5 Trick to Keep 18650 Li-on Batteries Last Longer


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Perhaps after buying any new electronic device, whether it is smartphone or laptop, mini fan or flashlight, we all want to optimize the capacity of its batteries. 

Almost every electronic device nowdays uses 18650 batteries, a rechargeable type that may be very convenient. However, if we don’t use it properly, its life will be shorten quite fast.

If you are searching around looking for a way to protect the capacity of your batteries, the following tips may help:


  • Multiple-time charge instead of one-time charge:


Technically, your battery will be able to maintain its capacity better if you charge it frequently and avoid full discharge. For Lithium-ion batteries, you should charge them several times per day, for example, from 30% to 60%, or from 45% to 79%. That helps your battery cells to stay in an ideal condition for a long time.

On the other hand, if you just let your device fully discharged then try to recharge to 100% in once, the lifespan will be shorten. Look at the following table to see the difference between the number of cycle counts you can get before your batteries capacity declined by 30% based on the released percentage:

Percentage released Using cycles
100% 300 – 500
50% 1200 – 1500
25% 2000 – 2500
10% 3750 – 4700


  • Choose a suitable charger:


Have you ever noticed that the amount of time you need to fully charge a battery is different depending on the charger?

Yes, some charger having higher constant current (or constant voltage) will help to charge your device more quickly. However, it’s not good for your battery. Normally, lithium-ion batteries prefer slower charging. Because higher constant voltage will create a pressure for your batteries and reduce the ability to remain capacity in a long period of time, you should only choose chargers with lower constant current.

Nowadays, a lot of chargers are sold on the market with cheap price, but they can damage your battery if they don’t have proper specification. You need to choose a product that will prevent your battery from getting too hot, and make sure it stops charging when the cell reaches its peak voltage. Remember, pay attention to the algorithm of the unit.


  • Prevent too high temperature:


Hot temperature is one of the biggest enemies to the lifespan of 18650 batteries. If you don’t want your batteries to be replaced soon, then never put it in an elevated temperature.

Technically, after one year being used at 250C , a 18650 battery will still lose about 20% of the total original capacity. If the temperature is higher, for example, 600C, your batteries capacity will surely decline by 80%, and it’s very harmful for your electronic device.

However, it doesn’t mean that you should store lithium-ion batteries at extremely low temperature. Several bloggers on the internet said that it would be better to store a battery in the fridge. This is only true if the temperature in the fridge is set to a cool level. You should never try placing your batteries in a freezer or somewhere with too low temperature because it would weaken the charging ability of the cells.


  • Don’t let your batteries run out of capacity for too long:


During the period of usage or even storage, you had better remain the batteries’ capacity at around 40%. That’s the best level of capacity at which your device can be protected. 

At this percentage, your batteries will get an ideal status when the voltage is not too high and also not too low. This average capacity level don’t put any pressure on the cells and the batteries will gradually release the remaining percentage while waiting for a recharge.

Usually, lithium-ion battery is considered as exhausted if the voltage goes all the way down to 3V/cell. At 2,7V/cell, the battery will automatically be set to sleeping mode and lose its charging ability after a certain time. That’s the reason why you shouldn’t let it run out of capacity for too long.


  • Avoid charging through night:


It seems that most of us nowadays have a busy life. We are too busy (or even…too lazy) to charge our batteries during day-time. Lots of us often charge our phones or laptops at night, then we go to bed and just let the charger there until the next morning.

Well, if you have that habit, just give it up as soon as possible since it will seriously damage your batteries, and you will need to spend much money on buying new ones.

Actually, new technology helped to produce some chargers that can automatically stop after reaching the peak voltage or after the battery get 100% capacity. However, it’s still not good to charge overnight, especially to those who use a case or a leather cover since the case will accummulate the heat, which is not good at all for your batteries.

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