any way can have inconsistent energy flow and potentially hurt the battery.
- Keep Software Updated - On occasion, iOS updates can improve battery performance, often through making the system more efficient overall. Always make sure your device is running the latest software.
Conclusion
In short, it’s not bad to keep your iPhone plugged in all the time, but how much you might want to limit the charging depends on how often you replace your phone. If you get a new phone every year, who cares. However, if you keep your phone for more than 2 years, then you might want to take more serious action on how your phone charges. With a few simple practices, you can extend your iPhone’s battery life and ensure its longevity. If you stay smart about your charging, your battery and your wallet may thank you.