Begadi Guides

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Begadi Battery Guide
Introduction: Until 1991 airsoft guns were powered by gas or spring, when Tokio Marui, after 7 years of development, introduced the first AEG (automatic electric gun), the famas. AEGs displaced the existing guns and quickly become the standard in airsoft gaming. In germany the guns were converted to shoot only semi automatic, because of the existing gun law. The term SAEG (semi automatic electric gun) was established for these converted guns.
Today many variations of SAEGs are offered and the batteries also developed in the past years. With this guide you should get the basic knowledge about existing battery types and how to choose the right one for your application.



A 7,4V 1200mAh LiPo battery (top) in comparison to a 9,6V 1600mAh NiMh battery (bottom).

Caused by the high discharge current of LiPo batteries, both types run a gearbox at nearly the same speed, though the NiMh battery has 2,2V less current than the LiPo. Another advantage of the LiPos ist the small size. Basics:

The power of every battery is measured in three values.

The current is measured in Volt (V). The higher the value, the faster the gearbox can run and stronger springs can be winded up. NiCd and NiMh batteries with 8,4V are often sold together with SAEGs, but for permanent semi automatic fire these batteries are too weak. This results in a higher risk for gearbox jams and therefore they should not be used.

The capacity, measured in milliampere hours (mAh), shows how long the battery can be used without recharging. The capacity is restricted by the manufactured size of the cells.

The discharge current, shown in the c-coefficient (C), stands for the residual capacity and the time in which a constant discharge current can be delivered. 25C is the minimum discharge current LiPo batteries should be able to offer.



A 7,4V 1200mAh LiPo battery in a real sword type 56-2. Due to the folding stock in this SAEG there is not enough space for big batteries. The small LiPos are ideal for guns with limited space.

Battery Types:

NiCd (Nickel Cadmium) these are the oldest batteries used in airsoft guns, due to the high-grade hazardous cadmium they are no longer allowed to be sold within the EU since 31.12.2016.

NiMh (Nickel Metal Hydride) have the same structure as NiCd batteries, but instead of the heavy metal cadmium they consist of nickel metal hydride. NiMh is not only environmental friendly, it offers a higher capacity with the same size. The self discharge on NiMh batteries is with 30% per month higher than on NiCd. Since 2006 there are NiMh batteries with lower self discharge which are almost equal to NiCd batteries (15% per month).
Another disadvantage of NiMh batteries is the high internal resistance, which causes a slower response behavior on your gun than NiCd batteries. By raising the number of cells and therefore the current this disadvantage can be equalized.
NiMh batteries are more temperature sensitive than NiCd cells, which can be used under sub-zero temperatures without any restrictions. NiMh should not be loaded or used under the freezing point. Temperatures above 30° celsius can also damage the battery, therefore they should not be loaded to fast, because they are heating up to much. Overcharge and deeply discharge are another point in which NiMh batteries are more sensitive than NiCd.



A 9,6V 1600mAh NiMh battery in “triple stick” design, this type can optimally be used in crane stocks. Due to the high amount of cells, in this case 8, NiMh batteries can be put together in many different variations so the available space can be used to its full capacity, but the size is always limited to the size of the cells that are used.

LiIon (Lithium Ion) have a clearly higher inner resistance than NiMh and NiCd batteries and therefore are not suitable for airsoft applications.



This 7,4V 1200mAh LiPo is a extra small model, optimally designed for AK series where the battery can only be put under the top cover.

LiPo (Lithium Polymer) batteries are the further development of LiIon batteries and today the standard in airsoft applications. Compared to LiIon batteries LiPos use a solid electrolyte, where a casing around the battery is no longer needed. Therefore the batteries are lighter and can be produced in arbitrary designs.
LiPos can offer a high amount of current consistent over a long period of time, while NiMh and NiCd cells de-energize relatively fast, LiPos offer nearly the same current consistently until the end.
The biggest disadvantage of LiPos is the sensitivity on overcharge, deeply discharge, heat, low temperatures, shocks and short-circuits. With sinking temperature the inner resistance rises. Different loaded cells can destroy the battery, so they are equipped with a balancer connector. High-class chargers are able to distribute the current over the single cells. Charging an LiPo without balancer is highly disadvised.
Due to the not existing casing on LiPo cells a small burn caused by over charging can easily become a big fire because of the direct air supply. Therefore loading LiPos is advised only in a special fire-proof bag and additonal on fire-proof ground.
To prevent from deeply discharge you can use a LiPo saver, which monitors the current of the battery and switches it off, when the current of one single cell is under 2,9V. The LiPo saver also gives an optical or acoustical signal to the user to prevent the battery from damage.



A LiPo-Saver, on the left you can see the balance cable from the battery. The negative pole (black cable) on batteries with only 2 cells (e.g. 7,4V LiPo) must be plugged in the "COM-Port" of the LiPo Saver. The BAT3 pin is not in use then. This saver not only gives optical and accoustical alert, when the current is too low, but also shows the actual capacity of the plugged in battery.

The LiPo saver connects easily to the Balancer plug of the battery, so they can monitor each cell separately. On longer storage a LiPo cells should be loaded between 3,7 – 3,9V, the maximum current of 4,2V should not be exceeded. Loading should only be done with 1C, which means a 1200mAh battery should be loaded with 1,2A of charge rate which can be adjusted on the charger.
The usage of batteries with high current can affect internal parts of the gearbox like for e.g. the tappet plate or the switch assembly. To prevent these parts from damaging they should be replaced by reinforced ones. A MOSFET is a reasonable extension, you can read more about this in the mosfet guide.

When the following security rules are obeyed a LiPo is not more dangerous than a conventional battery.

• Always use a charging bag, made of fire-proof material on fire-proof surface
• Never charge the battery with more than 1C.
• Loading temperature should be between 0 and 45°C.
• Discharge temperature should be between -20 and 60°C.
• Do not use LiPos under the freezing point.
• Charge only on high-class chargers with balancer plug.
• Use a LiPo saver to prevent your battery from deeply discharge.
• To prevent the battery from downfall, pad it in the gun and fix it as good as possible, the padding can also serve as isolation against cold.
• Use high current plugs only (Dean or XT60-plugs)

LiFePo (Lithium Iron Phosphate) batteries use a liquid electrolyte and have a much lower inner resistance than LiIon batteries, which makes them perfect for high current applications, like airsoft. They are an optimal compromise between NiMh and LiPo batteries.
One of the biggest advantages of LiFePo batteries is the possibility to use high loading rates. 3C is no problem, some batteries can be charged to 95% of there capacity in 20-30 minutes. A balancer is not necessary but recommended. A high thermal load is not possible with LiFePo batteries, which makes them perfect for rough use.
The operational conditions lie between -45 and 70°C. All lithium batteries cause voltage dips under 5°C but these do not involve capacitance loss. The self discharge is around 3-5% per month, therefore the LiFePos can be stored in any condition, except fully charged or discharged.



Size comparison betwenn a LiFePo 9,9V 1100mAh (top) and a LiPo 11,1V 1300mAh (bottom).

The biggest disadvantage of LiFePos is the small energy density. The cells are much larger than LiPos, which limits the field of application in airsoft guns a little. The rated voltage of 3.3V per cell can make a 9.9V LiFePo battery to weak for the selected application and with the next higher possible voltage, which is 13,2V, the battery can already be to strong.

Myth Memory Effect:

The so called memory effect was discovered by NASA personnel. They determined that a NiCd battery which was installed in a satellite, only had as much capacity as it discharged and charged in one earth revolution. These NiCd batteries were an old design with sintered electrodes. This design was used until the 90s, but this effect on modern NiCd batteries is not as high as it was back then.
The memory effect can be reversed by charging and discharging the battery to the end point voltage, but this sets down the usable load cycles.

NiMh have no memory effect, but due to not fully discharge before charging the so called battery inertia effect can take place. This does not set down the capacity of the battery, but the emitted current. Just like the memory effect, the battery inertia effect can be reversed by charging and discharging cycles.

Lithium batteries use complete different materials than NiCd and NiMh batteries, both effects are not possible with them. Regeneration and maintenance techniques should never be used on Lithium batteries because they can only harm them.

Connectors:

Most airsoft guns are delivered with so called Tamiya connectors, which are available in small and big format. They come from the RC model building and are named after a famous model-building company which invented them. For NiCd and NiMh cells they are sufficient. The cables are crimped on metal pins which are plugged in a plastic socket. A fluke prohibits the pin from falling out.
This structure is accident sensitive especially when the connectors are improper pulled by the cables. On high current connectors the cables are soldered to the pins, which are permanently attached to the socket. Therefore they are less accident sensitive than the tamiya connectors and recommended to all airsoft applications.



Different connectors, from left to right: XT60 connector, DEAN connector (both capable of high currents), Tamiya small, Tamiya big (not capable of high currents and more accident sensitive)

When soldering a connector, you should remember that the heat which is transferred from the soldering iron to the cable can damage an attached cell !