BATTERY INFORMATION!!!

Tech terms


mAh: MilliAmp Hours. A 1 mAh battery could last ~1 hour at at one milliAmp load.
Amps: Amperes, Current
Volts: Voltage
Ohms: Resistance
NiCd: Nickel Cadmium. A rechargeable battery chemistry.
NiMH: Nickel Metal-Hydride. A rechargeable battery chemistry.
LiIon: Lithium-Ion rechargeable chemisty (rare)
LiPoly: Lithium-polymer recheargeable chemsitry (expensive)


Battery Chemistries
There are 4 basic rechargeable batteries and 3 basic kinds of
non-rechargeable batteries. The non-rechargeables are carbon-zinc
("Heavy-Duty" or "cheap-o Non-alkaline"), alkaline, and Lithium.

Disposable Batteries
Carbon-zinc batteries are the cheapest cells you can get, they have a
fairly low capacity, but have a lower internal resistance than Alkaline
(still not as low as NiCd or NiMh), so they can deliver a higher
current than alkaline (hence the name "heavy duty").

Alkalines have a higher capacity than the carbon-zincs, but they have a
very very high internal resistance. These cells do not deliver high
currents well. Their high internal resistance causes them to "droop
down" under load. The nominal voltage for alkalines is 1.5 volts, but
the high internal resistance will cause them to droop down to less than
1.2 volts when heavily loaded. This is why higher powered devices (like
Electric Blow Backs and cheap R/C cars) will work better with NiCds or
NiMHs than with Alkalines. They are getting a higher voltage from the
rechargeable batteries since the alkalines (that are supposed to be 0.3
volts more per cell) are actually providing less voltage. Alkalines
also have a much different discharge graph than do the NiCds and NiMH.
Imagine a graph with cell voltage as the vertical axis and the percent
of charge remaining in the cell along the horizontal axis. Alkalines
have a steadily downward sloping curve. This means that alkalines put
out more voltage when they are fresh then when they are used up. They
will only provide their best performance when new, and lose some of
their power as they are used up.

The last type of non-rechargeable battery technology is the Lithium
cell. These batteries have the most capacity, and are the most
expensive. They are also lighter in weight and provide 1.7 volts per
cell. They can also provide a higher current than alkalines, but not as
much as the NiCd, NiMH or lead-acid. They are also very poor value for
your money.

Rechargeable Batteries

There are 4 principle chemistries of rechargeable batteries: NiCd, NiMH, Li-ion (Lithium Ion), Li-Poly, and lead-acid.

Li-ion (not to be confused with non-rechargeable Lithium cells) are the
newest type of rechargeable battery, and are the lightest that also
have the highest capacity. They are designed primarily for capacity.
These cells are very fragile. They cannot take the rough treatment of
an AEG (high currents). They also tend to explode if they are not
charged correctly. These cells are intended for use in high tech mobile
stuff, like laptops and cell phones.

LiPoly batteries are also coming into usage for airsoft -- while
voltage options remain limited, they are about the right size for
airsoft, and if you take care to not heat up the gel-packs, are an
extremely good high-ROF battery.

There is also the lead-acid type. This battery has two lead electrodes,
with sulfuric acid as an electrolyte. They come in two varieties, "wet"
cells (car batteries) that have liquid sulfuric acid (which can spill
all over the place...not good at all) and SLA (Sealed Lead Acid, or
"gel-cells") these are typically used in Uninterruptable Power Supplies
for computers. SLAs use sulfuric acid jelly and are sealed so they
cannot spill. These batteries are the toughest kind, readily providing
huge currents. They are also really cheap. The one main problem is that
they have lousy energy density and weight. Their energy density is
about on par with NiCd: a gel-cell and a NiCd of the same physical size
hold about the same mAh, but the LEAD-acid battery will be twice as
heavy. lead-acid batteries are 2 volts per cell, and typically come in
2 volt, 6 volt, 12 volt, and 24 volt sizes.

The 2 remaining rechargeable types of batteries are the ones usually
used in Airsoft: NiCd batteries, and NiMh batteries. Ni-Cd stands for
nickel cadmium, and NiMh stands for nickel metal-hydride. NiMH
batteries are a bit more expensive, but they have a higher capacity.
NiMH are a bit more difficult to charge than NiCd, so make sure your
charger is specified to handle NiMH if you use those type of cells.
NiMH also have a higher rate of self discharge. These type of batteries
will drain all by themselves if you just let them sit there. NiMH self
discharges by about 2-3% a day, while NiCd discharges by about 1% a
day. A full battery will be practically empty after sitting on the
shelf for about a month.

The common perception is that a NiMh battery will last longer, but wont
have the voltage of a NiCd with the equivalent number of cells. This is
not always true. Older NiMh batteries usually were at a lower voltage
per cell compared to Ni-Cds. The more recently produced Panasonic NiMh
cells actually have an equal, if not higher voltage than that of NiCd
cells. The main perk of using a NiMh battery is the higher capacity, up
to 3300 MAH in the Sub-C sized cells.

Resistance

Each cell of a battery has internal resistance, which limits the power
it can put out. A cell with the lower Internal Resistance (IR) will
always be better. Early NiMh cells had a high IR making them not
perform as well as NiCd or recent NiMh cells. Also, the connectors,
wire, and battery bars in a pack all have resistance. Resistance is
what is stopping the flow of electrons. The lower resistance in
everything, the better. The stock connectors on pack are horrible. They
have high resistance, and over time will wear out and get even worse.
Getting some low loss connectors such as Deans Power Plugs will help to
cut down on the resistance. The wire is also a place where you can cut
down on the resistance. You can use some 12 gage wire in place of the
thin wire that some pack have. Also, if you look at regular battery
pack the cells are connected with thik, foil like strips of tin. These
are horrible compared to solid copper, or silver and gold plated
battery bars you can get. Each of these things alone may not seem like
a big deal, but by replacing the connectors, wire, and battery bars you
can reduce the resistance in the circuit.

Batteries, Airsoft and You

Batteries for airsoft have two general characteristics, voltage and
capacity. Capacity is measured in mAh. Voltage is measured in volts.
Amps is a measure of how strong a current is. Capacity is just how much
power the battery can hold; it is basically how long you can use the
battery before it stops being able to power the system. Amps measures
how much power a battery can push out. Voltage is how fast it pushes.

Think of a battery as a water balloon. The mAh measures how much water
is in the balloon. Voltage tells you how big a hole you have in neck of
the balloon. Amps tells you how much pressure is being exerted on the
balloon. Resistance measures how much fabric you have blocking the
water from coming out.

So...more or less mAh is more or less Water. Basically what volume of
water you have to work with. Voltage tells you how much water you can
let out of the balloon at one time. A bigger neck on a balloon will let
more water out at one instant. More or less amps measures how fast the
water is moving out of the balloon. More pressure on the balloon makes
the water come out faster. The Resistance over the neck slows the water
from flowing. The less resistance, the more efficiently the water will
be delivered.

The main things Airsofters are concerned with are how much water they
have and how much they can deliver at one time. mAh and Volts. For
advanced users, the discharge rate (measure in Amperes, varies from 20A
ro 35A -- 30A is ideal)

You should usually aim to get the battery with the highest mAh rating
you can because it will last longer. This is why it is preferable to
use a "large" type battery (generally between 1200mAH and 3000mAH) as
opposed to a "small" type battery (generally 600 mAh). There will be no
adverse side effects to using a battery with a higher capacity; it will
simply last longer before it runs out of juice. A battery with a higher
mAH rating will not damage a gun.

The capacity rating of milliAmp hours means that if you drew the rated
amount of milliamps from the battery, that the battery will last for 1
hour before "dieing". For example, a 3000 mAH battery can deliver 3
amps (1 Amp = 1000 milliamps) for one hour continuously, 6 amps for 30
minutes, or 1.5 amps for 2 hours. A battery's rating is usually "\20H",
meaning that the rating is for 20 hours. For example, a 3000 mAH
battery is specified to deliver 150 mA for 20 hours. The batteries will
have a slightly less capacity in an AEG application (where they will be
providing a high current for a short time) since the higher load is
more stressful for the batteries, but you can still compare mAH ratings
between batteries.

The battery's voltage determines how much power the motor will have.
Stock AEGs take an 8.4 volt battery. Upgraded AEGs sometimes need
higher voltage battery packs, such as 9.6, 10.8, and the insane 12 volt
pack. The higher voltage will make the motor turn faster (higher ROF)
and/or harder (to drive those bigger springs). Please also note that a
higher voltage battery will put much more stress on your motor and the
mechbox internals. You can easily tell what voltage a battery has by
counting the number of cells; each NiCd or NiMH cell is nominally 1.2
volts. A 10 cell pack has 12 volts. A 7 cell pack is a standard 8.4
volt pack. The power of the motor (measured in either watts(W) or
Horsepower(HP), 746 W = 1 HP) is a function of the voltage it is being
fed and the Current it is drawing. Watts equals Current (in Amps, 1000
Milliamps = 1 Amp) times voltage. Please note that the motor will draw
more amps running at a higher voltage since it acts somewhat (not
quite, but good enough for a simple comparison) like a resistor. The
motor follows Ohm's law: Current(in amps) = Voltage divided by
Resistance (in ohms). The resistance of the motor stays somewhat
constant. So, the amount of current the motor draws will increase
linearly with the voltage. Since the power of the motor is volts
multiplied by current (which also increases with the voltage), the
motor's power increases with the square of the voltage, while the
current increases linearly with the voltage increase.