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Akkuguide

Introduction:

Until the early 1990s, airsoft guns were either gas or spring powered. Then, after seven years of development, Tokyo Marui of Japan introduced the first electrically powered airsoft weapon to the market in the form of the French FAMAS assault rifle. From that point on, the triumph of AEGs was unstoppable

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First, a short excursion into the German Weapons Act (WaffG): due to the current legal situation, electrically powered airsoft weapons in Germany fall into two categories: all airsoft weapons with an energy <0.5 joules are toys in the sense of the law and are therefore allowed to shoot fully automatic or in bursts of fire, in addition to the single-shot function (SEMI). Therefore, the term "AEG" (when talking about electric airsoft guns), which is usually in general use abroad, is usually only applied to models under 0.5 joules in Germany
The second category represents the electrically operated Airsoft weapons with an energy >0.5 joules (up to max. 7.5 joules). These are "free weapons" in the sense of the WaffG and may only be acquired from a minimum age of 18 years. In addition, the firing function of this type of models is regulated to the single shot. Therefore, these models are called S-AEGs, i.e. Semi-Automatic-Electric-Guns. This term is used almost exclusively in Germany, as most European countries do not have such a regulation

After this little excursion into the world of the legal, we want to come back to the actual topic: Batteries in Airsoft. One of the most frequently asked questions is "Which battery can I use in my Airsoft"?
In order to be able to give a technically correct answer to this question, this guide is intended to be an aid in selecting the appropriate battery. In addition, it also contains further information regarding storage, where there are some things to consider, especially with LiPo batteries, as well as the charging process

Outline:

1. Basics
2. Connectors
3. Battery types (NiCd, MiMh, LiIon, LiFePo, LiPo)
4. Types
5. Charging & Storage
a. Chargers
b. Charging times
c. Safe storage
6. Myth Memory Effect
7. Conclusion

1. Basics:

Each battery has three values that describe its performance. These are usually noted directly on the battery as a sticker or can be taken from the item description in the store:

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Voltage, expressed in volts (V), can be referred to as the "force component." The higher the voltage of a battery, the faster a firing process in a (S)AEG will go through. In principle, this also allows the use of stronger springs, but the performance of the motor must also be taken into account here (it can reach its performance limit with too strong springs and thus heats up)
The capacity, measured in milliampere hours (mAh), simply states how much current can be stored in the battery itself and thus provides information about the service life. The higher the value, the longer the battery can be used until it has to be recharged. The capacity is limited by the size of the cells and this varies depending on the type of battery: a LiPo cell is thus significantly smaller than a NiMh cell, with the same capacity
The discharge current, indicated by the C coefficient (C), represents the remaining capacity and the time in which a constant discharge current can be delivered. LiPos for airsoft should have at least a discharge current of 25C, so that they can withstand the current peaks when the system is turned on. It should also be noted that the C-value on the battery is by no means the nominal value for the charge current (more on this under point 5)
Today, there is a gigantic range of batteries, so it can be difficult to choose the right model
Besides the pure battery choice, it also plays a role whether the system of my (S)AEG is suitable for the corresponding battery at all
So it should be checked in advance which batteries I can use in my Airsoft, especially if a MOSFET or an EFCS is installed
Outdated systems, which are equipped exclusively with a normal switch unit, can in principle be operated with any type of battery, but it should be noted: the higher the voltage of the battery used, the higher the wear in the form of carbonization, on the contacts of the switch unit

2. Connectors:

For a long time, the so-called Tamiya connectors were installed on airsoft guns as standard. These are available in a small (mostly light green) and a large version (mostly white). Originally these connectors come from the model making/RC area. For NiCd and NiMh batteries, these are perfectly adequate in terms of load. Here, the cables are "crimped" (squeezed) onto metal pins with special pliers, which are then inserted into a plastic socket via a barb. This design is very susceptible to interference, especially if the plugs are pulled improperly on the cable
Meanwhile, numerous models already have the so-called DEAN/T connector ex works. This is characterized on the one hand by a more compact design (this makes it easier to stow the battery when there is little space in the gun) and has a significantly lower internal resistance, because these plugs are soldered directly to the cables, which in turn is less susceptible to interference. The DEAN/T connector is also available in a smaller "mini-DEAN" design. This is mainly used with AEPs and the corresponding LiPo batteries, as there is only little space available to accommodate the battery and cables due to the limited battery space
LiPo batteries also have a balancer connection (JST-EH connector) in addition to the pure battery connection. This is also connected to the charger during the charging process and serves to charge each cell evenly

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3. Battery types:

NiCd (nickel cadmium) rechargeable batteries are the oldest rechargeable batteries used in (S)AEGs and are no longer available in the EU since December 31, 2016 due to the incorporation of cadmium, which is highly hazardous to the environment
The battery cell of a NiCd battery has a voltage of 1.2V, in the state of charge the voltage should be between 1.4 and 1.65V. The final discharge voltage at about 0.8 to 0.9V. These values should be observed especially during charging and discharging processes, since overcharging (>1.65V per cell) or deep discharging (<0.8V per cell) can damage the battery

NiCd batteries are characterized on the one hand by the possibility of delivering very high currents (due to very low internal resistance), are insensitive to cold and have a relatively low self-discharge. The disadvantage is, as with NiMh batteries, the so-called "memory effect": here the NiCd battery seems to store the last charge level of its cells. This means practically: if you use the capacity of the NiCd battery permanently only up to half, the battery stores this for itself and can be increasingly charged only up to half. The capacity of a NiCd battery is thus lost somewhat with each charging process
In addition, it should be noted that NiCd batteries are inefficient due to the delivery of high current flows and at the same time have a very large design, thus for some models alone are not usable. NiMh (nickel metal hydride) batteries are similar to NiCd batteries (1.2V per cell), but contain nickel metal hydride instead of the heavy metal cadmium
This has, apart from the environmental aspect, another advantage: with the same volume, a higher capacity results (example: NiCd battery with the dimensions (L x W x H) 15 x 3 x 2 cm has 1000mAh, a NiMh battery comes to 1500mAh)

The self-discharge of NiMh batteries is higher than that of NiCd batteries. It is about 30% per month, but since 2006 there are also low self-discharge batteries, which then reach the level of NiCD batteries of about 15% per month. Another disadvantage is the higher internal resistance, which is noticeable in the slower response of an (S)AEG. However, this disadvantage can be compensated by increasing the number of cells and thus the voltage, but this also results in an increase in the size of the battery pack
NiMh batteries are more temperature-sensitive than NiCd cells, which can be used at sub-zero temperatures without hesitation, while NiMh batteries should not be charged or used below freezing point. Temperatures beyond 30° can also harm the NiMh battery
NiMh batteries should not be charged too fast, otherwise they will heat up too much, also NiMh batteries are more sensitive than NiCd batteries regarding overcharging and deep discharging
LiIon (Lithium Ion) batteries have a much higher internal resistance than NiMH and NiCd batteries and are therefore not suitable for Airsoft, because these batteries would be damaged in a relatively short time due to the high current flow when starting the system (turning on the motor)
LiFePo (Lithium Iron Phosphate) batteries contain a liquid electrolyte and have a significantly lower internal resistance than LiIon batteries, which predestines them for high current applications such as in airsoft. They are an optimal compromise between NiMh and LiPo batteries
One of the biggest advantages is the possibility to use high charging currents and thus to reduce the charging time considerably: 3C are easily possible (with LiPo max. 1C), so that e.g. a 1000mAh LiFePo can be charged to 95% of its capacity in 20-30 minutes. Furthermore, LiFePo batteries have a long lifetime compared to NiCd and NiMh (measured by the number of charge cycles). Following this, it should be mentioned that LiFePo batteries have no memory effect. The self-discharge is about 3-5% per month, so the batteries can be stored in any state (except fully charged and fully discharged, optimal is 70% of capacity)
A disadvantage is the temperature sensitivity of LiFePo batteries: the colder, the more voltage as well as capacity are affected

The biggest disadvantage of LiFePos, however, is the low energy density: the batteries are larger compared to e.g. LiPos (with the same power) which limits the use with airsoft weapons somewhat. Due to the nominal voltage of 3.3V per cell, it is also possible that a 9.9V LiFePo battery in an airsoft weapon is too weak, but the next higher voltage of 13.2V is too high for the MOSFET/EFCS (for airsoft weapons with installed EFC system, check in advance whether this is designed for LiFePo batteries at all)
LiPo (Lithium Polymer) batteries are the further development of the LiIon batteries and nowadays the standard in the airsoft area. In contrast to the LiIon batteries, a solid electrolyte is used here, which means that a housing around the battery is no longer necessary. This not only makes the batteries lightweight, but also allows them to be manufactured in almost any shape

A cell of a LiPo battery has a rated voltage of 3.7V per cell, up to 4.2V per cell when fully charged, and at 3.7V/cell in the storage state
LiPos have the advantage of being able to provide a high voltage consistently over a long period of time. While with NiMh and NiCd cells the voltage drops relatively quickly, with LiPo cells it is almost constant until the end. This also applies to the self-discharge, which is very low in LiPo batteries
The big disadvantage of the cells is their sensitivity, both to overcharge (>4.3V/cell) and deep discharge (<3.2V/cell), as well as to heat, cold, shocks and short circuits. As temperature decreases, the internal resistance of the cells increases
Since differently charged cells can quickly destroy a LiPo battery, they are usually equipped with a balancer connector, which allows high-quality chargers to distribute the charging current evenly to the cells. Charging the battery without a balancer is strongly discouraged! An incorrectly charged battery can be easily recognized by the fact that it changes its shape and inflates over time
Since LiPo cells, unlike other battery types, do not have a housing, a slight coking of the battery due to overcharging can lead to a serious fire due to the unhindered supply of fresh air. It is therefore advisable to charge LiPo batteries in a special charging bag made of fireproof material and also on a fireproof surface
To prevent a deep discharge, there are so-called LiPo - Warner, which monitor the voltage of the battery and switch off the battery at a cell power of less than 2.9V and give an audible or visual signal to the user to prevent damage to the battery. These are simply plugged into the balancer connector of the battery and monitor the voltage of the battery

In airsoft guns with an EFC system, such a LiPo - Warner is now mostly no longer necessary, because these systems themselves have a shutdown function and detect when the voltage of the battery falls below a certain value. In the case of the BEGADI CORE EFCS this is signaled by a short vibration of the motor, in other systems this function can be set individually, from when the system should emit a warning signal
A LiPo cell should be charged with 3.7 - 3.9V per cell during longer storage, the maximum voltage of 4.2V per cell must not be exceeded
LiPo batteries should be charged with a maximum of 1C, which means that a 1200mAh battery should be charged with a maximum of 1.2A charge current - less is always better and by no means worse. Thus, the battery described above can also be charged with 0.6A, only the duration of the charging process will be longer
This also shows how important it is to use an appropriate charger for charging a LiPo battery in order to prevent overcharging and, in the worst case, an explosion of the battery
A LiPo is NEVER to be charged directly via a power supply unit at the socket!

If the following safety rules are observed, LiPos are no more dangerous than conventional batteries:

use a charging bag made of fireproof material and charge on a fireproof surface (e.g. a clay tray)
Charge battery with maximum 1C (1A) - less is more gentle
Charging temperature should be between 0 and 45°C
discharge temperature should be between -20 and 60°C
below 0°C LiPos should not be used - internal resistance increases
Charge only with high quality chargers with balancer
if necessary: use LiPo - warner to protect the battery from deep discharge
Protect battery from shocks (e.g. cushion battery compartment in weapon)
use high-current connectors (DEAN/T connector or XT60 connector)

4. Construction types:

In addition to the battery types, you can also distinguish between different battery designs
While NiCd and NiMh are less variable in their design, LiPo batteries are available in almost all designs, which makes them even more suitable for airsoft
Theoretically, you can connect any type of battery to any airsoft and operate it with it. However, you should use the battery that best fits your model and can be stowed, because who wants the battery dangling around the side of the gun during play
Therefore, it is worthwhile to roughly measure the battery space in your model and thus make the search for the right LiPo. A little tip: you should always allow for a little tolerance when measuring, since the connections and cables also have to be stowed in addition to the battery.

In the following picture we show the currently most common designs of LiPo batteries for the airsoft sector:

Single Stick LiPo (short) - can be accommodated directly in the stock tube on M4 models, but will also fit AKs
Single Stick LiPo (long) - due to narrower, but longer design ideal for AKs
Triple Stick LiPo - ideal for M4 models with SOPMOD/Crane Stock
Block/Mini Type LiPo - suitable for models with battery accommodation in a fixed shaft or for G36 models
AEP LiPo - used almost exclusively with AEPs or for running electric HighCaps or HPA engines

5. Charging & Storage:

The question of the right charger could be answered in an extra guide, because the selection here has also grown enormously in the meantime
To date, some models already come with a battery and a simple charger included. These are mostly designed for a first test of the airsoft, but for the lasting fun of playing you should fall back on high-quality models
This has several reasons: firstly, these simple charging cables (because chargers are usually not) do not have any shutdown function, i.e. in case of inattention or incorrect calculation of the charging time, it can quickly come to overcharging. Furthermore, these models do not have a discharge function, for example, to bring a LiPo in the so-called storage mode (about 70% of maximum capacity)
Furthermore, these charging cables do not have a balancer function, which causes lasting damage to a LiPo and makes it unusable in the short term

Therefore, it is advisable to use a charger that, in addition to the above functions, also has memory functions, i.e. you can set up charging programs for your different batteries and save them. In addition, these chargers have functions such as

automatic switch-off when battery is fully charged = charging time is not applicable
Adjustment of the charging current (= how fast will my battery be charged)
Balancer connection for LiPo etc.
Storage mode function
Cycle function (e.g. for NiMh batteries)

The purchase of such a charger may seem expensive at first, but it pays off quickly because of the above mentioned points, which contribute significantly to the safety and longevity of a battery. An appropriate charger costs between

If you can store NiCd and NiMh batteries openly without hesitation, this is much different, especially with LiPo batteries. Due to the materials used in a LiPo battery, chemical reactions can occur during charging or due to damage to the interior, which leads to the LiPo inflating, toxic fumes escaping and in the worst case catching fire or even exploding. To minimize the extent of a fire etc. in extreme cases, LiPo batteries should be charged, transported and stored in a LiPo bag
These LiPo - Bags are made of a flame retardant material and are a thankful investment in the safe storage of batteries. They come in different shapes and sizes, according to your needs

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6. Myth Memory Effect:

The so-called memory effect was discovered by NASA employees. They noticed that a NiCd battery, which they had installed in a satellite, only had as much capacity after an orbit as had been used and recharged during the previous orbit
However, this was an old type of NiCd battery, with sintered electrodes. This design was used until the 90's and in the meantime this effect is not as high as it was back then, even with NiCd batteries
The memory effect can be reversed by repeated charging and discharging up to the final discharge voltage (no deep discharge) (so-called cycling), but this is of course at the expense of the usable charge cycles
NiMh batteries have no memory effect, but incomplete discharging before recharging can lead to the so-called battery inertia effect. This does not reduce the capacity, but the voltage delivered during discharging. Just like the memory effect, the battery inertia effect can be reversed by charging and discharging several times, again at the expense of the usable charge cycles
Lithium batteries use completely different materials and are therefore spared both phenomena. Corresponding regeneration programs or charging techniques should therefore never be used with lithium batteries, as they can only harm the battery and in no case benefit it!

7. Conclusion:

In conclusion, it can be clearly said that LiPo batteries are the first choice for airsoft. They are characterized by their constant performance, versatile design and low self-discharge. Charging should be done with an appropriate charger and storage in a fireproof container, in addition to the LiPo bag
If you still have questions regarding the right choice of battery or the like, you can reach us as usual by e-mail - our customer support will take care of your request as soon as possible

Status: 06/2022