LiPo, or Lithium-ion polymer batteries to give them their full name have taken the radio control modelling world by storm and secondarily, have found their way into Airsoft AEG weapons in the last couple of years.
Their inherent ability for large discharge currents and a high number of charge/discharge cycles before their design performance starts to degrade, has made them very popular with Airsofters. They certainly seem to last longer and give a cleaner trigger response than the older battery technologies used.
I use 7.4V 25C 1450mAH capacity stick batteries in my Airsoft weaponry and not only are they small, but one will last me all day, which is a great benefit as it saves me having to worry about charging at lunchtime when skirmishing.
However, the chemistry of LiPo means that there are some associated risks in using them.
Overcharging, crushing, puncturing or short-circuiting this type of battery can cause a fire. Manufacturers insist that you use a correctly designed, balanced LiPo charger (you should never use a NiMH battery charger for LiPo) and you should never leave a charging battery unattended. It has been stated by suppliers that LiPo batteries should be kept in a partially charged state (NOTE: not on-charge) and I therefore periodically charge my batteries up when they are in storage, to avoid them becoming too discharged through the natural self-discharge that can occur between games. I never, ever, leave my LiPo connected to the charger once they have charged up and always disconnect them and switch the charger off at the mains.
There are also quite a few movies on You Tube which show people deliberately puncturing or shorting LiPo batteries to show the effects that ensue. Have a look at what happens - typically they all hiss, smoulder and smoke a lot. Some even spew flames. It's not hard to see how they could cause a fire.
In an attempt to provide a degree of protection, many battery suppliers also sell fire safes or fire bags.
I charge and store my batteries in the fire bag that you see in the photograph above. The bag is made of a fire retardant material and is sealed by a Velcro strip to limit the Oxygen supply in the event of battery combustion.
Again there are movies on You Tube that show some makes of fire bag burning, so it seems that not all the bags for sale out there are up to much !!!
To my mind, if you follow all the safety rules and use a specially designed, quality fire bag laid out on a fireproof surface such as a concrete floor away from anything else, you have taken precautions. Logically, if a battery is damaged, it will smoke and although these bags cannot be expected to contain that, hopefully they will control the flames to some extent and reduce the risk of nearby items catching fire. What is not clear and I leave you to make up your own mind is how to evaluate the effectiveness of the different products out there. Which are the quality ones ?
There doesn't seem to be a lot of proper fire bag product reviews on the Internet with any sort of scientific testing ??
Having seen what happens to a LiPo when its deliberately punctured for "edutainment" on You Tube and bearing in mind how some batteries are squeezed into tight spaces in Airsoft rifles, it occurs to me that one specific risk is that the outer casing of a LiPo battery could become physically damaged after a lot of use. Examining my own LiPo batteries, the outer plastic wrap is slightly imprinted where internal parts of the stock have pressed against the battery inside the gun. I now inspect the battery very carefully for any sign of physical wear when I take it out of the rifle after a game.
Finally, I have to say that I'm not a LiPo battery expert, so don't hold me responsible. This post is just an attempt to get Airsofters to consider the risk of using LiPo batteries without taking adequate precautions.
DO make your own study of the subject and make up your mind.
Tango Mike
