Your guide to buying 18650 & 21700 batteries.

Starting at the beginning what is the difference between a 18650 battery and a 21700 battery? Well the answer is size, the first two digits being diameter and the last three being length the picture below should make it clear

18650 battery vs 21700 battery

Purchasing 18650 Batteries and their counterparts 21700 can be a mind field. The recent explosion in Lithium cells powering everything from Vapes to Trucks, means demand is huge and where their is demand there is an army of manufacturers and reatilers looking to serve that market with ever cheaper ‘options’ for consumers. With those low prices you see on auction sites like TradeMe, eBay and even some retailers, its almost impossible to compare apples with apples.

We would urge you to stop and think, what if these cells damaged my device? Is it worth it over a few dollars?

When buying 18650 & 21700 cells what do the performance numbers mean?

  1. Capacity: The capacity of a cell is measured in milliampere-hours (mAh) and indicates how much energy the battery can store. To determine the right capacity for your needs, you need to consider how much power your device requires and how long you need the battery to last between charges. For example, if you have a flashlight that requires 500mA of power and you want it to run for 4 hours, you would need a battery with a capacity of at least 2000mAh (500mA x 4 hours).
  2. Discharge Rate: The discharge rate of a cell is measured in amperes (A) and indicates how much current the battery can deliver. To determine the right discharge rate for your needs, you need to consider the maximum current draw of your device. For example, if you have a device that requires 10A of current, you would need a battery with a discharge rate of at least 10A to ensure that it can deliver the necessary power.

It’s important to note that different manufacturers may rate their 18650 cells differently, so it’s important to research and compare the specifications of different batteries before making a purchase. Additionally, it’s important to use batteries that are compatible with your device and to follow all safety precautions when handling and charging the batteries.

Often lower cost batteries, don’t perform as well as the figures state, after all its pretty cheap to print 3500mAh and 35A discharge on the side of a battery, its quite another to actually deliver that performance. Unreliable figures provide disappointing operation at best.

Here at we only stock genuine, batch tested cells from the likes of Molicel, Samsung, LG, Panasonic and Sony, ensuring our customers get high performing long lasting, safe, reliable batteries.

Our top 5 reasons to buy branded cells from a reputable retailer like
  1. Safety: Quality cells are designed and manufactured to meet specific safety standards, and they are less likely to fail or cause harm. Cheaper, low-quality cells may not have the same level of protection and could be more prone to overheating, venting, or even exploding.
  2. Performance: Brand name cells tend to have higher capacity and longer lifespan than lower quality cells. This means you will get more use out of them and won’t have to replace them as often.
  3. Compatibility: Cells are designed to work with specific devices and are built to specific specifications. Cheaper, lower-quality cells may not be compatible with your device, or they may not fit properly, which could cause damage to your device or reduce its performance.
  4. Reliability: Branded cells are more reliable and consistent in their performance. Cheaper, low-quality cells may have a higher failure rate, or they may not perform as well over time.
  5. Delivery: All our cells are in stock, if you can buy on the site, them we have them in Tauranga. Meaning you should have them in a couple of days, not waiting for them to ship from halfway around the world.

Overall, purchasing quality cells is important to ensure the safety, performance, compatibility, reliability, and warranty of your device. It is recommended to buy batteries from reputable manufacturers and distributors to ensure that you are getting authentic products that meet the required safety and performance standards.

We hope you have found this information useful, remember that flat top cells are unprotected against short circuiting and are considered components of other devices, great care should be taken when handling or carrying these batteries.