This isn’t one of those recipe blogs where you have to scroll for half an hour past an anecdote about the writer’s grandma before you get what you came for. See the title up there? The answer to that question is no. (Also our grandma is fine, thanks for asking.) If that’s all you wanted to know, feel free to go on with your life—we’re pretty proud of our feature on the Apple vs. Samsung war, if you’re looking for reading suggestions. If, however, you’d like to know why it’s actually a very bad idea to discharge your phone completely, and are interested in some simple strategies to extend battery life, stick around!
A Horrible, No-Good, Very Bad Idea
If you squint, and don’t know very much about how batteries work, you can guess how someone might’ve come up with this widely believed “hack” to extend battery life. It makes sense to think that, by waiting until the battery is completely discharged to plug it back in, you reduce the number of charges cycles the battery must undergo. Some also imagine it is less strenuous to charge a completely empty battery, rather than “mixing” old and new charge. (Spoiler: this is not a thing.)
In reality though, the li-ion batteries used by virtually all consumer electronics actually don’t like being fully discharged very much. There’s a lot of action going on within a battery casing as electrons are cycled from the anode to the cathode through a series of electrolyte buffers that regulate flow (and power whatever device the battery is attached to). As long as there is a relatively steady amount of charge within the battery, this cycling causes little wear on the internal architecture of the battery.
By some estimates, frequently fully-discharging can reduce your battery’s capacity by 70% over 300 to 500 charge cycles!
The problems start when a battery is fully-discharged (or, for that matter, kept at 100% charge). Forcing the cathode to charge completely from zero causes degradation of the physical materials, and potentially adverse reactions within the electrolyte solution. Think of your techniques for extending battery life as you would putting oil in a car’s engine—a steady amount keeps everything moving along safely, but letting it dry out completely quickly adds up to serious and costly damage.
Read this instead to extend battery life
The safe operating rage for a li-ion battery is 30%–80%. You can extend your battery life by keeping an eye on your charge level and using high quality charging peripherals. We’ve also prepared a number of useful guides for those with a vested interest in extending battery life:
- Extending Android Battery Life
- Will Portable Chargers Damage Batteries?
- Why Batteries Lose their Charge
In a future post, we’ll be elaborating more on how to keep a new phone battery functioning at a high level.
I have a 4.8 amp battery charger and use it for the ravpower rp-pb13 it seems to charge nice is this a bad idea? Dont want to kill this battery it is the best one i have.
Hi Douglas,
Both the charger and the power bank have limited current circuits, so you don’t need to worry!
Thank you for this and the science behind it. My other half, no matter what the manufacturers say, is adamant that they need to be fully discharged and so having the science behind it (he is an engineer) is brilliant.
Happy to have helped!
He’s likely thinking about older batteries, such as the ones they used in laptops before li-ion took over.
Nimh
My i phone cuts off when battery power indicates at 56%. Is there a battery memory to cause this? If so, is there a way to erase this memory eg. by force discharging? If so, how could you do this on the phone in the cut off mode?
Hi there we suggest contacting Apple to help with your particular problem.
Either your battery doesn’t want to put out the needed current, when it’s half discharged, or there’s a miscalculation of your percentage by your iPhones firmware.
The most likely one is, your battery needs replacing, especially if it’s been through over 1000 charging cycles.
I just replaced the worn out charger that came with my Andriod. The new charger worked fine when the required charge needed 2+ hours. However, the charger appears not to charge while I am using the phone.
Moreover, it seems not to charge when turned off, unless it is discharged a specific amount. Are new chargers designed to minimize use of electricity? Something different is going on! What is it? Or am I simply going CRAZY?
Hi could you please email the problem and include your RAVPower model. Our customer support team will be able to help. Thanks!
I think you might have replaced it with a charger that gives less current when it’s charging.
For example: your charger was 2.5amps, but your replacement one is 0.5amps/500ma
That drawing at the very beginning is hilarious
Haha I agree!!