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Bite The Bullet

Size Does Matter - Batteries (2000-03-12)

Size does matter when it comes to AEG batteries.  And why not?  It's only intuitive to even the most casual and non-engineering aligned observer to speculate that the bigger the battery, the more juice it will have.  Additionally, the bigger the battery, the longer it will last and the less you'll have to change batteries in the middle of a heated skirmish!

Overlooked by most first-time airsoft enthusiasts, battery size should be a major consideration when you are shopping for your AEG.  If you're likely to keep your AEG stock, then the consideration is not as large.  "Why?" you ask.  Well here's the low-down.

There are two things you use to measure a battery:
(1) It's voltage (7.2v, 8.4v, 9.6, 10v, and 12v)
(2) It's current (ranging anywhere from 600milliamps (mah) to 3300 milliamps or more Typically you can tell the voltage of a battery just by looking at the number of cells it has.  In the photo above, you'll see a large 2000mah battery comprised of 8 individual cells (in 2 rows of 4).  8 celled batteries are 9.6v and 7 celled batteries are typically 8.4v.  There's also the smaller type 7 cell battery (the yellow one in the photo) which are small type 8.4v batteries.  No rules govern custom batteries (eg. the red M4A1 custom 12v battery) but these are typically labeled accordingly.
Having defined these measurement criteria, here is what you need to know.  The higher the voltage and current, the higher speed the motor will be able to generate in driving a high powered, upgraded spring, thereby translating into higher FPS (feet per second of the BB).  Higher current also typically drives the motor faster thereby increasing rate of fire.  So going back to the first statement of why you should consider the battery size of an AEG before you buy one?  Simply that if you plan to upgrade your AEG to a higher spring rate, you should consider buying an AEG that can take a larger battery that's capable of generating the voltage you need.
To give an example, let's look at the MP5A5.  While a terrific all-round performer, it is designed to accomodate a SMALL 600mah 8.4v battery to drive it's EG700 motor and M90 spring.  This is great if you intend to keep the gun stock but once you upgrade the A5 to an M120 or above, the SMALL  battery simply cannot produce enough power to drive the stiffer spring and the owner is often forced to carry a LARGE 1300mah battery in a strap-on canvas battery bag to drive the upgraded spring (the A5's front grip is only just large enough to hold the SMALL battery).  The situation is even more severe in the MP5K and PDW series AEGs which utilize the even smaller 7.2v stick type battery.

So what?

Well most airsofters simply resent having to carry an external battery since it ruins the authenticity of the gun.  Heck if you didn't mind the external battery bag, you could carry as large a battery as you need.  The classic example is the Vulcan where I've seen some folks carry car batteries on their backs to drive these monsters!  For some who have been forced down this route with the more compact AEGs but can't stand the sight of the external battery bag, many methods have been derived to hide the large battery, such as by storing it in a gutted magazine, gutted scope, and other black metallic boxes attached to the gun.  These custom solutions often require the owner to buy individual power cells and soldering them together in a fashion that fits the intended storage compartment (whether it be in the scope or the mag, or any other contraption).

The table below shows voltage requirements for typical spring upgrades.

AEG Spring Minimum required battery to drive the upgrade
M100 Small 8.4v 600mah battery (barely)
M120 Large 8.4v 1300mah battery, preferably 1700mah battery
M130 Large 8.4v 1700mah battery
M140 Large 8.4v 1700mah battery
M150 Large 8.4v 2000mah

The table above only represents the typically needed battery sizes.  For some guns like the M4A1 and AUG, custom sized batteries are available to drive the higher spring rates.  These custom batteries typically have a short life span with higher voltages, but benefit from their ability to fit inside the stock storage compartment of the AEG.  For example, the custom 12v 600mah battery for the M4A1 can power the M150 upgrade and fits snugly in the front foregrip.  Lifespan is limited to 600 rounds or so.  Larger batteries obviously last much much longer.

As you can probably derive from this information - if you're planning to upgrade your weapon, it's best to get an AEG that has room to store a large battery.  That's why AEGs like the AK47, M16A1/A2, G3A3/SG1, and MP5A4/SD5 make such great upgrade candidates.  Their fixed stock offer generous amounts of space for a large battery.  In the case of the SG1, you can even deepen the stock (via a small modification) to fit a EXTRA LARGE 9.6v battery for super power!  One thing you should also be aware of is that ANY spring upgrade will require an EG700 motor or above.  The EG560 simply does not have enough power to drive stiff springs.

If you're thinking to yourself that "Hey, I don't need to upgrade anyways", here's another thought.  You can increase the ROF of a stock AEG simply by moving to a battery with higher amperage ratings. On a stock AK47, the difference in using a LARGE 8.4v 1700mah battery and a LARGE 8.4v 2000mah battery is quite apparent; the 2000mah battery drives the BB's out at a much higher rate (can you say "Bullet Hose"?)!

Alright, so does this mean that you should go out and get a 9.6v 3000mah battery with M150 spring and EG1000 motor?

Absolutely not!  Overdoing it will strip your gears and wear down your AEG unnecessarily.  Due to the design of AEGs, you cannot run the motor too fast, and driving an EG1000 with a 9.6v 3000mah (or even an 8.4v) battery would translate into instantly stripped gears before you can even get your first 10 shots off!  However if you've installed an upgraded spring, the extra resistance on the motor will allow you to go up one notch on the battery scale and still be relatively safe.  Sound confusing?  It is and there really isn't a set guideline as to what works and what doesn't - that's the beauty of it all - you should trial and error to see what combination fits your needs the best.

Here's a table based on our own experience to guide you on what's reasonably safe:

  EG560 * EG700 EG1000
M90 (stock) 9.6v 2300mah (max) 8.4v 2300mah (max) 8.4v 2000mah (max)
M100 - 9.6v 2000mah (max)
8.4v 2000mah (recommended)
8.4v 2000mah (max)
M120 - 9.6v 2000mah (max)
8.4v 2300mah (recommended)
8.4v 2300mah (max)
M130 - 9.6v 2300mah (max)
8.4v 2300mah (recommended)
8.4v 2300mah (max)
M140 - 9.6v 3000mah (max)
8.4v 3000mah (recommended)
8.4v 2300mah (max)
M150 - 9.6v 3000mah (max)
8.4v 3000mah (recommended)
8.4v 3000mah (max)
12v 600mah (recommended for M4A1)

Disclaimer: The maximum recommended battery ratings are based on experience at RedWolf airsoft.  Actual maximum's may vary depending on the "mileage" of the AEG being modified and the gearbox type in question.  The reader should be aware that ANY upgrade will increase wear-and-tear on AEGs and you should not expect an upgraded AEG to be as durable or even last as long as a stock AEG under sustained use.
Notice that the entire column for EG560 is "-" for anything above a stock spring.  As I mentioned above, ANY spring upgrade would invalidate the EG560.

Also note that we typically don't encourage use of 9.6v batteries.  The reason is that the power is driven up quite a bit and unless you have a very highly rated spring - otherwise the 9.6v battery may provide too much power and leave you with stripped gears - it's like revving an engine too high for too long a time beyond redline.  LARGE 9.6v batteries also tend to cause carbonization at the motor brush contacts and may require more meticulous maintenance to keep things running smoothly in the long term.

So in summary, here are some basic rules to remember.

1. AEG Upgrades require use of large batteries or custom batteries
2. More voltage and current translates into more torque and higher rate of fire
3. EG1000 motors have more torque by nature than EG700 motors so you may not need to feed an EG1000 with too much voltage and current to achieve maximum performance
4. LARGE 9.6v batteries (ie with amperage of 1700mah or more) tend to wear out motors quicker
5. More is not always good.  There is a limit to what you can match up in terms of motor, battery, and spring.  Too much good stuff will strip your gun!

For a full list of batteries that we carry, check out our accessories section.