How do I choose the right 18650 battery?

This is a question we get asked time and time again here at Fogstar. Our team is always on hand to help with any questions or queries, but we thought it might be useful to tell you about a few fundamental differences which may help you decide which variant of 18650 battery to buy. 

One thing you may happen to notice is that, regardless of which variant you choose, all 18650 batteries are cylindrical in form, around 65mm in length and circa 18mm in diameter. Your 18650 battery will contain a negative and positive end and is complete with a safety-critical insulator and battery wrap. 

You’ll find 18650 batteries in a wide range of electronics, from video doorbells to cordless drills to vaping mods - but how can you identify the right 18650 battery to suit your requirements?  

Why are there so many different variants of 18650 battery? 

Your electronic devices and your individual requirements are all very different. 

Capacity (or energy density) is a key element when it comes to choosing the right 18650 batteries - this determines the amount of energy the battery holds and how long it disperses that energy for. Capacity is measured in Ah (ampere-hours) or mAh (milliamp-hours), the highest capacity 18650 battery that we offer is the Molicel M35A.

Do you require flat-top batteries or button-top 18650 batteries? 

It really depends on the device that you’re using. 18650 batteries produced by the large OE manufacturers are often made in flat top form. As you can probably guess from the name, the top is flat and requires a spring or protruding component facing out of the driver in order to make contact. If your device has such features, it’ll likely require a flat top battery. 

An increasing amount of devices nowadays require an 18650 battery with a button top. This is where the plus pole is raised above the rest of the battery. These are typically used in products such as video doorbells.

Do I need a protected or unprotected battery?

Like anything, there’s pro’s and con’s to using either. Protected batteries have a small electronic circuit integrated into the cell packaging. This protects the battery against a number of potential problems including overcharging, over-discharge, short circuiting and overheating. Many have a number of inbuilt functions used to protect against these issues. The advantage to using these batteries is that they’re less likely to blow-up and cause damage or injury.

Unprotected batteries, you won’t be surprised to hear, do not have the electronic circuit built into their cell packaging. As a result, there’s various advantages and disadvantages to be aware of. The absence of this protective measure means that these batteries can have more capacity and current capability than a protected cell. They’re also often much lower in price. However, there are considerable potential issues to be aware of. The risk of overheating, short circuiting and over-discharging is considerably higher as a result.

Our advice? Stick with protected cells. Yes, they’re more expensive but they’re also much safer. The additional cost is well worth the peace of mind

Ask the experts

It’s easy to get overwhelmed by the sheer amount of information across the internet when it comes to 18650 batteries. If you’ve read our other blogs, you will have seen that we always recommend using reputable suppliers who can provide you with the correct information and advice. When it comes to using batteries, safety is of the utmost importance. That’s why our team at Fogstar is always on-hand to answer any questions you may have. We’d be more than happy to help you to decide what would be the best 18650 battery for your device.