Battery Guide (LiPos, C Ratings, Safety, etc.)

[X]

This thread was originally about how KWA uses C ratings to determine which batteries are safe to use and how that makes no sense at all. I've changed the first post around so that it's more of a center for battery information since this has become a sticky. So if you see some replies that seem out of context, sorry.

General Battery Info:
A = Amp = Ampere. This is a measure of electrical current.

Ah = Amp hour. This is a measure of stored electrical energy. How many amps a battery can deliver for one hour. More Ah = More shots before your battery dies. Some people mistakenly believe more Ah will increase the guns cycle rate (Rounds per second). I will explain later how Ah can indirectly affect your RPS, but in general if you want to shoot faster you either need to increase voltage (V) or modify the gearbox (better shimming, high speed motor, etc).

mAh = milli-Amp hour. Simply multiply Ah times 1000 and you have mAh. This is the number that you commonly see on batteries.

C Rating:

The C rating is this...

1C = the ability to fully discharge in 1/1 hour (60 mins).
2C = the ability to fully discharge in 1/2 hour (30 mins).
15C = the ability to fully discharge in 1/15 hour (4 mins).

This is sort of a combined measurement of the battery's capacity and output in terms of A. So if you have a 1000mAH battery, let's say it can provide 1 Amp for 1 Hour which would be 1C.

One more example. 15C, 2000 mAh battery?
2000mAh / 1000 = 2Ah
2Ah * 15C = 30A
The battery can supply 30 Amps of current.

So what does this all mean to you? The main thing you need to be concerned about is the maximum amperage the battery can supply. For most stock guns 20 Amps is usually plenty. Anything more than this and you are going to be wasting your money. However, if you are trying to pull an M150 spring expect the gun to draw more current. Supplying the gun with more current than it requires will not give any benefit. To little current and you are putting extra stress on your battery and you will see a lower cycle rate. So if you have to choose over or under always choose over. The only downside is a slight increase in the cost of the battery.

NiMH Batteries:

If you are buying a NiMH battery the C rating probably won't be listed. You can assume that it's around 10C-12C unless specified otherwise. There is not much variance in NiMH batteries like there is with LiPo batteries. Since the C rating on NiMH batteries is somewhat constant you can see how some people would believe increasing mAh would net a boost in RPS. This is only true if your current battery is so small that its Amp rating is below the requirements of the gun. In this case moving to a larger battery will increase your RPS because the battery is no longer the weak link in the system.

If you are the type of guy that doesn't take really good care of your gear or are generally destructive NiMH batteries would be a good choice. They can take a lot more abuse than a LiPo battery and they are not as finicky as LiPos about how they are charged. You can use "dumb" slow chargers, butI highly recommend getting a smart charger. "Smart" chargers can charge your batteries about 10X faster than the slow chargers.

LiPo Batteries:


The following link mentions balancers. You should know that most modern chargers now have the ability to balance the cells built in to the charger so it's no longer necessary to get a separate balancer.

LiPo Guide Part 2 (we've already covered the material in part 1) (posted by Gimpalong):
infectedairsoft.wordpress.com/tech-info/lithium-polymer-batteries-part-2/

Disposal information (posted by Ctres):
thunderpowerrc.com/PDF/DISPOSAL-OF-LIPO-BATTERIES.pdf


Below is the old post for reference:

For example:

KWA says do not use a battery rated higher than 15C.

Supposedly from what I've found most NiMH batteries are 10C. So if that's true my battery (3300 mAH capacity) can discharge at a rate of 33A.

So now moving over to your standard LiPo. 1700mAH and 20C. This pack can provide 34A.

Somehow my battery pack is OK because it's higher capacity? It seems to me that Max Amperes and Voltage should be the measurements used to determine the actual output of a battery for Airsoft. Am I wrong here?

My understanding is that Voltage is the primary driver for maximum rotation speed or Rate of Fire in airsoft's case. Maximum Ampere mainly influences the amount of torque a motor is able to provide. Obviously some motors based on design have better torque (large brushes?) or better rpm (small brushes?), but I'm leaving that part out.

So I think that in theory there should be a maximum voltage like in this case 10.8V or 11.1V and a maximum Ampere rating such as 20A or 30A.

[Ike]

You are absolutely correct. The C rating is only good for calculating the amps that a battery puts out. Saying that a battery is stronger than another because it has a higher C rating would be false unless the voltage and capacity of the two are the same. I think I tried to explain this on MIA awhile back and nobody really seemed interested in hearing it. +1 for logical thinking.

KWA's 15c standard is completely without reason. If you're using a shitty Firefox lipo, we'll say 1000mah, that'd be 15 amps. Now let's say you use a large battery with quality cells rated for 2500mah at 15c. That's over 35 amps. Now granted, KWA's motor probably isn't drawing that many since it has quite a bit of torque. But if a 15c battery providing 37.5 amps is acceptable, then what's wrong with a 20c Firefox (which probably wouldn't even hold up to that number if you measured it because they use shitty cells) that is putting out 20 amps? [/rant]

You're on the right track about motors. The motor will only draw so many amps no matter what. As you start drawing amps from a battery, it will lose it's ability to discharge the maximum number of amps. This is why you want a battery that provides more amps than your gun is drawing.

Torque and speed are determined by magnet strength and how many winds there are per armature. The more winds per armature, the more torque (less speed). The fewer winds per armature, the more speed (less torque). It should also be noted that a higher torque motor will also draw less current than a high speed motor. This is why I always use high torque motors when they are available. Even the highest torque motors available (Terminus X and JG blue) are still capable of pushing over 30rps on any spring rate, so there's really very little reason not to use them.

That was a ton of typing on my phone, I don't know what I'd do without Swype.

[Gimpalong]

Infected did a great LiPo guide for those of us who aren't as well versed in amperage, volts, c-ratings, etc, etc. Check it out here:

infectedairsoft.wordpress.com/tech-info/lithium-polymer-batteries-part-1/

[snafu]

Great info here. +1

Sent from my Droid using ProBoards

[Dahm]

Jan 27, 2012 12:13:25 GMT -5 Gimpalong said:

Infected did a great LiPo guide for those of us who aren't as well versed in amperage, volts, c-ratings, etc, etc. Check it out here:

infectedairsoft.wordpress.com/tech-info/lithium-polymer-batteries-part-1/

That is a very good link. Someone should start a post with just that link so we can sticky it.

[koolor]

I say stay away from infected mosfets they are very low quality even if they where 5$ would not buy /rant. Kwa says dont run 15c or higher because lipos under 15c usually have a weak enough discharge they dont harm trigger contacts which is why they advertise "Lipo ready" which is complete bull and nothing but marketing. The best lipos I have ever ran and run (present) are turnigy nano-techs I have taken one down to 200 out of 2200 mah and it still had 7.5v!

[X]

This thread is over three months old, infected airsofts mosfets have nothing to do with this thread and your thoughts on C ratings are just wrong.

Run along now...

Sent from my DROID RAZR using ProBoards

[ATS]

I am still loooking for a link to Part Two "Care and Feeding of your LiPo" - I tihink charging, storage etc will be covered.. anyone have that link!? GREAT INFO!!!

[ctres]

infectedairsoft.wordpress.com/tech-info/lithium-polymer-batteries-part-1/

That should help. Some of the specific products mentioned may be a bit out of date, but that should tell you almost everything you need to know. I personally have the thunder ac6 charger from hobbypartz and it's been great.

[ATS]

Thank you! This has been enlightening and I had heard a lot of the falacies, even from hobby shop LiPo dealers, so learning this is good for business, and I can be more accurate in what I say!

Mad props!