No, this 90 % overcharging thing is not an urban myth.
Nintendo has added an interesting new feature for the Switch 2.
As reported by Nintendo Life, there is a new setting you can toggle to “Stop Charging Around 90 %.” When you turn this setting on, charging starts slowing down when the Switch 2’s battery gets close to 90 %.
While some consumers have heard of some variation of the 30-90 rule or 20-80 rule when it comes to charging phones, there’s some widespread skepticism around it. There’s this reddit where some users share their belief that the 30-90 rule is mostly an urban myth.
Now, to nip this in the bud, here’s a link to the scientific study on discharge of lithium-ion batteries. If you aren’t interested in reading though a 420+ page thesis, you can read a briefer explanation here.
But to share an even simpler explanation, this 30-90 rule specifically applies to devices that run on lithium-ion batteries. Scientific studies found that these batteries will last longer if you don’t let them charge beyond 90 percent, and you don’t let their battery go below the range of 30 percent.
These findings are based on an understanding of how the chemicals in these batteries work, and subsequently how to make them work as batteries for much longer. If you don’t ‘follow’ these rules strictly, it doesn’t mean that your phones or devices will be destroyed sooner. But you really can extend the lifespan of your devices beyond what you usually expect to get out of them. We do assume most consumers will want to make their devices last as long as possible.
It’s also worth noting that there are other factors as well. So it’s also imperative that you make sure your devices don’t overheat too much. And the lithium-ion battery in your phone, tablet, electric vehicle, etc., can overheat for many reasons, not just from overcharging.
There are also many ways to mitigate this situation. For example, if you use a gallium nitride/GaN charger, the charger will recognize when a connected device is fully charged and will stop overcharging. Another way of dealing with this is if the device has an internal setting to stop charging so that it doesn’t go beyond 100 %.
If you were still skeptical about this practice, you should know that both Samsung and Apple offer similar 90 % stop charging features for their phones and tablets. So Nintendo is simply adopting a best practice that emerged after they first released the Switch, and should probably be the default for lithium-ion devices moving forward.
