Tuesday, May 24, 2011

Rechargeable 18650 Li-Ion Batteries

Li-ion batteries are the most advanced rechargeable batteries currently used in the consumer market. It is currently being used in many items including mobile phones, laptops, cameras and other mobile consumer electronics products. Its ability to store power and quick charge to full capacity makes it attractive for common and frequent use.

Li-ion usage has been steadily increasing in the past few years. Sales are increasing by 10% every year. Conversely, the prices of li-ion batteries have dropped from $4 per watt-hour to about $1.50 per watt-hour. With a lower price, more and more products are now using li-ion batteries. This in turn drives the price down even further.

One of the most economical formats of li-ion batteries is the 18650 format. Batteries with this format have the measurement of 18 X 65mm.

Choosing 18650 Li-Ion Rechargeable Batteries
It is not easy to choose the best rated li-ion 18650 batteries. There are a lot of factors that need to be taken into account. However, 18650 li-ion rechargeable batteries have a lot of advantages over other rechargeable batteries. These include:
  • No memory effect.
  • It is able to store more power.
  • It has built-in protection to extend its lifespan.
With other types of rechargeable batteries especially nickel cadmium, there is a serious problem called the memory effect. This happens when the battery is charged before it has fully discharged. This causes the battery to be ‘confused’ about its maximum possible charge. Subsequent charges will cause it to charge to a point lower than its maximum possible charge. This is known as the memory effect. In the long term, the battery will lose its capacity and will have to be replaced. This problem is not present with li-ion batteries. As a result, li-ion batteries last longer than its counterparts.

With a different chemistry used in li-ion batteries, the best rated li-ion 18650 batteries are able to store more power compared to other types of rechargeable batteries. This effectively means that li-ion batteries can provide power for a longer period of time.

A new feature found in the best rated li-ion 18650 batteries is the integrated printed circuit board (PCB) protection. This feature controls the voltage that goes in and out of the battery. It prevents under-voltage at 2.5V and over-voltage at 4.25V from happening. If voltage falls too low, it will cause the battery to over discharge. On the other hand, when voltage rises too much, it will cause the battery to overcharge. With the internal PCB protection, the issue of overcharging and over discharging will not happen anymore.

There are many different manufacturers of the best rated li-ion 18650 batteries. These include Ultrafire, Tenergy and Trustfire. The prices of li-ion 18650 batteries between these manufacturers vary. The price difference is mostly caused by extra features or capacities between one battery and another. Usually, the more expensive battery will have extra features such as thermal cut-off protection. Sometimes obtaining a more expensive battery can ensure a battery that is of better quality comparatively as well as a battery that has a longer lifespan.

Typical 18650 Li-Ion Rechargeable Batteries
Unfortunately, all the li-ion 18650 batteries produced by the manufacturers mentioned above have similar features. All Ultrafire, Tenergy and Trustfire li-ion batteries have the following characteristics:
  • Integrated PCB protection prevents batteries from over charging and over discharging.
  • The batteries can be charged more than 400 times.
  • The batteries come in a range of different storage levels.
Doing a search for li-ion rechargeable batteries with the 18650 size in Amazon.com provided information on the more popular choices. The Tenergy brand of li-ion rechargeable batteries seems to be more popular than the rechargeable Ultrafire 18650 batteries.

Tenergy li-ion 18650 rechargeable batteries can still maintain 90% of their initial charge even after 400 charges. It is expected that these batteries will last more than 500 charges. The rechargeable Ultrafire 18650 batteries, on the other hand, can only maintain about 85% of their initial charge after 400 charges.

With this in mind, it is clear that popular choices are made based on the features that differ from one battery to another. This can be due to the fact that a lot of the features are already very similar. As such, the battery that has that extra edge will be the more popular choice.

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