Airsoft Batteries - What the heck is NiMh?

We get a lot of questions on how to charge the batteries in your airsoft gun. We'll demystify that process and make it very easy for you. First, we will introduce you to the different types of rechargeable batteries. Specifically Nickel-Cadmium (NiCd) and Nickel-Metal Hydride (NiMh) that are sold for use in airsoft guns. Next, we'll talk about charger types and length of charge. We'll close the article with a few tips on extending the life of any rechargeable battery. Note: For the intent of this article we'll use the term milli-amps per hour (maH) to designate capacity. An example, a 850 maH battery can produce a constant power rate of 85 milli-amps over 10 hours. The higher the maH the higher the battery capacity; that means longer life on the airsoft field.

NiCd batteries are the most common and least expensive of the two technologies. Although cheap, rugged, and able to produce power for high torque needs (motors, etc), NiCd Batteries have two drawbacks: memory effect and the use of toxic materials (Cadmium). Memory effect occurs when a rechargeable battery is charged consistently at levels above recommended discharge level. Over time, the battery builds up a chemical "memory" that prevents fully charging the battery to it's rated capacity. Memory is not so much of a problem with newer NiCd Technology, but batteries should be fully-discharged before recharging to help prevent memory build-up. NiCd batteries are typically available in capacities under 1000mah.

This is the newer battery technology that we are starting to find widely available for airsoft guns. NiMh Batteries don't use highly toxic materials and have higher maH capacities than NiCd batteries. The downside of NiMh is cost; typically twice that of NiCd airsoft batteries. NiMh Batteries are also less resistant to "memory" build up. For airsoft, NiMh represents the better battery technology. NiMh Batteries also respond best to rapid chargers, and can be charged in as little as one hour without damaging the battery. NiMh Airsoft batteries come in all capacities up to 3600mah (the largest I know of for airsoft guns). There may be even higher capacities available as of this writing.

There are essentially three types of chargers: Wall/trickle chargers, timer chargers, and smart chargers. The wall/trickle charger typically ships with most airsoft guns and represents a cheap way to get up and running. The downside of wall chargers (also called dumb-chargers) is that they continue to provide charging current no matter what, and can cause damaging overcharging to the battery. They require constant supervision and knowledge of charge times. How long should you charge your airsoft battery? It all depends on battery capacity and charger output. Here is a great Airsoft battery calculator to determine charge time for a wall/trickle charger.

Timer chargers are like wall chargers, but typically have an adjustable timer to cut off current flow, preventing overcharging. However, it requires that the user know how long to charge the battery, and assumes the battery is properly discharged. You can use the Battery charge calculator to determine this.

The smart chargers represent the best technology for Airsoft Rechargeable batteries. Smart chargers have a sensor to determine when the battery has reached peak capacity and then cuts off current flow. This protects your batteries from overcharging and helps to ensure longer life. Most smart chargers even have a discharge function and the ability to trickle or rapid charge. Some of the better smart chargers allow you to adjust the charging current to decrease charging time. Just make sure that your smart charger is rated for your battery type (niCd or NiMh) or damage to your airsoft batteries could occur.

Additional airsoft battery care tips:

• After periods of non-use (weeks or months), fully charge your airsoft battery, as it will loose it's charge over time
• Avoid elevated temperatures. A charger should only raise the battery temperature for a short time at full charge, and then the battery should cool off. Heat is the main enemy of any rechargeable battery
• Always follow the manufacturer's guidelines for their battery's use, care, and storage.
• Finally, always recycle your used batteries to prevent their internal chemicals from ending up in our landfills (especially NiCd batteries).