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Is 7.4v 20c/3000mah reciver battery enough for Airsoft?
I just ordered a lipo rated for 20c discharge (40 burst) and 3000mah, 7.4v
Someone told me that reciver batteries are no good for airsoft as they dont put out enough power. But if my math is right this battery will put out 60 amps. Is there anything I am missing here? |
alot of formally trained GunDocs can agree with me on this i hope, in that if it has a 20C output, doesnt neccesarily mean that your gun will pull all 20C from the battery, it just means the maximum output of the battery is 20C, alot of things will count toward your rate of fire, gearbox shimming and motor height, motor speed, airseal, connector type, etc. if you figure out what your guns demands are and test a few batteries out, you might get a better idea of what works.
PS. I'm no gundoc, please feel free to correct me as needed, this is just wat i think. |
Well, except if the company is known to lie on their battery specs, any 20c 3000mah is equivalent to another, no matter the brand. "Someone" was either misinformed or thought you ordered a weaker (Less C or mah) battery pack.
This pack should be enough for anything but a high torque high speed build. EDIT : As sammy said, a lot of factor can affect the amount you can draw, but a 20C battery stays the same from brand to brand unless, as I said, they lie on the label. |
You might benefit from posting a link to the battery info/source...
Also...PM Dynamo...he'll know. (tell him that I refered you) |
Here is the battery. seemed legit to me. It is the perfect size and has the most MAH I could find (I am running a SAW, not intersted in crazy ROF just want MAH)
http://www.hobbyking.com/hobbyking/s...ver_Pack_.html I will be getting it soon, maybe I can review it. |
You should be good to go with that (as long as you switch the terminals nicely).
Just the general words of advice ...don't use mini tamiya (or even large...best to go with Deans or better) ...careful when switching connectors...don't short out the pack ...always charge with the balancing tap ...with a new battery in your setup...until you get to know how it's working, check it periodically to see how it's holding up and discharging. |
+1 /\
Also on hobbyking, if you hang around on the page for a while, they'll offer you the item for a dollar less :D, just noticed that!!!! |
Thanks!
This will be my first lipo. I always convert to deans and have a good guy that will do it for me. I have a balance tap charger already picked out.... |
Echo all above.
Also, that brand is good shit. The output should more than suit your needs. |
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Everytime I get redirected to the http://www.hobbyking.com/ra.asp?z , then 404 not found. |
Even if that battery looks fine, it's a bit underpowered.
It is about equivalent to a small 1500mAh buffertube pack. Yes, it will work, but probably not for SAW purpose. The pack is a 2s2p. That means that it's actually two packs (4 cells). And since it's rated 20C constant, it means that theses cells each are rated 10C. That is not much for a sustained fire pack. This pack is a lot more suitable http://www.hobbyking.com/hobbyking/s...ipo_Pack_.html |
Excellent catch on the 2s2p! My mistake!!
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So does that mean this double pack is only going to give me 30amps as opposed to 60? 10c x 1500mah for each pack x2 packs? This still should be doable as most 9.6 nmh only run about 22 amps...
Sadly those bigger packs are too big for my gun, this was the only one over 2200mah that would fit... |
While searching for a good NON 2s2p I found this:
http://www.hobbyking.com/hobbyking/s...dProduct=23134 Anyone can explain to me what is that battery? Even being 2s2p, it's still two times 32.5c at 2100mah... seems overkill for that small package? Or, something normal that could fit, based on the original pack : http://www.hobbyking.com/hobbyking/s...dProduct=20390 Just get two if you feel you lack the amperage needed for the day. |
FYI if you can add a mosfet to your SAW it will make your battery efficiency ridiculously good
I'm getting around 400mah/box mag on my 249 with lipo/mosfet/triple torque gears at 1400rpm and 380fps |
FYI if you can add a mosfet to your SAW it will make your battery efficiency ridiculously good
I'm getting around 400mah/box mag on my 249 with lipo/mosfet/triple torque gears at 1400rpm and 380fps |
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But because that is driven by two smaller packs, they are more prone to failure. It's kinda hard to explain (especially since I just work-up), but two packs never equal a single larger pack. That is the reason they mark it as receiver pack. It's good for 5-10 amps at most, what ever the C rating says. What are the dimensions of the space you have for your battery? |
One big bag of milk = big long non-stop drink
Half a dozen little milk cartons = empties quickly and you need to stop drinking to have more ready to go *see...battery stuff is simple.... |
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They shipped today.... Not sure how that's even possible.. If these were even 2 10c packs with 1500mah each that's still 15 amps each. which should = 30 amps no? That reciever pack would basically barely fit. (they are going into the nutsack of a stoner lmg). If this does not work I am basically out 40 bucks and stuck having to buy some 2200mah lipos. |
Well...
.20g bbs they sell at Canadian Tire are still .20g and 6mm... yet they are crap. The same applies to batteries. There is no magic at work. If the 2200mAh is the same voltage and same size as the 3300mAh, there is something else that is different. Theses are marked and marketed as receiver packs. Even though their theorical rating is 30C, they are not. Theses packs will work fine, but they will bloat very quickly and you will have to replace them soon. The size of the wires on the pack is a give away... if the wires can't handle more than 10A, how do you want to get more than that to your gun? |
Well Fudge! :rocket:
... |
I really like the Team great hobbies lipos
35 and 50 C continous rates (NOt burst) under 40$ charge at 9 amps (reccomended) I love em :) http://www.greathobbies.com/producti...d=TGHL32002C35 the advantage to the pack you chose is as mentioned, its 2x2cell. in theory you have 2 7.4s, if they have 2 seperate connectors that is. so you can still use them till they die. |
um. Everybody is caught up on the mah and c rating. Take another look at the battery guys.. Look at the leads. They're ~22gauge wire, typical for a receiver battery. Yes the CELLS are rated to drop some serious current, but the WIRES are woefully under sized for this sort of application. Depending on the gun it's used in, those leads could pose a serious problem.
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wow I didnt see that, the power leads are very small.
As mentioned they might burn up under heavy load. |
You'd also get next to no current out of them lol
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Yeah, now, if, and I stress, IF you know what you're doing, you can go out and grab yourself some quality 16ga or better wire and solder that directly to the cells. Then re-heatshrink the battery because you'd have to cut it all up to get to it. It can be done, I've done it before, but there's high potential to burn your house down if you don't know what you're doing.
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I had thought about that, I think Id almost be willing to try LOL
Looks like I'll be hitting the hobby store for some 16 or 14 G Silicone noodle wire LOL I wonder if Blackjack wont mind Clear shrink wrap (picked some Clear 3 inch for rewrapping Large batteries that had the wrapping tore up). And to answer a previous statement -- The Stoner Will have a Simple mosfet unit - I Just have the assemble said mosfet :) |
My best advice is make sure to tin the new wires very well (apply flux to them before tinning), and be very careful applying the new heatshrink. My first time doing it I ended up puffing the battery slightly from the heat I applied. Slow and steady is the way. Thinner heatshrink is also better because it takes less heat to activate.
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ya the heating of the wrap is the only think truley bugging me :)
lipos hate both hot and cold so you cant precool the battery in the fridge before putting on the wrap and the other side, using semi direct heat to melt the wrap on a battery that doesnt respond well to hot LOL although i have heard that RC folks tend to store them in the freezer |
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Parallel = current doubles. Serial = voltage doubles. The "C" rating is a direct measure of the maximum current a pack can give. In this case, the combined two packs are 20C, each pack will only give half of that maximum current. Otherwise they would mark the pack 40C since it would be better for marketing purpose. But it's not safe to run the pack at 40C... |
Just to make sure i dont burn my house down..
the pack in question has 2 red and 2 black. the question is each "pack" is 2 x 3.7v lipos thus 4x 3.7 the packs are currently wired as 2x 7.4 (with 1 red and 1 black each) when i wire it for use I'll want to basically combie the 2 red together and the 2 blacks together which should give 7.4 @ 3000 correct? if i wire them with 1 pack red to the other Black the outcome would be 14.8 @ 1500 now taht said it all depends on how the balancer is wired. a 7.4 has 3 wires but a 14 has 5. My charger uses the balancer to read the voltages and charges through the main power connector. so I wonder if the balancer connector is going to be the crutch |
NO.
Just use the leads marked as "DISCHARGE" And charge through the balance port. The packs are internally wired, you cannot decide what cells you want to use (except through the balance plug, but that is sub 1A usually) |
Ive never understood how a lipo charges through the balancer,
forinstance, the TGH batteries state a 3 to 5 C charge rate. on a 3000 mah battery its a 9amp charge. how do the tiny little balancer wires hand 9amp of charging power? also please define the No. no i dont want to combine the 2 red and the 2 black wires (obviously in pairs not ALL together LOL) no the balancer wont be a problem? |
Yes, combine both of the leads. I don't think Kos-Mos is looking at the battery very hard. This is a reciever battery, which has TWO SETS of discharge leads. Typical thing to see on a reciever pack. Yes, both sets of discharge leads are soldered to the same place and yes by replacing the wiring, you are effectively combining them.
Here's a quick sketch of how the battery is wired inside. There's no way to wire it to get 14.8v unless you desoldered all the cells and stacked them in series. http://img.photobucket.com/albums/v2...psef00b3df.jpg Quote:
Ugh. Let me try to take you through the math. Each cell is 1500mah. There are four cells. Take two cells and put them in parallel and you have 1s2p. Put that group of cells in series with a second group and you have 2s2p. With me so far? Hope so. Now, if one cell has 1500mah and a 20C discharge rate, 1.5 amps x 20 = 30 amps. So each cell can pass current at 30 amps. Now let's put that beside another cell (ie in parallel). Now you have two cells that can each drop 30 amps. What's 30 + 30? 60? Correct. The two cells together can drop 60 amps. Now let's look at the battery as a whole, it's 3000mah 20c what's 3 amps x 20? 60? The same? holy fuck I think we're on to something! I think you understand the general idea but the part you keep forgetting is that each cell is NOT 3000 mah, it's 1500mah. The two cells TOGETHER add up to 3000. That's WHY you make a pack like this. If each cell were 3000mah 10c as you seem to think, then they would be advertising the battery as 6000mah, not 3000. Understand now? |
Its like $10 for a new, proper lipo. Just buy the correct battery before you set something on fire lol
And for shits, since its a 2s2p, would you have to charge it as a 4s battery? |
Well first off I asked in this thread if this was a good battery, was told it was and ordered 2 of them. Second these are the ones that fit my gun. Third, hobby king still instists the pack is fine for my gun.
Scooter when I get the batteries in I will turn them over to you for a rewire, depending on cost. |
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This might help some people too.. http://www.rchelicopterfun.com/rc-lipo-batteries.html |
So as I understand it, you're balancing 2 parallel cells as one cell.
Then isn't it possible for those cells to be unbalanced between eachother? I'm not understanding how it distinguishes between those 2 cells on the one balancing port Like on parallel pack chargers, it uses a common main charging line for all the packs, but keeps all the cells separate. So 4 2s packs would be treated as an 8s battery. But a parallel pack puts 2 cells on one port, so it charges a 4s like a 2s? Unless there's some other science at work that seems incredibly dangerous... |
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However, that pack is still not suited for anything over 10A. Read the reviews and forums about them. The Turnigy Nanotech are great!, however not when in 2p setups. They not only use smaller cells, but cheaper apparently (similar to their B-Grade series). I have bought a LOT of LiPos from Hobbyking, around 50-60 as of now. The packs that are parallel wired are known to be over-rated. I had two bloat on me (receiver packs that is), and one explode. Their "main" batteries are really good though. Won't last 200-300 cycles, but they are cheap and deliver while they are fresh. That is the packs that use Xs1p setups. Most receiver pack I bought have a diode and short circuit protection on the "Discharge" leads, to prevent failure in case of a faulty servo. If it is the case with theses packs, it means that connecting both leads will trigger the circuit and might just blow the pack. Unless you remove the shrink to make the changes, I would advise against jumping both leads. |
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