Choosing The Right 18650 Battery – A Complete Guide.​

Choose a Quality Brand

The quality of 18650 cells is one of the most important factors to consider when purchasing one for your device or project. It’s important to remember that not all companies are created equal, and you’ll often discover that battery ratings are exaggerated by some. This is especially true when talking about the Chinese re-wrapping brands in general. For every company, the goal is to make as many battery sales as possible. But some companies have been known to inflate their ratings so that they look better than their competitors. Exaggerating battery parameters is against the law in many countries and might put consumers at risk if left unchecked. Fortunately, the battery market has a watchdog, the battery mooch, who conducts comprehensive testing and exposes firms that engage in illegal practices.

You can trust LG Chem, Molicel, Samsung, Sony Murata, and Panasonic Sanyo, five leading battery manufacturers, to deliver high-quality, consistent, and truthfully rated batteries. These companies have a lengthy history of tradition, principles, and standards that they must uphold. These companies’ manufacturer specifications are clearly recorded and have undergone extensive testing. In many cases, the battery will outperform the manufacturer’s claims.

The quality of certain other products, such Efest, Vapcell and Imren and MXJO, has increased dramatically over time. In fact, here at we have started stocking Vapcell, we have been impressed by the consistent performance of these cells, and battery mooch seems to agree with his testing of their cells too!

Other obscure brands have exaggerated ratings of all types. There wasn’t a single 18650 lithium-ion battery with a capacity of more than 3600mAh or a discharge rating of 35A from a reputable brand in 2022. In fact, due to the chemistry of these batteries, the higher the discharge rating, the lower the capacity. In the event that you come across an 18650 battery advertised with specifications higher than those listed above, it’s too good to be true and you proceed with caution. It’s almost certain to be inaccurate and misleading. A final thought, if these companies are prepared to make false claims about the cells and their performance, can they be trusted to have no cut corners on safety?

Finding the right size

When it comes to battery size, various devices require different types of cells. Our chart below displays the typical sizes we offer and includes the corresponding button top options. It’s crucial to determine whether you require a button top or not, as the sizes vary.

A comparison of 21700, 18650, 18350 cells sizes with and without button topsΒ 

Selecting the right Battery Capacity

Everyone would pick the biggest battery if they could have a choice. We measure capacity in milliampere-hours (mAh), and this informs us how many milliamps we can draw from the battery for how many hours. The only problem is that increasing capacity degrades the current rating (CDR). With only so much space within each cell, you’re forced to select between a high capacity battery or one that can deliver more current. This LG HB6 only has 1500mAh of battery capacity but has a 30A CDR (current draw rating). The Panasonic NCR18650B, on the other hand, has a CDR of only 4.9A and a 3400mAh capacity.

Some batteries, such the Samsung 25R, LG HG2, and Samsung 30Q, are able to strike a good balance between capacity and current rating. A good balance of capacity and current can be found in all three of the batteries listed above.

Continuous Discharge Rating (CDR)

When it comes to choosing a battery, this is unquestionably the most critical factor to keep in mind. It is important to know how much current your device needs before purchasing a battery. A battery that has a lower current rating than what you require will overheat because it is working harder than it can handle. When it comes to battery current ratings, you should be familiar with two terms. These are: continuous discharge rating (CDR) and pulse discharge rating (Pulse).

This is the maximum current that can be safely discharged from the battery on a continuous basis without causing damage to it. Pushing a battery past its breaking point increases the likelihood of it failing.

Pulse (Burst) Rating:
A battery’s pulse rating refers to the highest discharge current it can withstand for a brief time before being damaged or losing capacity.

We don’t use any pulse ratings since pulsing a battery has too many variables to compare two batteries effectively, such as pulse length, rest time between pulses, and battery temperature. We utilise the CDR rating for these reasons, which is the maximum current rating at which the battery may be safely discharged without overheating or destroying the cell.

Operating Temperature

The operating temperature of your battery is a warning indicator that it is being pushed too hard if it is regularly reaching a high temperature and becoming heated. It’s safe to say that a battery that’s constantly running hot will degrade faster than one that’s cool. High temperature lithium ion batteries have the potential for venting and/or bursting, which increases the danger. A higher CDR battery rating is something to keep in mind when purchasing.

Flat Top vs Button Top 18650 Batteries

There are two types of batteries available: Flat top and Button Top. Figure out which one you need before buying one. The battery’s positive terminal is referred to as the “+” end here. It is possible that a button top battery will not fit in a device that requires a flat top battery because of the protruding surface. If your gadget requires a button top battery, a flat top battery may appear to be too short.

18650 Battery Chemistry

When shopping for an 18650 battery, most people aren’t concerned with the chemistry of the battery. Brand, Capacity, Discharge Rating, Voltage, and Temperature should all be considered while purchasing a battery. We’ve ranked them from least volatile to most volatile, so you can see which chemistry mixes are the most flammable.

Common Battery Chemistry

LFP (lithium-iron-phosphate) – Least Volatile
LMO (lithium-manganese-oxide)
NMC (nickel-manganese-cobalt)
NCA (nickel-cobalt-aluminum)
LCO (lithium-cobalt-oxide) LiPo – Most Volatile