Airsoft is a world full of old technology and an industry of slow moving innovation. Look at the batteries we use. Up until recenlty, most AEG’s came with nothing more than a NiCad battery, and most only with an 8.4v. The discharge rate of the cells were poor, and you had to deal with poor quality Tamiya connectors, as well as thin and low quality wiring. It’s time to update the technology we use.
Let us address some myths regarding lipos:
- Lipos WILL explode and are very dangerous to use
- Lipos are too powerful for anything but a heavily upgraded airsoft gun.
- Lipos require a lot of babying
Okay, so the first one isn’t really a myth, but hearing the horror stories some people tell, you’d think that lipos are prone to failure and then spawn gremlins who then tear up your garden, embroider your underwear, wet your bed, then swap your sports car with a Prius. Yes, lipos CAN (not will) explode if you push them out of spec. The same can be said about NiCad and NiMH batteries too! Granted, the later two don’t often fireball, they can spit out all kinds of nasties that will burn you and possibly catch fire in addition to spewing shrapnel upon failure. Keep your lipo within specs (easy to do), and you’ll nary have a problem!
Number two has to be one of the most annoying things I hear about lipos. Everyone is afraid of the big bad lipo battery! Why do people think that a lipo will blow up your AEG? I just don’t get it. Let’s learn some math and understand why this is total nonsense!
First we must understand a thing called discharge rate. This is the rate at which current flows out of the battery. Manufacturers refer to this as the “C” rate of the battery. So if your battery specs say that you have an 11.1v 2200mAh 25C battery, then you know the discharge rate is 25C. Now what does that mean? Well, let’s convert that to something we can understand. To convert the “C” rate to amps (a measure of current), we just use this formula:
C Rate x Capacity (in amp hours) = Discharge Rate in Amps
So let’s look back at the battery we were just talking about. Using the formula we have 25C x 2.2Ah = 55A. Now hold up a minute and don’t freak out when you see that 55A rating. We’ll get to that in just a second. What you need to know is that 55amps is what that battery is CAPABLE of producing. Now let’s switch gears and see what that NiMH battery you have is capable of producing. Most NiMH cells used in Airsoft can discharge with a C rate of up to 12C. Hum…. see where I’m going don’t you? Keep reading. So let’s look at an average mini battery that might come with an AEG; say a 8.4v 1400mAh NiMH battery. Using the formula above we find that it is capable of discharging 16.8amps continuously. Wow, big difference.
Okay, enough of the math, what does that mean to you and your AEG? Every AEG needs a certain amount of current to run. This can vary from setup to setup due to different requirements of the motor and the load it has to drive as determined by the spring strength and gear ratios. Let us look at my M249 for an example. Drivetrain-wise, here are the specs:
- Guarder High Speed Motor
- Madbull M120 Spring
- Standard Ratio Gears
- 8mm Bearings
Now this gun requires about 22A to drive it, and since it’s a PARA version, it only houses a mini battery. WAIT! Didn’t we just find out that the mini battery in the above example only can put out up to 16.8 amps!?!?!? That’s under powering the gun by about 23.6%! So what can we do to increase the performance given the tiny space we have to fit a battery? Well, we can put the battery someplace else and use a larger battery, but that might not be an option. Then we can increase the voltage from 8.4v to 9.6v. Well in this case, there is room to add the extra cell. Adding more voltage will increase the ROF and provide more power to the system but you might not have room for the extra cell either; there must be a better way. Enter Lithium-Polymer batteries; stage right. Lipo batteries are able to fit higher capacities and higher discharge rates into smaller packages than a traditional NiMH or NiCad battery. So let us revisit our space and current conundrum.
We need 22 amps of current to drive our system (AEG’s drivetrain) at 100%. So let us use a 7.4v 2200mAh 25C lipo battery. That has a discharge rate of 55A. Of course, the gun only needs 22A…. and as such WILL ONLY DRAW 22A. The gun can’t and will not use more current than it needs. It will however, try to pull as much as it needs. So when you’re putting that mini battery we talked about earlier in there, we’re over taxing the motor and the battery as the motor tries to draw the full 22A out of something that can’t supply it. With the lipo, we have only used 40% of it’s capability; thus not overtaxing any part of the system! Did you also notice we’re only using 7.4v to drive the system? Nice huh?
So let’s get back to myth number two that says we have to have a heavily upgraded gun to run a lipo. If you were to run a stock gun at 100%, and the stock internals are capable of handling the gun running at 100%, then using a lipo is no problem. Where you run into problems is systems that arn’t matched. You might have a heavy spring with a motor that can’t provide enough torque. Or maybe you have a low quality piston or gears in a high fps rig. Then you’re system isn’t matched (strength of the drivetrain to the load being driven), and regardless of what type of battery your run (3300mAh NiMH or a 2200mAh Lipo 25C), you’re just as likely to trash the piston or gears. DON’T BLAME THE LIPO!
We’ll get to myth 3 soon enough, but I want to give you a moment to chew on all of this information. Let’s see what we’ve learned.
First, as long as lipos are kept within the manufacturers specifications, they’ll run reliably for a long time. Just like NiMH or NiCad’s they’ll present you with a potential fireball of a hazard if you push them outside of the manufacturer specs.
Second, it’s not the lipo that can kill your gun, it’s unmatched components being driving at 100%. If the motor is running at 100%, but the gears are operating at 140% of their ability because of poor quality, then they’ll break. Same is true of the piston and anything else in the gearbox. With that line of thought, a 7.4v lipo is no more likely to break your gun than a large 9.6v NiMH or NiCad!
Well, chew on that for a while and we’ll get to myth three in the next part when we discuss maintaining, charging, storage and precautions for your lipo battery.