Lithium Polymer (LiPo) Battery Q&A

So since Dino was asking about them I will share what little know how I have about the LiPo batteries.

I have been using these in my high end R/C Helicopters for around 2 years now and still have the same batteries now that I bought when the birds were new. I have 7.4 and 11.1V packs for the 300-400 size birds and I use 3.7V packs for my micros (I have a small fleet of helos). It is funny that airsofters, who are normally apt to jump on new tech, are practically terrified of these battery packs because of stupid youtube videos of them blowing up. Let me clarify a couple of things.

Safety - LiPo batteries have a likelyhood of blowing up the same as your NiMH batteries do. Anyone that has seen a NiMH cell blast small pieces of tin/lead/acid all over a room can attest that they are not quite as safe as you would be lead to think. A LiPo battery can be destroyed in several ways, but mostly through using a non-smart charger to charge the batteries. The videos of those batteries blowing up were done by removing ALL the safety features of the batteries and feeding them direct high amperage power. The one battery I have that lost one cell to a bad controller got warped out of shape even with a completely failed and shorted board. No explosion, no bang. It merely distorted and stopped working. I removed the one cell from the pack and swapped a new cell in its place and was back to flying with it in no time. Since the safety features are actually built into the good batteries, you don't have to worry about any external electronics getting wet or shorting out your safety stuff.

Time - LiPo batteries do NOT quick charge. You can charge a decent LiPo batt at around 1A per cell. The good batteries have a special plug that allow you to charge each cell seperately. It also allows each cell to discharge seperately, thus keeping a dying cell from draining the other cells in the pack. Simply put, having one cell in a NiMH pack that only pushes 3C of power will make ALL cells push 3C. A LiPo with one dead cell will push the other cells at full C just minus that cells contribution. This is a HUGE advantage while flying a couple thousand dollar helo a hundred feet in the air as it only diminishes your performance, not crashing your bird.

Heat - LiPo batteries are made for CONSTANT DRAIN. Anyone ever fired an AEG for a couple minutes straight? Like a SAW or RPK for instance? Ever felt the battery after that time? It was probably so hot that it was about to start melting the heat shrink. NiMH batteries are usually not that high of drain, so when you tax them for long periods at high C drain they get hot. Heat will also cut your performance rapidly with a NiMH and NiCd. The LiPo's that I currently have (at 2 years old) are pushing around 12-14C drain for a good 10 minutes in the helos and they are mildly warm when I swap them out. I am sure putting them in enclosed spaces would get them warmer, but I doubt it would be nearly as bad as a NiMH.

Price - They are not quite as expensive as most people believe. I get the good ones for my helo at around $50 a pop for a 11.1V 1500-1800mAh 18C 3 cell. Considering that a 7.4V could easily operate an airsoft replica that isn't super modified you can run a lot less money per Amp. On a very positive note, they are about a third the size of a comperable NiMH. You can daisy chain several together in the space of a standard 8.4 and triple your mAh.

Now this is all going off of what I have experienced over the last two years. I bought good batteries and a good charger for my helicopter because I really hate having to rebiuld them (my top bird has a head unit that cost more than my last SAW replica). With main rotor RPM's of 3k and a tail RPM of over 15k, batteries are a serious affair for them. A problem with a battery at 100 feet means having to pretty much rebuild your entire bird (as soon as you pick up all the pieces). There are advantages to the LiPo system, but time is not one of them. They take a while to recharge, and they do NOT like being shorted out. You also can kill a battery if you don't keep at least a tiny bit of charge in it all the time. On a positive note, my flightlogger has shown that in 2 years of using the same 5 batteries for my 450 size bird that I have only lost 30 seconds of flight time since they were new (and that includes 3 months of sitting in storage while moving to the new house). That alone has kept me from having to buy more batteries and costing myself over the long run. I have since converted every RC item I have to LiPo and even one of my airsoft replicas has been set to use LiPo too.

That is just a quick briefing on them. Some things may not be fully accurate since this is all off the top of my head right now, but it can at least give a decent idea that most of the rumors out there are all crap for teh most part. People fear what they don't know, and they don't know crap about these batteries. I am sorry, but if the RC community trusts them in their multithousand dollar toys, I am surprised that the airsoft community hasnt done the same. I'll see if I can dig up some of the articles on rcuniverse.com about them that actually base their determination on scientific method instead of like ASR and Arnies with "LiPO's suck.... my friends-neighbors-pastors-cousins-exwifes-kid used one and it blew up in his FACE!!!!!"
Written By Captain

Captain, I'll also add in a few extra things just so people know some other things about LiPo batts.
Alright, if you get a LiPo for your airsoft gun, it is very improtant to make sure that your LiPo has a built in low voltage indicator so it will automatically cut itself off when the voltage starts getting too low. If it doesn't have that built in, then you need to buy a low voltage indicator and connect it to the battery. The reason this is important is because if the voltage in a LiPo drops too low, the battery is basically muffed. IMHO, a good brand of LiPo is ThunderPower and they aren't too bad in price. You can get a good ThunderPower 11.1v 3C 2600 Mah battery for $84.99. Now, ThunderPower packs are a well trusted brand of battery packs. The guys at my local field use them in their $1200+ Align T-Rex 450 SE helicopters running BL motors. Also, keep in mind that you will need a special charger that is designed for charging LiPo batteries as well as a ballancer for charging.

Once you go LiPo, you don't go back... or atleast that's how I felt about it when it came to RC... even though I still haven't bought one for my RC helicopter. Hell, I haven't even repaired it yet... the last crash (due to mechanical failure) killed it and I just haven't really cared much to go buy a new feathering spindle, blade grips, flybar, rotor hub, hoops, tail rotor, etc. Those parts broke thanks to hitting the ground with the rotor head spinning at full throttle and itthen flopping aroung on the ground before I could fill the throttle. However, this crash was still due to mechanical failure.
Written By T.Payne Airsoft

You may want to go with something less than 11.1V though, I used them in one of my replicas to test with (and the battery was a little low at the time) and it sounded like a M11A1 at around 1200RPM. It is amazing how much current (Amps) they can put out. It blows away the other types for that.

They are pretty good on prices for their LiPo stuff. I buy batteries from them for other projects and that is where I got my first batteries from for the helos. It is about time for me to get a new bird, so I will be getting some larger batteries to go with the MH-6 model I will be getting. I did find some good articles on RC Universe that have LOT of technical data on them about the batteries versus standard NiCad and NiMH. Very scientific and a lot of it is over my head as far as drain rates and temperature curves. It is hard to beat them for size to power ratios though, which is why they work great for RC flight stuff. The more pwoer per ounce you can get, the longer you can fly. Which is probably one of the main reasons airsoft never picked up on it. Weight is not quite as critical of an issue when you are dragging a SAW around.
Written by Captain

have a stock Echo 1 M4, with a massive battery box...I want to switch to a smaller PEQ-15 and I hear that only LiPo batteries can fit into this thing

If I were to get a 7.4 V LiPo, would it be too much for my gearbox to handle (stripped piston maybe)? Also, since the charge cannot drop below a certain voltage per cell, does that mean I must periodically charge the battery to prevent irreversible damage? My final question is do these batteries come with the same plug as the standard plug on AEG's, or are most batteries equipped with "dean's plugs"?
Written By Jpresley

No, the 7.4 is equivalent to the 8.4v. I run it in my M60. You can watch the videos in my review to get an idea of the rate of fire.
Written By Animal Mother

The second, smaller plug on the LiPo is the balance lead for balancing each cell's voltage. LiPo's are normally one cell, two cell, or three cell.

One cell = 3.7v (no balance lead)
two cell = 7.4v
three cell = 11.1v

You need a cell balancer along with the charger because both cells need an equal charge/voltage to function properly. If you do not have a balancer, then you risk allowing one cell to drop below 3.7v and if it does, then the charger will not pick up that cell and will think you only have a 3.7v hooked up to it, so in other words, that battery is fried. Also, the primary way LiPos blow is when they have a shortage, the cells get punctured, or they are over charged. If it makes you feel safer, then get what is called a LiPo Sack, which is designed for you to put the battery in, so if it does blow up, the sack will contain the fire without burning the house down.
Written By T.Payne Airsoft