Preventing Battery Swelling

Hi

To help avoid damaging your iPhone and shortening the battery life, be sure to follow Apple's guidelines.

These include the Important handling information in the iPhone User Guide, which includes information about keeping your iPhone within certain temperature ranges and not subjecting it to dramatic changes in temperature or humidity.

Apple advises that you should only use genuine Apple Lightning to USB cables or Apple-certified / MFi cables - and also recommends using genuine Apple USB Power Adapters.

More information:

https://www.apple.com/batteries/maximizing-performance/

Keeping iPhone, iPad, and iPod touch within acceptable operating temperatures - Apple Support

http://help.apple.com/iphone/9/#/iphbbe12ba1

Usage habits are the most common reason. These batteries have a finite number of times that they can be charged (usually several hundred) before they will begin to swell/fail. Once you exceed that number you will notice swelling.

Not using an approved charger would be another. I have had many customers tell me that their aftermarket chargers no longer work on their devices. That, actually, is a good thing. Apple goes to great lengths to make sure that we have a quality product to enjoy, so it is always a good idea to use the recommended products and kudos to Apple for ensuring that only approved chargers works.

Overcharging is a third cause. There are a number of "smart chargers" out there, and I believe that the OEM Apple Charger is one of those, that will actually stop sending a charge when it detects that the battery is full. If yours does not, charging overnight is a bad idea. Most devices dont actually take more than 6 hours to charge and you would be amazed at what the extra time on the charger can do if it continuously feeds juice into the phone/tablet. Though not generally an issue with Apple products, overheating can do it too.

Zvonimir Blazevic wrote:

Overcharging is a third cause. There are a number of "smart chargers" out there, and I believe that the OEM Apple Charger is one of those, that will actually stop sending a charge when it detects that the battery is full. If yours does not, charging overnight is a bad idea. Most devices dont actually take more than 6 hours to charge and you would be amazed at what the extra time on the charger can do if it continuously feeds juice into the phone/tablet. Though not generally an issue with Apple products, overheating can do it too.

The charging circuitry is built into the phone. iPhones, like most modern phones, have smart charging circuitry. So, yes, it's safe to leave them on charge overnight. The part that plugs into the wall is nothing more than an adapter.