Electronics

How to extend the life of your lithium-ion batteries

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Lithium-ion batteries degrade over time, which is annoying to you and me, but very handy for smartphone manufacturers, who are all too keen to sell you a new one every two years. There are, however, ways you can look after your batteries to make them last longer, and this advice isn't restricted to just your phone.

A team at the University of Michigan, Ann Arbor, "plowed through scores of academic papers and manufacturers' manuals" to put together a list of best practices to preserve the life of lithium-ion batteries as long as possible. Almost every component of the battery degrades over time, including the anode, cathode, electrolyte, separator and current collectors. In a new study, the team identified several major factors that lead to battery degradation, all of which are avoidable.

Firstly, avoid exposure to high and low temperatures, especially during charging. If your phone is feeling hot on the charger, take it off. Likewise, avoid charging it in very cold conditions. Temperature extremes "can accelerate degradation of almost every battery component." For this reason, some electric car manufacturers recommend leaving the car plugged in on very hot days, so the battery cooling system can run. As a guide, try not to charge if the temperature is outside the range of 50-95° F (10-35° C).

Secondly, batteries hate being too full or too empty. Ideally, you'd never let them charge over 80 percent or discharge to less than 20 percent, because being outside the 80-20 percent range, on either side, stresses and degrades a lithium-ion battery. If you need the endurance of a fully-charged battery, then go ahead and do a full charge – but take the device off the charger straight away once it hits 100 percent. That means charging phones overnight, and leaving seldom-used batteries on the charger, are both bad news, so figure out a charging routine that's both convenient and kind to your cells.

Thirdly, avoid fast charging and discharging if you can. Fast chargers might seem convenient, but high currents will heat and degrade a battery faster than a slow trickle charge. The same goes for high discharge rates; power-hungry applications and full-throttle action in the vehicle world are not good for your battery, and will reduce its lifespan. If possible, get hold of an old-school, 1A slow charger for phones, and use that unless you really need to top up fast.

Nine key tips for extending the life of lithium-ion batteries
Nine key tips for extending the life of lithium-ion batteries

Finally, avoid using or storing lithium-ion batteries in moist environments, and "avoid mechanical damage such as punctures," which would seem fairly self-explanatory.

In short, watch the temperature, charge and discharge slowly, don't leave batteries on the charger, and try not to go above 80 percent or below 20 percent unless you need to. Not only will your batteries last longer, you won't have to replace them as often – and that's great for the planet in a number of ways.

The study was published in the Journal of Energy Storage.

Source: University of Michigan, Ann Arbor

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13 comments
sidmehta
Confused about discharging to 20% and charging to only 80%. Read often that Li-Ion batteries must be discharged fully and charged fully to maintain their capacities. Which is correct?
paul314
So basically don't use your batteries in a way that's convenient for you? This is like the people who have to change their names to fit computerized forms.

One of the things I wonder about here is what "0%" and "100%" actually mean when most battery charging is controlled by complex management circuits, and levels are displayed by a piece of software that recalibrates itself on an ongoing basis. Are our phones actually charging to 100% of their electrochemical capacity, or just to 100% of the 80% that their software considers the upper limit for longer life? Same on the bottom side: it's pretty clear that "0%" isn't actually empty, because a phone or other device typically still has enough juice to display a message saying it has no power left...

(A family member had a phone that wouldn't charge above "30%" as indicated on the display, even though battery life indicated a much higher level. The phone died before the promised software update to display the "right" number.)
Aross
Interesting article but hope that they don't use lithium-ion batteries in electric cars. If they do then those of us living in Canada without a garage to store our electric cars are screwed as far as charging goes within the optimum temperature range. Now we will not only have to plug in to charge but also run a battery heater/cooler to be in the optimum range. With a local temperature range of from -30c to over +95 I see a large portion of any savings in operating cost disappearing.
buzzclick
I came here hoping to learn something new since I've done my own research. It makes sense to use the cells optimally. Paul314 asks good questions. Li-ion batteries are almost always designed with a BMS (battery management system) circuit that is either part of the batt pack or incorporated into the phone/car/tool/gadget, and its job is to keep things humming at proper levels. I am surprised though to see that automotive batteries should not be charged below 50deg F/10deg C since so many electric cars in my neck of the woods are being used in the winter at well below that, and not all are kept in indoor garages. Of course, if you plug it in at the end of your day the batteries will be within that temp range. Extremes and fast charging means a shorter life span. Milwaukee has a charger, fast charger, and recently, a supercharger, for those who can't be bothered to wait.
mark00
Tesla owner here. One can argue the precise specifics, but IMHO the author got all this right and frankly his advice is fairly well accepted at this point. KInd of like saying brushing your teeth is a good idea (it is). As Elon Musk pointed out, you might be able to do a tiny bit better by charging to less then 80%, but it is "not worth it." Setting the default maximum State of Charge in a Tesla to 80% for everyday driving is super easy with an icon that your finger slides left and right. Similar settings for cell phones and other devices would help a lot.

sidmehta, the infamous memory effect generally does not apply to lithium ion batteries but does apply to at least some NiMH batteries, which have a totally different chemistry.
Allen
Why don't or can't current smart phone batteries be set to charge only up to 80% at night instead of always going up to 100%? Why don't cell phone manufacturers allow the option for fast or slow charge rates? Let me guess -- to do so would extend the batteries life cycle and decrease the need for you to buy an expensive replacement. Prove me wrong!
BlueOak
To the folks concerned about charging a phone to “100%” not being good for battery durability... how do you know a well designed smart phone Battery Management System is not already protecting you from that? ;-)....

The “100%” displayed on your phone is simply an analog to the battery voltage. It would be very easy for phone manufacturers to set 80 or 90% of actual fully charged voltage to display “100%”....

Given Apple’s recent method to charge to 80% earlier in the night, slowly, and then to top of the battery in the last 15-30 minutes before your wake cycle, it would not be surprising that they also set 80-90% actual charge to display “100%”. (Apple claims that last 20% is hardest in the battery and therefore delays it. GO BLUE!
neutrino23
This is good advice if you are charging individual AA or AAA cells. This probably doesn't apply to things like cell phones. iPhones specifically have built in intelligence to maintain a healthy battery. They don't overcharge. My iPhone 11 now shows a message at night when I put it on the charger that it will charge slowly overnight with a target of full charge at the time I usually wake up. This also applies to iPads and iMacs. Probably similar story for new versions of Android devices.
Douglas Rogers
I guess Robomow is out of luck!
JMS
I see opportunity to build in smart charging to the optimal conditions automatically. When recharge is done, the charger shuts down by itself. We should not have to be mindful and go unplug it. It should charge to 80%, unless the user toggles something to request a full charge. These no doubt are very easy to do today, and vendors can sell them as green features as well. Obvious, correct? No reason we should have to study "rules" and be ever mindful to obey them. Put the rules into the charge algorithm, so we can focus on bigger things.