Common Questions About Li-Polys

[Zep]

By: Zep

Coulden't find this info on the site, so i thought id post it in here from another site.. some info i was looking for

Might help some of the new guys asking this question. maybe move into the FAQ section

Cheers.

I don't know about anyone else, but I feel like the only person on this board who uses only li-poly and li-ion batterys. It seems like someone out there some where posting "i dont like li-polys because they destory your internals." or "omg!!11!!!! li-polys destory every gun they touch." Well because Jaws of 1st-Sword is so amazing he posted some common questions people ask about li-polys and I fiqured, I might as well share the information to fellow airsofters I have never seen in real life.

Jawz wrote:
So, to summarize and clear up the myths about LiPos:

• Are LiPos expensive?
  No, not necessarily if you know where to shop -- just like everything else in life! But if you compare batteries with the same capacities, you will find that LiPos are indeed cheaper!
• Are LiPo chargers expensive?
  Even the cheapest LiPo chargers for $10 including shipping are smart chargers! Try to get a new one for your NiCds/NiMH for that price! The fancier you want your charger to be, the deeper you'll have to dig into your wallet -- obviously.
• Are LiPos dangerous?
  If you treat them well, follow common rules for LiPos, and do not short them, no. Admittedly, they have a higher potential to do damage than regular batteries.
• Will LiPos give me an "insane" ROF?
  Not necessarily. This depends on the specifications of your LiPo, your motor, and your spring.
• Are LiPos more complicated to maintain?
  They only require a little bit more care because they are more sensitive to overcharging and overdischarging. Especially the latter could pose a problem for players who neglect the decreasing ROF and are trying to squeeze that last BB out of their LiPo.
• Bottom line: Would you recommend LiPos?
  I personally have not used "conventional" batteries in my AEGs anymore for probably a year and have been into airsoft only since Nov. 2007. After purchasing close to two dozen different LiPos, I have never looked back and do not miss NiMH or NiCds at all. The next "evolutionary" step after using LiPos is to switch to LiFePO4-based batteries! They are much safer and can be recharged at a much higher amperage, but they are too bulky at this time.

Jawz
Jawz wrote:
Well, I have completely switched over to LiPos for a while now and probably have 8 or 10 of them (I stopped counting : ) ranging from 7.4V, 2000mAh to 11.1V, 5000mAh.

Here are a few FAQs that I gathered for myself:

1. Can a 7.4V LiPo compete with an 8.4V or 9.6V NiCd/NiMH battery?
If we are comparing a LiPo and conventional battery of the same size, ie. 7.4V, 2000/2200mAh, 10-15C discharge and an 8.4V/9.6V mini-type, the LiPo will give you a higher ROF (!) if the conventional battery cannot provide enough amperage. This leads to the next question...

2. What's the "C-rating" of a LiPo?
"1C" is the amperage rating of a battery, ie. if a battery says "7.4V, 2000mAh" then 1C corresponds to 2000mA/C. The "C-rating" shows how much continuous amperage a battery can provide. So if you see a "20C" rating on a 2000mAh battery, this means your battery can deliver

20C x 2000mA/C = 40000mA or 40A continuously.

I am stressing the word "continuously" because an AEG can momentarily draw way over 50A, especially on semi. There is a documented case in Denmark with a "Franken-gun" that draws even over 320A!!! LiPos can provide "bursts" for a few seconds, eg. from 25C to 30C without getting destroyed.

3. What does amperage have to do with ROF?
A battery may have enough voltage, but if it cannot provide enough amperage under load, the voltage will drop significantly and your ROF will do down, too. Take this simple real life example: You may be able to get 15V with your 10 AA Duracell alkaline batteries, but I highly doubt that it will pull your M120 spring, simply because the discharge rate is too low!

Many cheap 8.4V and even 9.6V NiCd/NiMH have a lower discharge rate than LiPos and that's why their ROF is lower than with a 7.4V LiPo. But if you use good cells (like those from Elite) that allow a discharge of 30A, you will see that those 9.6V batteries are indeed superior when it comes to ROF. FYI, if you want customized packs, I can recommend these guys:
http://www.cheapbatterypacks.com/tst...asp?sid=896598

They are fast and their work is clean!

4. So if I have a good battery, should I switch over to LiPos?
That depends on what you want to use your gun for and when. Here are few things to consider:
- Pros:

• Trigger response: If you are a sniper and need instant trigger response, an 11.1V LiPo will make your heart beat faster! This is something you have to feel for yourself to enjoy it!
• ROF: With 11.1V, you will empty your mag faster than you can sneeze . Since there are a lot of CQB'er here on this site, I guess that's another incentive for a LiPo.
• Space availability: In crammed spaces such as the handguard of an M4 or G36C, a 7.4V LiPo is heaven-sent. Here's a quick length comparison
  
  
  
  ... and thickness comparison:
  
  
• Extended gaming time: Since energy density of LiPos is much higher than conventional batteries, this is another plus for LiPos. I don't even bother recharging my 11.1V, 5000mAh LiPo during a two day airsoft event even after 8,000+ rounds on my ICS M4.
• Winter games: Have you ever played in freezing temperatures? I have seen 50-75% of guns going down, even those with 3000+ mAh simply because the cold weather will take a toll on battery power. At that time, my puny 2000mAh LiPo was still happily up and running .
• Costs: In comparison to the amount of energy that conventional batteries offer, LiPos are cheaper -- yes, cheaper! You just need to know where to buy them . Recommendations will follow later.

- Cons:

• Initial cost: The initial investment for LiPos is comparable (if not lower) than conventional batteries, but AEGs often include NiCds or NiMHs already and that's why you usually don't care about buying additional batteries. Things look different, though, if you buy a "high-end gun" that normally does not come with a battery. Since you have to get a battery anyway, this would be a good time to switch to LiPos.
• LiPo charger: A LiPo needs a dedicated charger! DO NOT RECHARGE LIPOS WITH REGULAR CHARGERS, or it will blow up your home! No further comments needed because YouTube has a bunch of videos that tell all the story!
• "Explosive:" LiPos store an incredible amount of energy and therefore, a certain standard of care is needed. As long as you don't abuse it, ie. no hacking, drilling, overbending, twisting, burning, or whatever comes to your mind, it will be your best AEG companion. Otherwise, I again refer to the YouTube videos.

Bottom line: If you're happy with your current battery and it is still serving you well, stick with what you have. If you want more performance, LiPos are the way to go (until we find another energy source, like nuclear energy *LOL*).

5. Charging LiPos
LiPos come with two wires: the main beefy wire and the smaller wire with a balance tab:



You can see in the above picture that the top LiPo has three wires whereas the bottom one has four! That's because the wires are used to monitor the individual cells. A 7.4V LiPo has two cells (2 x 3.7V = 7.4V), and each cell gets one wire that will be connected to the black (ground) wire for monitoring. An 11.1V LiPo has three cells (3 x 3.7V = 11.1V), so three wires are needed for each cell plus one grounded wire, which result in four wires total.

The reason why a balance tab is needed is because of the voltage sensitivity of LiPo cells. If you let the cell drain below 2.9V, it's pretty much unrecoverably dead no matter how hard you try to recharge it. If you go over 4.2V, you better have a good home insurance because it may blow up on you! That is the reason why you cannot use regular chargers!!!

There's another small issue that one needs to be aware of: Sometimes, the configuration of the balance tab is different, ie. the polarity is switched! That is the case with Tenergy LiPos! I don't know what would happen if you plugged such a balance tab into a recharger because I caught this little detail early enough when I gathered information about LiPos. It was not a big deal to gently pull out the wires and put them back into the correct order, but still something to keep in mind. Interestingly, Tenergy offers a LiPo charger (for good money, of course) that has polarity protection :.

Attention! Please stay away from this kind of LiPos that were also offered on eBay:



There is no balance tab here, and that invites you to use a regular charger!!!

6. How much are the LiPos and chargers, and where do I get them?
This is my favorite part! LiPos are relatively cheap depending on what capacity and voltage you prefer. My main source for LiPos is eBay from sellers in Hong Kong! Now before you frown your forehead, let me tell you that I had dozens of transaction from Hong Kong, and I have always been pleased with the products. Sure, waiting time can kill you if patience is not one of your virtues, but generally, items arrive within 10-16 days.

As a reference, 7.4V Lipos with 2000mAh (10-15C) can be purchased for around 25 bucks. BTW, I always include shipping when I talk about costs.

The higher the discharge rate and the higher the amperage, the more expensive it gets (d'oh!). I coincidentally bought my 11.1V, 5000mAh (12C, ie 60A discharge!) and 7.4V, 5000mAh (12C) LiPos for around $60 from a US-based etailer. Look around if you can get a similar price from conventional batteries!

A very good sub-20 dollar charger is the following from AirSplat.com:
http://www.airsplat.com/Items/AC-BC-ELE-LiPo.htm

*Edit: Unfortunately, AirSplat does NOT offer the above charger anymore!*

It can recharge 2 and 3 cells, ie. 7.4V and 11.1V LiPos and has three LEDs that indicate, which cell it is charging. Red LEDs turn to yellow when the charge is complete. My only small concern is that it gets quite hot after several hours of recharging my beefy LiPos.

Otherwise, other cheap Chinese LiPo chargers from "eSky" or so do the trick, too. Just keep in mind that they often do not come with an AC/DC adapter, but alligator clamps that you hook up to your car battery. I still bought some of them and used AC/DC adapters instead that I had left over from my broken ethernet switches. Works fine!



Jawz wrote:

7. Can I use LiPos with my guns?
When I first started using LiPos, I was very, very cautious because of its immense power. But of course, you live and learn, and I got bolder.

Now I have come to the conclusion, that with some essential modifications, running an 11.1V LiPo is quite predictable and a lot of fun. Just because guns are made in China, it doesn't mean they cannot take that kind of power. My KWA G36C for example is advertised as LiPo-ready, but got its sector gear stripped after only 4000 rounds, whereas my stock Cyma AK-74 (CM031) is still running strong after 6000 rounds! *Edit: Make it 9,000 now!*

These are the few things that I personally think have to be modified to make a gun LiPo-ready:
[*]Piston:
This is the main weak point in a gun -- even when it is a brand name gun! I don't know how many pistons I have wasted (and they are expensive!) before I settled on the one piston that worked incredibly reliably not only in my guns, but also in other people's guns that I know: The G&P Polyacetal piston!



They are similarly priced like other polycarb brethren, but last "forever." This doesn't mean they don't break; they are just much tougher!

[*]Bushings:
Higher speeds will create more friction and heat, especially around the shafts. Just as a precaution, I recommend metal bushings, or if the gearbox has at least 7mm bushings, use ball bearing bushings.

Like I said, this is only a precaution, and I have inspected stock nylon bushings that showed no significant signs of wear after several thousand rounds with an 11.1V LiPo.

[*]Spring:
If possible, stay with a spring that is not stronger than an M110. If you have upgraded your gun with a tightbore barrel, ball bearing metal spring guide, ball bearing piston head, and you have great air seal, your gun will shoot very closely to 400 FPS, which is a common field limit. It seems that using an M120 spring will exponentially increase your rate of failure.

Unfortunately, they are some springs that do not retain their tension very well. That's why I (from my experience) recommend the
- Guarder SP110 (which acts very much like some other M120 springs);
- Madbull M110 (unfortunately, the lacquer on those springs rubs off and create a mess inside the gearbox)
- Matrix M110 (a shorter spring with a smaller diameter that does not bind with pistons with smaller diameter such as the DeepFire).

Please stay away from PDI: I tried three PDI 170% springs that initially gave me 390 FPS, but eventually ended up with merely 360ish after 3 months!


Alright, I guess that's it for now! I hope this helps!

[Sportco]

Jawz wrote:

into airsoft only since Nov. 2007. After purchasing close to two dozen different LiPos
"24 batteries in 4 years... wow... this guy MUST be an expert (expert WHAT) and i've been using the same Nicad 1100 for 2 years now... plus the same Nimh 2000 for about 1.5 years...

There must be something wrong with ME..

Are LiPos expensive?
No, not necessarily if you know where to shop -- just like everything else in life! But if you compare batteries with the same capacities, you will find that LiPos are indeed cheaper!

You'll notice he didnt tell you where to shop... strange... i'll do the foot work and get back to you on actual prices on LiFePO4... we have an old saying... no pictures... it never happend

From what I know so far: life span(cycles) better then lipo and safety(no fire) and charge time (really fast... good for airplane/car guys who drain there Bats in like 15 to 20 minutes) heavier then lipo

Cheers

[Whiskey]

I just picked up a new pack today , I have been using them for two years and could never go back to Nimh or Nicd.

[Zep]

I was looking for info on this and found it finally, some good info to read. I have 2 now way better for sure.

[ThunderCactus]

Good post, it's always good to see more people posting pro-LiPo, and pro-LiPo safety

But Tyson beat you to the punch a while back lol
It's pretty well everything you went through here with a little more elaboration and over 3 pages
http://www.airsoftcanada.com/showthread.php?t=99899



And just to add on here, Back in the day, the intellect 4200mah battery was top of the line, next to the ELITE 4500mah. I bought my 8.4v 4200mah NiMH intellect battery for about $70, an ELITE would have cost me $90
And for my M4, I switched to an AN/PEQ-15 and custom 9.6v 1500mah packs at about $40 a pop
2yrs down the line, I upgraded to LiPo.
M4 - 9$ for a 7.4v 1600mah battery, with room left over for a triggermaster SW-COMP in the AN/PEQ-15
M249 - $37 for an 11.1v 4900mah LiPo, fills the battery compartment right up
And those are BRAND NAME LiPos!

[audi_bhoy]

I recently acquired a Li-Po battery and charger (7.4v) and if I understand correctly, I must set the discharge to 2.9V per cell, and when charging I must set it to 4.1V per cell. I don't want to blow things up so I'm wondering

[ThunderCactus]

discharge 3.0v per cell, charge to 4.2v per cell, thats minimum and maximum
But you should never have to discharge a LiPo
Just charge & balance

[audi_bhoy]

Alright then! Thanks for the info!

[Sgt. Cooper]

M4 - 9$ for a 7.4v 1600mah battery, with room left over for a triggermaster SW-COMP in the AN/PEQ-15
M249 - $37 for an 11.1v 4900mah LiPo, fills the battery compartment right up
And those are BRAND NAME LiPos![/QUOTE]

Id like to know where you found you lipos so cheap and the charger as well!!! :P

[ThunderCactus]

www.hobbyking.com
The only trouble, is finding a LiPo of the exact dimensions you need, but the site and shipping is just fantastic.
If your buying airsoft specific LiPos (like king arms), your usually getting cheap LiPo's at 3 times the normal cost.

[THe_Silencer]

I find the trigger response too good on a lipo to ever switch back! I personally always run my lipos with a MOSFET of some kind because I'm really OCD about trigger arcing. I don't think trigger contact arcing was mentioned in the post but lipos will wear your trigger contacts out faster than conventional batteries (esp. 11.1v). I think that installing a MoSFET is one of THE most important and essential lipo ready upgrades, and I don't consider an AEG truly lipo ready until it has one.

[Whiskey]

Originally Posted by THe_Silencer

I find the trigger response too good on a lipo to ever switch back! I personally always run my lipos with a MOSFET of some kind because I'm really OCD about trigger arcing. I don't think trigger contact arcing was mentioned in the post but lipos will wear your trigger contacts out faster than conventional batteries (esp. 11.1v). I think that installing a MoSFET is one of THE most important and essential lipo ready upgrades, and I don't consider an AEG truly lipo ready until it has one.

Sorry trigger arcing really doesn't come into severe effect until higher voltage is applied, example : fully charged 11.1v lipo (12.6-12.8v) would cause severe arcing which in turn would create pitting on the trigger contact points and also on you're motors commutator/brushes. Arcing has almost nothing to do with load and everything to do with voltage. The main intent of a lipo battery is to be able to supply much higher load capabilities in a smaller package. Oh and as far as being "lipo ready" you do not need a mosfet for lower voltage Lipo's, hence why my standard non mosfet'd trigger contacts that see a 60c 7.4v 2200 Mah lipo will be in better shape than trigger contacts that see some 9.6v nimh(.....mah) battery . A 12v Nihm/nicd battery will do the same damage to trigger contacts as a 11.1v lipo battery would. Now in no way am I saying mosfets are not a good option , as they are (Just not always required). The archaic contact switch system that has been standard in AEG's for so long has many shortcomings, that can be improved by using a mosfet switch and delegating the trigger contacts to the duty of a relay, to improve electrical efficiency....Now only if we could get a brushless motor system in place for AEG's (non PTW platform) , we would be set.

[ThunderCactus]

Yeah brushless motors would be nice, I keep burning mine out lol
If your going lipo though, it's usually to save space, or attain higher efficiency. And if your doing that then there's no reason not to get the MOSFET switch since it makes the biggest difference when your talking about battery efficiency

[Whiskey]

Originally Posted by ThunderCactus

Yeah brushless motors would be nice, I keep burning mine out lol
If your going lipo though, it's usually to save space, or attain higher efficiency. And if your doing that then there's no reason not to get the MOSFET switch since it makes the biggest difference when your talking about battery efficiency

+1 .

[THe_Silencer]

Originally Posted by BLACKWATER204

Sorry trigger arcing really doesn't come into severe effect until higher voltage is applied...

I really don't get your point here.... I did specifically mentioned the use of 11.1v batteries in my post. Regardless, arcing is noticeable on 9.6v batteries and will even happen on 8.4v batteries. Whether or not you choose to install a MOSFET to prolong the life of your contacts, improve trigger response/ROF, etc. is up to you.