How long does an 18650 battery last?

One of the most common questions we receive from our customers is about the lifespan of 18650 batteries and how long they can be expected to last. Of course, with so many applications that they’re used in - some more frequently than others - it would be impossible to give an accurate answer. However, what we can do is give you guys an overview of what affects the lifespan of an 18650 battery. This way you can provide it with the best maintenance possible!

There are really three key features that impact the duration for which you’ll be able to use an 18650 battery; age, capacity and charge cycles. Here’s how they impact performance.

18650 Battery Age
Our younger customers might not know it, but for those of us who are a little more experienced, we all know the perils of growing old. What was once a quick sprint to the ball in Sunday league football is now a hard, laboured pursuit. The reason? Age. It’s the same for batteries. We all know that old batteries aren’t as good as new ones.

You’d be correct in thinking extensive use takes its toll on cells, but so does time in storage. There’s even certain conditions that you’d be wise to meet in order to mitigate any deterioration during this time. Definitely make sure they’re stored inline with the manufacturers recommendations for temperature and humidity. Also, especially in the case of new cells, consider storing them at 50% of their charge. It would be reasonable to expect them to retain the majority of their capacity when recharged thereafter. Like any electrical device though, performance and capacity will reduce over time.

So just because batteries are old, it doesn’t make them unusable. Provided you have given them the best possible storage environment, they still have the capacity to serve you well.

18650 Battery Capacity
Ah, capacity. Literally “Ah”, as amp hours (Ah), milliamp hours (mAh) or Watt hours (Wh) are all units used to measure the energy contained within a cell, battery or battery pack. Usually, this is the most efficient way of working out how long a battery will last in comparison to others. When comparing batteries, make sure to take into account both the load and the constant discharge of each as, whilst one model might be higher on the first one, it doesn't mean it will last longer if it has a lower figure for the second.

It’s important to be mindful of the way in which you’re asking your batteries to perform as, if you’re running them at or beyond their limit, their internal chemistry is likely to be compromised. Therefore it is very important to get it right the first time when selecting a cell for the job at hand.

As mentioned previously, capacity naturally decreases with both use and the age of the battery. One of our most popular range of products - and a great way to monitor this - is the XTAR chargers. For example, the Xtar VC4 provides a real-time OLED with analogue style gauges, giving you information on the voltage, charging amps and milliamp hours read-out. Handy piece of kit right?  It’s a good way to keep an eye on the health of the battery and know when it’s time to get a replacement.

18650 Battery Charge Cycles
Let’s do a bit of homework to start with - what is a cycle? Well, it is when a battery is fully charged then fully discharged down to the lower voltage limit at the maximum discharge rating. This then relates to the “cycle life”, which is the number of complete charge and discharge cycles that a battery is able to support before it is only able to deliver 80% or less of its original capacity. 

Don’t worry though, it is possible to extend cycle life.

As we mentioned earlier, if you’re constantly running your battery to its limit or beyond, it’s naturally going to wear out quicker. By giving it space to breathe and perform, you’re much more likely to help prolong its lifespan. How can you do this though?

Consider only ever running your battery at 80% of its maximum discharge capacity, helping you to extend the number of cycles you can get out of it and maintain its capacity for a longer period of time. You can even give your battery a bit of tender love and care during the recharging process, opting to charge it at a lower amp than recommended, thus improving the cycle life.

On the contrary, it doesn’t take a rocket scientist to work out that you can have a negative impact on the cycle life, especially if you’re smashing the life out of your battery!

Running it to its limits will only put it under huge strain, destroying the internal chemistry and having a substantial impact on it’s capacity. It’ll also lose its ability to hold a charge too. Not ideal.

So there you go, that's our answer to the common question "how long does an 18650 battery last?". Whilst it’s impossible to give a scientifically accurate, definitive answer, we can provide the information to give you the best possible chance at maximising the life of your battery.

With a bit of love and care, you can certainly make their performance go further, helping out your bank balance in the process!