Optimal charging rate for battery longevity?

Aaralli · December 11, 2020

I just bought myself a OnePlus 8. I want to keep the battery as healthy as possible for hopefully the next three or so years. However, I like charging overnight. So far, I usually get my device down to 45% on weekdays and 20% most weekends. Would it help my battery to use a 5V 1A slow charger overnight so I don't have to worry about keeping it at 100% for a long period of time while I sleep?

Bombastinator · December 11, 2020

25 minutes ago, Aaralli said:

I just bought myself a OnePlus 8. I want to keep the battery as healthy as possible for hopefully the next three or so years. However, I like charging overnight. So far, I usually get my device down to 45% on weekdays and 20% most weekends. Would it help my battery to use a 5V 1A slow charger overnight so I don't have to worry about keeping it at 100% for a long period of time while I sleep?

My understanding is that holding a battery a a given charge does not wear it. It’s charging to that level in the first place. As to whether slow or fast charging will produce more wear I don’t know. One would think slow charging would cause less wear but I don’t know.

porina · December 11, 2020

The battery management in smarter devices like phones will take care of it better than people think. It doesn't matter that you have a power source connected, it will only charge when it is needed. As the battery level increases, the charge rate will lower naturally anyway due to battery chemistry. At or near 100% the controller will only occasionally top up.

Darkseth · December 12, 2020

Tbh, i wouldn't bother with 5w Chargers. Takes way too long.

Use the charger, that's included, because Oneplus uses a proprietary tech, where they moved the charging circuitry into the Charger itself, which reduces Heat in the Phone itself - which is better for the Battery.

However, i keep an Eye on Charge%, and unplug it at 90-92%~. I would do 80-85%, but Android's On-Screen-Time only resets after you charged it over 90%, which sucks.

Without that, i would start charging at 20-30%, and unplug at 80-85%, which was always plenty to get through a Day.

And because Oneplus' Charger is fast enough, i never charge over the Night, unless i fall asleep.I charge at anytime, it falls below 30% for a short while, and that's it.

Charging 2 times from 30% to 80% (50% each, 100% in total) is MUCH better for the battery, than charging it once from 0% to 100%.

What's most stressfull for the battery are the last xx% up to 100%. Like, charging from 90% to 100% is much worse for the battery, than charging from 50% to 60% for example, that's why you want to stop at 80-90% max.

You can download the App "AccuBattery", it takes this Approach, calculates your remaining Capacity, and also shows how much "cycles are used", when you charge up to xx%.

xyro27 · December 12, 2020

The best thing you can do is to use that 5W, 1A charger. It should have no problem filling the device up overnight (depending on how long you sleep ) and will mean the battery spends the least time possible at 100%. Many OEMs state that batteries should not be stored at full charge (which in reality is not full charge, lots of companies have BMS tweaks that under/overreport 100 and 0 respectively), but for overnighting it, I wouldn't worry, even if it's cumulative.

There are more and more companies these days rolling out charging settings (usually called adaptive charging or something like that) that charge the phone slowly overnight, reaching 100% just before their morning alarm is scheduled to go off. I believe Samsung and Google do this and check out this article re: OnePlus (sorry, the Verge is the only site I could find) https://www.theverge.com/2020/1/7/21054830/oneplus-optimized-charging-battery-overnight-overcharging-percentage

The main killer of batteries is heat. Never leave your phone in the sun, hot car, etc. High-intensity apps will also spank a battery with power draw and heat, but remember you gotta do what you gotta do. Don't baby it, just be smart and you'll definitely get three years.

Great site for Li-ion info: https://www.theverge.com/2020/1/7/21054830/oneplus-optimized-charging-battery-overnight-overcharging-percentage

Kc7vwc · December 14, 2020

I think Linus did a video a while back, where the heat & the cycles were there worst part of modern batteries.

For cycles, you want to do a single charge. Going from __% up to however much you consider full, all in one go.

Example: Don't charge it from 25% to 60% and then pull it off the charger, only to put it back on later & finish up to full.

That's two separate cycles of chemical charge/discharge.

Charging docks in cars are the worst for this, as you're probably using the dock multiple times per trip outside the house. House to store = charging. Shopping = discharging. Back in car = charging, on & off for each stop you make.

On top of that, many new devices are being programmed with smart charging, to learn your 'typical' charging habits. If you only charge at night, and wake up at the same time most days, it can learn how to throttle the charge so it peaks just as you wake up.