No. Next question?
If you insist, here’s a little more information to back that up. Modern batteries simply cannot be overcharged, because they have built-in protection – a cut-off circuit – that prevents that from happening.
Will it harm your battery if you leave your phone charging overnight? Absolutely not. Your phone will detect that your battery is charged and cut off the juice; instead, it will power your device via the mains charger.
Should I wait for the battery to run low before charging?
A more relevant question is whether you’re better off leaving your phone to drain to around 10%, say, before recharging it – a logical conclusion, given that batteries are only rated to be recharged by a certain number of cycles. For example, an iPhone’s battery is rated for 500 recharge cycles before it drops to 80% of its original capacity.
The key thing to know, though, is that charging a phone from 50% to 100% only uses up half a cycle. In fact, it’s better to avoid letting a battery run too long, as a study by Battery University found this wasn’t an effective way to work.
Instead, you’re better off charging when your phone gets to around 50%.
But there’s no need to get obsessive about it. Use your phone to suit your lifestyle, and recharge when it’s convenient for you.
Whatever you do, the battery in your phone will degrade. This doesn’t necessarily sound the death knell for your phone, though, as the excellent iFixit site has guides on how to replace batteries in even sealed devices such as the iPhone 5.