There are several factors in AEG batteries that need to be considered when selecting the right battery. One chief factor is the connection style. There are several types of connectors on the market, but the two most common, and the ones Elite Force uses, are Tamiya or Deans. Tamiya is extremely popular and very common. This is handy when locating a replacement battery at your local airsoft store or field. These connections work very well at efficiently transferring power from the battery to the device.
The Deans connector is becoming more popular and has a reputation of being extremely efficient in transferring power. Your AEG’s product description, box, and manual will all have the battery requirements listed.
AEG battery voltage needs to be considered. Some AEGs will have a specific voltage requirement that needs to be adhered to. Running too much voltage through the system can permanently damage the motor and gearbox. If the manual for your AEG calls for an 8.4 volt battery, install an 8.4 volt battery.
Some AEGs will have a Smart MOSFET that will allow flexibility in battery voltage choice as the MOSFET regulates the power consumption.
AR15 based AEGs tend to work well with nunchuck style batteries. HK MP5 and similar AEGs often take stick style batteries.
You will often see Discharge Rate listed as a battery specification. This simply refers to the ability of the battery to transfer its energy to the AEG. A “15C” discharge rate is ideal for most AEGs. Some higher draw AEGs like Elite Force’s EyeTrace equipped AEGs work well with 20C discharge rate batteries. The website product description, YouTube product reviews, the product manual and other sources will often spell out everything you need to know about the battery your AEG will require.