Will charging a cellphone too long hurt the battery?
Question:
My question is regarding cell phones and their associated chargers.
Just for the sake of argument, let’s assume I leave my cell phone on the charger for 12 hours every day. And every day it only takes 3 hours to charge the battery in the cell phone. Am I doing anything long term that will shorten the life of the cell phone battery or the cell phone itself?
So this question has nothing to do with perceived energy savings, I just want to treat my phone in the best way possible.
Inquiring minds want to know!
Answer:
At the time of this writing, lithium batteries (probably what’s in your cellphone) have a lifespan defined by recharge cycles. So if you charge up to 100%, then drain the battery, then do that process 300 to 500 more times, you’ll probably kill the battery: Lithium batteries can re drained and recharged 300 to 500 times before they’re useless.
I start with that, so you know the limiting factors here – that’s how to kill a lithium battery. It doesn’t have as much to do with charging methods.
Now, if you charge a lithium battery too long, or drain it too far, you can indeed damage the battery. But there should be safeties on the equipment you use: your phone should stop working long before the battery is completely drained. And as for overcharging, there should be an intelligent circuit somewhere in the phone or charger so that, when the phone is charged up, the charge process stops.
What often happens at that point is that the charger may appear to keep charging (you may notice a “charging” indicator), but in reality there is zero charge going to the battery. The charger will periodically test the battery, and if the charge falls below a certain threshold, the charger will kick in again and briefly top off the battery.
That’s the way such devices should work, anyway. I can’t promise anything about a specific device without testing it myself. But what I’ve written above is my understanding of how most lithium-battery-using devices work, usually computers, cellphones and other consumer devices.
I write all the above stuff so you can better understand my answer to your specific question: If your cellphone takes 3 hours to charge, and you leave it on the charger 12 hours per day, are you damaging the phone or battery? My answer is “probably not”, since while I can’t promise anything, my understanding is that your cellphone will charge up for three hours, and then the charging process will shut off, with periodic “check up” charges over the rest of the 12 hours.
For all intents and purposes, I’d say to continue charging your cellphone 12 hours if that’s what works for you, like if you plug it in before you go to bed at night. That’s what I do myself. You are probably not damaging the phone.
