Airsoft Batteries FAQ By: Brad B.Batteries are a grey area for many of the players that are in Airsoft today. Many players have no idea, or have the wrong idea on what they are and what the information that they say they are. To help you as a player this article will address the issue in two parts, the first being the basics. What is it that you need to know to buy a battery, and what the terms are for that purchase? The second is a technical set of information that will help address the specifics of the uber-nerd that wants to have a GREAT battery, instead of just a good one. And yes, there is a difference.
As for the basics, there are two main things that you are going to have to deal with. One is the capacity of the cells; the other is the voltage of the battery pack. Yes, there are a lot of other things to take into consideration if you’re an uber-nerd and want to have the PERFECT battery pack. But, most don’t care beyond the basics, so here we go.
The plain and simple response is this:- Capacity goes directly to the length of time you can pull the trigger and have the motor spin.
- Voltage goes directly to the speed at which the motor spins.
Now, again, this is very basic for right now. So, if you want to talk on the technical side of things, which is later. Just follow the information and hold your tongue for now.
There are some assumptions that are needed to be said here. And address a few comments that have been said regarding batteries and their characteristics will be answered in this text. And will be updated to cover other items as time permits.
- Capacity (mah) - is the milliamp hours that the battery has, this is the direct number that is the overall capacity of the cells in the pack. When you read 3000 mah (which should be mAh, and is not actually pronounced ‘ma’) it means the battery cells are capable of delivering 3 Amps for 1 hour. This is again not the only consideration for the pack, but it is the capacity.
- Voltage - is the ‘level’ of energy delivered. The higher the voltage the larger the electromotive force that the system can exert on the motor windings. So, while that may have lost some of you, it translates to the larger the voltage the harder it will push to spin the motor.
Now, here is where you need to understand some of the system that is involved…I would love to make an easy to follow analogy for you all to follow and this is as close as I can to following the water analogy from the discussion that spawned this write-up.
To understand this, you will have to understand that a water balloon that is dropped on your head from 5 feet will hurt less than one dropped from 50 feet. If you can follow that, then this will follow better.
Capacity of the battery pack is just that, the size of the tank of water. If that is 3000 gallons, or 1500 gallons it is just the capacity.
The voltage is better thought of as the height of the spout on the side of the water tank. It can be from 7.2m from the ground through to as high as 12m from the ground. If you have had basic physics you will understand that the longer that gravity has to effect an object the more ‘power’ it can gain (limited to the critical velocity). So, the same cup of water from 7 meters will be less powerful than the same cup from 12 meters.
Now, you can see that there is a missing component from this discussion that was in the original. That is the size of the pipe.
The equation of the size of the pipe to the capacity is wrong. That is the Drain Rate, NOT the capacity. You can have two battery packs that are outwardly the same: 8.4v 3000mAh, and have two COMPLETELY different responses of the packs in a gun. And the only difference is the DRAIN RATE.
The drain rate can vary wildly, and it is important to know what it is. Some battery packs have smaller drain rates and some are much, MUCH higher. Taking some of the cells that are available commonly to the battery packs we use one can see rates from as low as 15 amps to as high as 50 amps. That would mean that if your system (gearbox, spring, gears, and all) need 25 amps to run ‘normal’ and you have the smaller drain rate of 15 or even 20 amps, your motor will be starved for power.
Which leads me to take on the comment of the capacity making any difference in the ROF of the gun is false as well. The only caveat to that is if the original battery was running the motor in starvation. If the larger pack was a higher drain pack, the gun would be experiencing a higher ROF, but not due to the capacity, but due to the higher drain rates.
So to answer it in a short write-up and this is short…
When you buy a battery pack, here are the things to remember:
- The higher mAh will give you a longer shooting time.
- The higher voltage will give you a higher ROF.
- Be aware of the Drain Rate of the batteries, the higher the rate the higher the cost. (you’re looking for 30-35+ amps)
There are limits to these that SHOULD NOT BE EXCEEDED!
Never attach a higher voltage than a 9.6 v battery unless the mfg specifies it. YES, some will take the voltage of a 12 volt battery pack, some will shoot for a 100 rounds, some will just eat themselves and you will have to replace the whole gearbox and the internals to repair the damage when it fails. If that is what you want, then go for it.
The highest mAh will have no damage to the motor, as the motor will only use what the motor needs. Yes, this is a unique thing to motors, as the magnetic flux inside the rotors will only allow a known amount of current to pass until it self regulates and limits current due to the flux lines collapsing and building inside of it. It is however possible to get a short in the windings, that is normally due to excessive heat, and that will very much look like the motor ate itself from the current. But, it is the short and not the motor that caused the overload. And for those of you that will be more than happy to say that a motor can eat itself with hyper levels of current, I will say yes, but in this system without any EXTREME changes in the system, it is not possible. If you pumped 1000A at 2v through one of these motors, yes it will melt in a very short time.
It has come to attention that many people are unaware about charging times for batteries. Rather than a new post for every noob, I thought I'd just clear it up.NiCadIf you have a Nickel Cadium battery you need to use the following equation:
Battery capacity x 1.4 / Charger Output
For example:
For a 600mah small battery on a 250mah charger: 600 x 1.4 / 250 = 3.36 hours
For a 2400mah large battery on a variable charger charging at 120: 2400 x 1.4 / 120 = 28 hours
NIMHNickel Metal Hydride batteries are less charging efficient and use the following equation:
Battery capacity x 1.5 / Charger Output
For example:
For a 1050mah small battery on a 250mah charger: 1050 x 1.5 / 250 = 6.3 hours
For a 3300mah large battery on a variable charger charging at 120: 3300 x 1.5 / 120 = 41.25 hours
Ni-Cad or NiCad (Nickel Cadium)A single cell is 1.2volts, so if 7 2400mah cells are made into a pack the result is 7 x 1.2 = 8.4 volts. This would be a large battery. Large batteries just mean they usually fit into full stock guns, e.g. M16 or MP5A4. Although some full stock guns can fit a 9.6 volt battery which would consist of 8 cells, or even 10.8volt batteries, which consist of 9 cells. Small batteries have the same layout as large batteries but on a smaller scale. The most you can get out a small NiCad cell is 600mah, where as the most you can get out of a large NiCad cell is 2400mah. NiCad's have a constant level of power and then very suddenly drop off and die. This means your gun has a constant rate of fire right up until the end. NiCad's have to be discharged fully after use to stop the formation of crystals, these crystals shorten the life of your battery. This is also know as when a battery develops a memory.
NiMH (Nickel metal hydride)Nickel metal hydride cells typically have more capacity than NiCad's however this comes at a price. The most you can get out of a large NiMH cell is 3600mah, although these are very rare and 3300 is more common, the most you'll get out of a small NiMH cell is 1050. As I said more capacity does not mean a better battery, this penalty is that, unlike NiCad's, NiMH's slowly lose power until they finally die. This means after a while your guns rate of fire will slowly start to decrease until it becomes hopelessly slow. NiMH do not need to be discharged although it can still be done, for the user to know how long he needs to charge from. However, I’ve heard discharging a NiHM too much can cause damage to the battery. TM Dischargers do not totally discharge batteries for safety reasons.
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