Jump to content


LiPo Battery Warning!!!


  • Please log in to reply
341 replies to this topic

#281 gcw360

gcw360

    Supreme Guru

  • Super Moderator
  • PipPipPipPip
  • 11,596 posts
  • Gender:Male
  • Location:New Jersey
  • Interests:Airsoft (Especially repair and customizing), Fly Fishing, Fossils (Especially Dino), Snakes, Photography
  • Country:

Posted 07 March 2012 - 05:10 PM

View PostWrath, on 07 March 2012 - 04:42 PM, said:


But on page 1 it says to not exceed 18A, aren't they both over spec?
Good catch.  It was also posted in 2008.  The recommendation is 15C, 20-24 amps continuous.

#282 Wrath

Wrath

    Enthusiast

  • Members
  • PipPip
  • 44 posts
  • Gender:Male
  • Country:

Posted 07 March 2012 - 06:06 PM

View Postgcw360, on 07 March 2012 - 05:10 PM, said:

Good catch.  It was also posted in 2008.  The recommendation is 15C, 20-24 amps continuous.

Ah, thanks. I just read the thread in its entirety this morning.

#283 gcw360

gcw360

    Supreme Guru

  • Super Moderator
  • PipPipPipPip
  • 11,596 posts
  • Gender:Male
  • Location:New Jersey
  • Interests:Airsoft (Especially repair and customizing), Fly Fishing, Fossils (Especially Dino), Snakes, Photography
  • Country:

Posted 07 March 2012 - 06:13 PM

I'm impressed and thank you for taking the time to do so.  Most people would simply ask the question rather than doing a bit of research.

#284 niko_gpsy

niko_gpsy

    What's a Warranty?

  • Super Moderator
  • PipPipPipPip
  • 5,880 posts
  • Gender:Male
  • Location:Atlanta, GA
  • Interests:Keeping those damn squirrels from putting their filthy little paws on my peaches in my backyard. Oh, Yes. It's not just a hobby, its a passion!!
  • Country:

Posted 08 March 2012 - 01:44 PM

View PostWrath, on 07 March 2012 - 04:42 PM, said:


But on page 1 it says to not exceed 18A, aren't they both over spec?
I believe that post was from 2008 and the recommended spec has changed a bit.  We now recommend 20A.
Personally I would say 20-24A is just fine.

#285 Dbspinkrox

Dbspinkrox

    Enthusiast

  • Members
  • PipPip
  • 36 posts
  • Country:

Posted 05 June 2012 - 09:35 AM

Has anyone had experience with the new turnigy nano-tech batteries?

#286 niko_gpsy

niko_gpsy

    What's a Warranty?

  • Super Moderator
  • PipPipPipPip
  • 5,880 posts
  • Gender:Male
  • Location:Atlanta, GA
  • Interests:Keeping those damn squirrels from putting their filthy little paws on my peaches in my backyard. Oh, Yes. It's not just a hobby, its a passion!!
  • Country:

Posted 05 June 2012 - 12:02 PM

I use some nano-tech batteries and they seem to hold up well.  But many are out of spec so make sure you buy one as close to 20A as possible.  You can burn out contacts, motors and wiring if you use a battery way out of spec without a Mosfet unit.

#287 Dbspinkrox

Dbspinkrox

    Enthusiast

  • Members
  • PipPip
  • 36 posts
  • Country:

Posted 05 June 2012 - 01:24 PM

View Postniko_gpsy, on 05 June 2012 - 12:02 PM, said:

I use some nano-tech batteries and they seem to hold up well.  But many are out of spec so make sure you buy one as close to 20A as possible.  You can burn out contacts, motors and wiring if you use a battery way out of spec without a Mosfet unit.
Thanks for the fast reply.  Will this batt fit in the sr stocks?
http://eliteairsoftb...ttery-pack.aspx

#288 niko_gpsy

niko_gpsy

    What's a Warranty?

  • Super Moderator
  • PipPipPipPip
  • 5,880 posts
  • Gender:Male
  • Location:Atlanta, GA
  • Interests:Keeping those damn squirrels from putting their filthy little paws on my peaches in my backyard. Oh, Yes. It's not just a hobby, its a passion!!
  • Country:

Posted 05 June 2012 - 01:57 PM

Sorry but I have no experience with that battery.  But if you look in your users manual it states that the butt plate battery dimensions are
4"X1.25"X0.62".  So it may fit but could be a bit tight.  Maybe someone that owns this battery can chime in.

#289 Vosmalus

Vosmalus

    Newbie

  • Members
  • Pip
  • 1 posts
  • Gender:Male
  • Location:North Carolina
  • Interests:Prepping, Hunting, Fishing, Airsoft
  • Country:

Posted 07 June 2012 - 11:57 AM

Hello, I'm new to Airsoft and i just received my KM4 SR10. I also purchased a tenergy micro controlled universal ultra fast-charging w/intelli-ic2 chip the insturctions says to current level 1 for batery packs between 0.8 and 5Ah, current level 2 for 2Ah and 10Ah, current level 3 for 3Ah and 30Ah... now the intellect premium 9.6 Ni-MH butterfly/nunchuck 1600mah doesn't say what "Ah" it is anywhere on it nor does the airsoftmegastore say. Also i have no idea what amp it is.. i know your not supposed to exceed 15a and the website says this battery has a 30amp drain rate, is that the same thing?? All this battery stuff has me scared lol. How can you find the C rating as well? Any help will be much appreciated.

Edited by Vosmalus, 07 June 2012 - 12:12 PM.


#290 spartin878

spartin878

    Newbie

  • Members
  • Pip
  • 22 posts
  • Gender:Male
  • Location:Oak Park California soon to be in Wooster Ohio
  • Country:

Posted 08 June 2012 - 10:36 PM

I know that KWA sells their guns as lipo ready, my only question is should I purchase a mosfet or is the gearbox able to support the lipo with out one?

#291 niko_gpsy

niko_gpsy

    What's a Warranty?

  • Super Moderator
  • PipPipPipPip
  • 5,880 posts
  • Gender:Male
  • Location:Atlanta, GA
  • Interests:Keeping those damn squirrels from putting their filthy little paws on my peaches in my backyard. Oh, Yes. It's not just a hobby, its a passion!!
  • Country:

Posted 09 June 2012 - 08:27 AM

Personally I think a mosfet is a great upgrade but because there are always up and downsides I would read up on such a device before deciding on it.
KWA recommends that lipos stay around 20amps output.  So an example would be a 11.1V 1600mah 12C battery which will give you a 19.2amp output.

#292 spartin878

spartin878

    Newbie

  • Members
  • Pip
  • 22 posts
  • Gender:Male
  • Location:Oak Park California soon to be in Wooster Ohio
  • Country:

Posted 09 June 2012 - 09:30 AM

If im using a 10.8 now would their be a noicable difference in performance if I was using a lipo? Im hesistant on using a lipo for the fear of the increased load on the gears and such.  I know their all reinforced and such but still I dont wanna use one and a few months later hear my piston just strip.

#293 gcw360

gcw360

    Supreme Guru

  • Super Moderator
  • PipPipPipPip
  • 11,596 posts
  • Gender:Male
  • Location:New Jersey
  • Interests:Airsoft (Especially repair and customizing), Fly Fishing, Fossils (Especially Dino), Snakes, Photography
  • Country:

Posted 10 June 2012 - 06:19 AM

View Postspartin878, on 09 June 2012 - 09:30 AM, said:

If im using a 10.8 now would their be a noicable difference in performance if I was using a lipo? Im hesistant on using a lipo for the fear of the increased load on the gears and such.  I know their all reinforced and such but still I dont wanna use one and a few months later hear my piston just strip.
What you gain with a LiPo is a lot of performance in a small, light package.  The volts are maintained better than NiMh batteries and therefore once I went LiPo I never looked back.  And now that the prices are coming down, LiPos are a great option IMO for more people.  I've been using Lipo's exclusively in all my KWAs for years now with no ill effects from them. I can tell you that at LC XI all of the guns on the KWA team that I saw ran with LiPo batteries also and none went down for issues with a gearbox.  Will you see a noticeable change in performance vs a 10.8?  That's had to say.  But I do and given my type of play and the set-up I have, a LiPo is the best and only option.

#294 philsaudio

philsaudio

    Enthusiast

  • Members
  • PipPip
  • 277 posts
  • Gender:Male
  • Location:Atlanta
  • Interests:Playing Bass, Grandkids, camping
  • Country:

Posted 07 July 2012 - 08:22 AM

May I attempt at explaining what is happening with your battery and gun and what could possibly motivate KWA to spec a battery with lower than the "state-of-the-art" of LiPO battery technology current delivery.

Analogicly speaking:

Lets say that electrical power is like water being poured on dirt. The flow of the water causes the power to be consumed. The water can do the work of removing dirt from a sidewalk.

In your gun then the dirt would be your BB's and the water is the power stored in your battery which is being used to cycle the motor and GB to remove the BBs from your gun.  

You can store water it in a container, pour it through a "conduit" such as a straw, a hose or a 4" pipe. You could hold the container up and pour the water on the dirt from above your head, from waist level or sit it on the ground and poke a hole in the bottom of the container. The higher you hold the container the more force the water has to remove dirt.

Now if you held the container at waist level and poured it on the dirt below out of a bucket the force would be mighty as the water hit the dirt and washed it away but the bucket would be empty pretty fast.

If you emptied the bucket by pouring the water into a funnel then into a hose the container would not empty as quickly but the bucket would last longer. Same with pouring it through a straw, eventually the bucket would empty but the force of the water hitting the ground would be much less than the force when the bucket is just poured out onto the ground.

If you were to hold the same bucket over your head and pour it out onto the dirt the force at which the water impacted the ground would be greater than the same amount of water poured from your waist height at the same flow rate.

If you were to pour the water into a funnel then into a straw the flow rate you would get holding the bucket over your head would be more like the flow rate you would get if you held it at your waist. In this case the flow of work is more controlled by the resistance of the straw than the height of the bucket

In the electrical system we have two rates, the rate at which the water can be released from the bucket and the rate at which the load of the motor and connected pneumatics can accept the water.  So the battery connected to the load is like the bucket going into the funnel into a hose (battery C rating) then connecting that hose to a straw (what the motor will draw at any instant). In this case the lower flow rate will become the total flow rate.

To be clear, the lower of the two hose/straws will limit how “fast” water can be poured out of the container. The limiting component can be either the battery or the load  and this changes as the gun is fired and cycles.

In battery terms:

the capacity of the bucket is the  battery milli-amp-hour (mah) rating.
the height of the bucket above the dirt is the battery voltage rating
the size of the first conduit after the funnel is the battery “c” rating.

The last straw is then the internal resistance of the loaded motor, which varies as the motor starts, runs and stops. This is where the system is no longer static DC and behaves like alternating current where the current is not changing direction but magnitude as the gun cycles.


This is a picture of the current profile of a typical AEG. ( http://www.digicon.s...t_amplified.jpg)Posted Image

As you can see it changes from when the trigger is first pulled (at the left and higher than the rest of the waveform) and it changes as the gun cycles from bb to bb and it changes as the gun motor runs and the armature rotates.

The small changes (many many of them) are the current spike caused as each winding of the armature moves through the magnetic field. Motor speed can be extracted from this part of the current waveform.

The five cycles to the right of the first big peak are the GB cycling. Each cycle would be a BB firing if the gun were loaded etc.

The first big peak is the effect of the motor having to overcome the inertia of the unmoving system.

So although the battery can supply so much current (perform into a funnel and hose of a certain size) the system power profile is usually limited by the constantly changing load.

In water terms this means that;
If the first hose straw (battery “c” rating) is larger than the second hose then the second hose controls current flow.
If the second hose/straw is larger than the first now the battery C rating would control or limit the flow of water.

So now that you have a firmer grasp on what is going on, I am hoping the answer the question of, “ why would KWA want you to limit the C rating on your LiPO? ” will make a little more sense.

Gearbox destruction is caused by fast moving parts colliding, and that is happening all the time with the piston slamming the CH many times per second. The faster you make it go (raise ROF) the more energy it takes during the same time period and hence more current is drawn by the load to do more work in a shorter period. More current more heat more work over less time.

To slow things down a little and make the gun outlast the warranty something in the circuit needs to keep the load from drawing as much current as it would like, which causes trigger contacts to burn, piston over-cycling, premature engagement and fuse blowing.

The engineers at KWA were probably ( my own presumption) told by people responsible for warranty costs to limit the liability caused by   the marketing department who make the marketing “LiPO ready” claim and limit their warranty liability. Easy spec a battery that will limit the current available to the gun as to not blow itself up. If this were a car we would call that a “governor”. So in effect limiting the specification of LiPO to 15C they are telling you to buy a battery with a built in governor or void your warranty.  

How much current can a full spec LiPO dump into the load? Since the big draw is only for that first cycle or around 50 thousandths of a second (50mS) we use the peak rating of the LiPO not the continuous rating.

So an 11.1vDC 25C/50C 1600mah battery will deliver up to 80 amps to the motor if the motor so asks. Note the waveform, the beginning of the peak is off the scope. It is 8x the cycling current of the rest of the five shots that follow.  

Why doesn’t this blow the fuse? It is a time sensitive device.
This next diagram shows that picture.
http://extreme-fire....<!--NoParse2-->

The right hand side of the graph shows that a 20A fuse can conduct 22-24 amps up to 100 seconds or indefinitely It can conduct 35 amps for 10 seconds and 90 amps for one second without blowing. It can conduct 150 amps for .1 second or two full cycles of the GB. Surely this is enough time to blow it to pieces. Fuses are not really going to protect you from much more than a short in the wiring.

I hope this helps you understand a little better what is going on and why KWA specs low “C” batteries for their guns if you want them to be in warranty.

PS: Most NiMH batteries are ~10-12C equivalence.

Current and fuse profile pictures are From Airsoft Mechanics forum (http://forums.airsof...1.html#msg35801)

Peace

#295 niko_gpsy

niko_gpsy

    What's a Warranty?

  • Super Moderator
  • PipPipPipPip
  • 5,880 posts
  • Gender:Male
  • Location:Atlanta, GA
  • Interests:Keeping those damn squirrels from putting their filthy little paws on my peaches in my backyard. Oh, Yes. It's not just a hobby, its a passion!!
  • Country:

Posted 07 July 2012 - 09:22 AM

Good info but one thing you failed to mention is that even guns you custom build to be "ANY LIPO READY" the premature failure rate is high. So for a company to recommend an "in-spec-battery" is not absurd.  And it has been my personal experience that what they recommend is one thing but what I would do with their products is another.  I have ran lipos that was capable of up to 80amps without mosfets for a year without problems.  So what would you consider  "LIPO READY"?  Should it be able to handle 100,200, or even 300amps with absolutely no possibility of failure?  Come on Phil, lets live in the real world. :P

#296 philsaudio

philsaudio

    Enthusiast

  • Members
  • PipPip
  • 277 posts
  • Gender:Male
  • Location:Atlanta
  • Interests:Playing Bass, Grandkids, camping
  • Country:

Posted 07 July 2012 - 12:10 PM

This is the real world. Why then would KWA not recommend the majority of LiPO batteries out there but limit it to 15C pretty much the same as a NiMH?.

Cause if they did recommend higher C batteries they would be repairing a lot more guns under warranty.

Real World enough?

I just wish this gun would fix itself for free and I would happily put a 7.4 or 9.6 in it again and be shooting it instead of writing this.

peace

#297 niko_gpsy

niko_gpsy

    What's a Warranty?

  • Super Moderator
  • PipPipPipPip
  • 5,880 posts
  • Gender:Male
  • Location:Atlanta, GA
  • Interests:Keeping those damn squirrels from putting their filthy little paws on my peaches in my backyard. Oh, Yes. It's not just a hobby, its a passion!!
  • Country:

Posted 07 July 2012 - 12:23 PM

Majority of the "lipo ready" guns can't use "majority" of the batteries in the market right out of the box without suffering from accelerated failure.
And a 11.1 15C battery does NOT perform the same as a 9.6V battery. I have a 11.1V 12C battery that kicks my 9.6V NiMH out of the water.
9.6V yielded 18 and 11.1V 12C 1600mah yields 22rps. So I don't know where you are coming from.


#298 philsaudio

philsaudio

    Enthusiast

  • Members
  • PipPip
  • 277 posts
  • Gender:Male
  • Location:Atlanta
  • Interests:Playing Bass, Grandkids, camping
  • Country:

Posted 07 July 2012 - 03:10 PM

View Postniko_gpsy, on 07 July 2012 - 12:23 PM, said:

Majority of the "lipo ready" guns can't use "majority" of the batteries in the market right out of the box without suffering from accelerated failure.
And a 11.1 15C battery does NOT perform the same as a 9.6V battery. I have a 11.1V 12C battery that kicks my 9.6V NiMH out of the water.
9.6V yielded 18 and 11.1V 12C 1600mah yields 22rps. So I don't know where you are coming from.


I mean the C rate of the KWA specified LiPO is similar to the C rate of a typical NiMH. . The voltage is not the same so it will not perform identically.

A fair comparison would be how the 40/80 C battery would work. If the gun itself is limiting the ROF the big same voltage battery would have the same ROF as the 15C battery. If the battery is limiting the ROF then the ROF will go up as the C rating goes up.

If some other vendor says their gun is LiPO ready and it is not;  that is no reason for KWA to use the same standard. All I am trying to point out is that if one actually understands what is going on one may actually know why this battery works differently from that battery, how it works differently, and how it will work differently in one's gun, then maybe one would be able to make a better upgrade or purchase choice; instead of blindly believing a label they do not really understand what the label maker meant by it.

Peace

Edited by philsaudio, 08 July 2012 - 04:52 AM.


#299 UKBananas

UKBananas

    Newbie

  • Members
  • Pip
  • 7 posts
  • Country:

Posted 25 July 2012 - 11:15 AM

I have a KM4 SR10 and as we know there is a recommended max of 1600Mah / 15C (24 amps max)
I'm running 1800Mah / 15c (27 amps max) that I got from the pro shop.
I'm suffering from large voltage drops in the battery during use because it's 15C (low quality batteries).

I'm running everything stock, haven't got into upgrades yet, and don't want to damage anything, which is why I didn't go with a 20C or better battery. I'm aware that a higher C battery is a better battery from my RC experience.

Now if I downgrade the voltage from 11.1v (3 cell) to 7.4v (2 cell) and run a 2000 Mah battery at 30C (better quality battery), this is a maximum 60 amps, which we're told would damage the gun's internals, however if the voltage is lowered to 7.4v - does this mean it's less likely to damage the gun?

On an RC Heli I'm used to a BEC controlling power to the motor, so generally you just get the best battery you can afford (highest C rating) and don't have these problems or rely on the C rating to stop too much power going to the motor (what we're doing with the 15C cap), there should be an equivalent for Airsoft so we could get nice high spec batteries.

Thanks for your help!

#300 niko_gpsy

niko_gpsy

    What's a Warranty?

  • Super Moderator
  • PipPipPipPip
  • 5,880 posts
  • Gender:Male
  • Location:Atlanta, GA
  • Interests:Keeping those damn squirrels from putting their filthy little paws on my peaches in my backyard. Oh, Yes. It's not just a hobby, its a passion!!
  • Country:

Posted 25 July 2012 - 11:44 AM

A type of BEC control would be a nice option to have in an AEG and there are fets that you can install. I have just installed a raptor fet in my sr5 and it does everything but fetch the paper in the morning. lol




1 user(s) are reading this topic

0 members, 1 guests, 0 anonymous users