How many people have tried a 2S lipo (7.4v) as compared to a 7cell (8.4v). Just curious of how much of a loss in ROF that 1.0v would be. 2S lipo with a good MAH would be a nice compromise in voltage, runtime, and weight, as least IMO. Thanks for the help in advance as always.
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No personal experience but I have heard from others that they do not notice a difference in ROF, something to do with the LiPOs discharge rate or something. Personally I would rather have the Lipo.
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Location: (Overbrook, the most west hood in Philly) Phildadelphia, PA
Posts: 977
Quote:
Originally Posted by sarin99
The higher discharge rate of the 7.4v lipo will give you an ROF between an 8.4v NIMH and a 9.6v NIMH.
That was it glad the random info I pulled out of my ass was correct
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These all prove that your thinking that a 7.4v Lipo cannot put out the ROF of an 8.4v NIMH, is completely wrong. The 7.4v Lipo in the video is only 20C, if the battery was a 25C, it would put out an ROF closer to the 9.6v.
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How much current does a "typical" airsoft motor draw?
If it draws less than the discharge rate of a 9.6v NiMH AND a 7.2v LiPO (let's say that both batteries have a discharge rate that is higher than the motor can draw), are you telling me that the LiPO will fire faster even though it's a lower voltage? So, for example, our motor draws 5A when firing. The NiMH battery's C is higher than 5A, and so is the LiPO's. Why will the 7.2v battery fire faster?
How do you prove these allegations in terms of V=IR or P=VI?
ETA: I don't doubt YOU, I doubt the math people are using to justify these statements.
In the first article, his M249 requires 22 Amps. Most airsoft NiMH packs have a discharge rate of around 12C. So lets say we have a 8.4v 1600mAh 12C NiMH and a 7.4v 2000mAh 25C Lipo. The discharge rate for the NiMH would be 19.2 Amps. This would be underpowered in his M249. The Lipo's discharge rate would be 50 Amps. This would meet the full requirements for the motor. I'm still not sure how the extra Amps would effect the ROF. But the power of the Lipo would be much greater than the NiMH, uing P=VI. But the extra Amps would have to be given off somehow, whether it be heat or spinning the motor faster than it was designed to. Is my thinking on that right?
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I can understand if the rate of fire goes up simply because the motor is starved for power. That's a battery problem, not a physics problem.
My question is what happens if the motor is not starved for power. Does the RoF still go up using a LiPO?
ETA: Please don't read any of this as being "dickish". I don't understand where these numbers and allegations are coming from, and I want to understand.
I'm not, I would like to know as well. In the end it doesn't really have any bearing on me, as I'll stick to my easy to charge NiMH's. I've been thinking, KWA states that the "Lipo Ready" statement only applies to Lipos that are 20C or less. This must mean that the discharge rate has a detrimental effect if it is too high. Which would mean that, in my thinking, the extra amperage is going to the motor, spinning it faster than it was designed to go.
Edit: In my post above this I referred to the discharge rate as the amperage. This is incorrect, but it won't let me edit my post anymore.
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Now I'm wondering if all of our AEGs have been starved for power all along.
I also have to wonder what the design specs are for how fast the mechboxes are supposed to cycle. Can something like a stock Marui last just as long running at 100% of the motor's capacity but at 7.2v?
Now I'm wondering if all of our AEGs have been starved for power all along.
I also have to wonder what the design specs are for how fast the mechboxes are supposed to cycle. Can something like a stock Marui last just as long running at 100% of the motor's capacity but at 7.2v?
Very good questions, I have no idea what the answers may be. One may only pray to the Airsoft gods for answers. That or get a multimeter and a plethora of batteries.
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These all prove that your thinking that a 7.4v Lipo cannot put out the ROF of an 8.4v NIMH, is completely wrong. The 7.4v Lipo in the video is only 20C, if the battery was a 25C, it would put out an ROF closer to the 9.6v.
And here's one that proves the opposite! The quality 9.6v NiMHs (Not the **** echo-1 stock crap) more than outperform the 7.4v LiPo.
I think we need to compare the results between 9.6v from a battery and 9.6v from a heavy duty variable power supply.
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I've got a pair of inductive ammeters at work that I can easily clamp onto one of the battery wires in my KWA. I'll do that this weekend to share some real world results.
I've also got adjustable DC power supplies (voltage and current) that I can play with to see when my KWA blows up. Uhhh, maybe not.
no expert here , and the numbers may be partially factual information but this is more of an example that i was reading from scouring the web:
2C=2000 maH so if you use a 20C lipo it should mean that it can give full power to the device in less time then a nimh because of the output power regardless of the volts---so if the motors max power draw is 5000 mah then with a lipo you will be giving it full power because a 20c puts out 7000 mah, 25c 10000mah --whereas with a 3800mah nimh you will only get a max of 3800 mah
i tried looking up the specs on the generic chaoli motors used in jg/echo1 and many others and there aren't any specs that i can find. also these size motors are used for RC units as well so my guess is that these motors will operate normally between 6-12v and 500-XXXX mah being that they are variable speed/power motors. as long as you are within the range of the motors abilities it will function.
so if the max draw on your motor is 5000mah, you could never achieve it with a nimh battery unless it was greater then 5000 mah no matter what voltage battery you put to it, but if you get a 7.4v 20c lipo your output will be 7000mah so you can fully power your motor.
missed-- to increase ROF you can either increase voltage, mah or both. www.all-battery.com same awesome batteries but at 1/2 or greater cost than aeg sites
(naturally this is without any electrical engineering)
Location: (Overbrook, the most west hood in Philly) Phildadelphia, PA
Posts: 977
Quote:
Originally Posted by shuky
missed-- to increase ROF you can either increase voltage, mah or both. www.all-battery.com same awesome batteries but at 1/2 or greater cost than aeg sites
shuky
If I get what you are saying, a 5000mAh NIMH would increase the ROF more than the same voltage NIMH with a mAh rating of <5000 mAh?
I suppose that makes sense, the ROF increase couldn't be that large though
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no expert here , and the numbers may be partially factual information but this is more of an example that i was reading from scouring the web:
2C=2000 maH so if you use a 20C lipo it should mean that it can give full power to the device in less time then a nimh because of the output power regardless of the volts---so if the motors max power draw is 5000 mah then with a lipo you will be giving it full power because a 20c puts out 7000 mah, 25c 10000mah --whereas with a 3800mah nimh you will only get a max of 3800 mah
i tried looking up the specs on the generic chaoli motors used in jg/echo1 and many others and there aren't any specs that i can find. also these size motors are used for RC units as well so my guess is that these motors will operate normally between 6-12v and 500-XXXX mah being that they are variable speed/power motors. as long as you are within the range of the motors abilities it will function.
so if the max draw on your motor is 5000mah, you could never achieve it with a nimh battery unless it was greater then 5000 mah no matter what voltage battery you put to it, but if you get a 7.4v 20c lipo your output will be 7000mah so you can fully power your motor.
missed-- to increase ROF you can either increase voltage, mah or both. www.all-battery.com same awesome batteries but at 1/2 or greater cost than aeg sites
(naturally this is without any electrical engineering)
i hope this may help a bit.
shuky
Actually, most of what you said is completely false. This is exactly how misleading information gets spread.
2C does NOT equal 2000mAh. The "C" number is a measure of how fast the batteries will discharge, and mAh is a measure of the battery's storage capacity. A 1000 mAh battery will discharge in 1 hour at 1C. At 2C, it's not magically a 2000 mAh battery, it will discharge in half the time.
More mAh will NOT increase your rate of fire if all other things are equal. I will concede that if the higher mAh battery has a higher discharge rate, the ROF may increase because there is more current available to the motor, assuming it hasn't reached equilibrium.
Since darn near your entire post is based on an incorrect assumption, pretty much all of it is incorrect.
Please educate yourself a bit more before you decide to post something and claim it as "fact". It's no crime to admit you didn't know something. In fact, I learned something in this very thread. I learned that my assumptions about motor current draw were incorrect.
I may be picking up a 7.4v LIPO to do some testing, even if the "why" and "how" questions still aren't 100% clear to me, a simple audacity check of ROFs will be pretty clear.
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i apologize if i may have made things a bit confusing, i did not claim to have any facts stated, and i also stated i was not an expert. if you read the first line of my post i state it is an example and some info may be factual; but you explained it better than my non-posting experience posting. i was merely using numbers as an example.
bottom line is: the lipo puts out more mah then a nimh. for experimental purposes only, a 20c 7.2v lipo is comparable to if not better than a 8.4v 5000mah battery. the 20c 7.2v lipo would be putting out 70A while the nimh would be putting out 50A ( provided the motor is capable of bearing the load)
in theory Generalporaboo, yes. the 5000maH should put out about 50A while a 3800 maH should put out about 38A.
ie i have a 9.6 1600 mah battery in my gun, rof is about 1450, i throw on a 9.6 3800mah rof 1750.
regardless, to be able to determine max efficiency, one needs the specs of the motor being used of which i am not able to find any.
THE ABOVE TEXT IS FOR EXAMPLE ONLY AND SOME OF THE INFORMATION STATED MAY NOT BE FACTUAL-- FOR DEMONSTRATIONAL PURPOSES ONLY
i apologize if i may have made things a bit confusing, i did not claim to have any facts stated, and i also stated i was not an expert. if you read the first line of my post i state it is an example and some info may be factual; but you explained it better than my non-posting experience posting. i was merely using numbers as an example.
bottom line is: the lipo puts out more mah then a nimh. for experimental purposes only, a 20c 7.2v lipo is comparable to if not better than a 8.4v 5000mah battery. the 20c 7.2v lipo would be putting out 70A while the nimh would be putting out 50A ( provided the motor is capable of bearing the load)
in theory Generalporaboo, yes. the 5000maH should put out about 50A while a 3800 maH should put out about 38A.
ie i have a 9.6 1600 mah battery in my gun, rof is about 1450, i throw on a 9.6 3800mah rof 1750.
regardless, to be able to determine max efficiency, one needs the specs of the motor being used of which i am not able to find any.
THE ABOVE TEXT IS FOR EXAMPLE ONLY AND SOME OF THE INFORMATION STATED MAY NOT BE FACTUAL-- FOR DEMONSTRATIONAL PURPOSES ONLY
Well yes, except mAH is a measure of battery life (as I understand it.) It means "milli-amp hours", which is the number of milliamps it puts out per hour of continuous use. Batteries don't put out milliamp-hours, they put out milliamps. The mAH rating has absolutely no effect on ROF/other performance, only length of battery life before it must be recharged.
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bottom line is: the lipo puts out more mah then a nimh.
No, it doesn't. It can provide more current due to a higher discharge rate. Discharge rate is not the same as mAh.
Quote:
Originally Posted by shuky
THE ABOVE TEXT IS FOR EXAMPLE ONLY AND SOME OF THE INFORMATION STATED MAY NOT BE FACTUAL-- FOR DEMONSTRATIONAL PURPOSES ONLY
Posting this after posting misinformation and unsupported "facts" doesn't make it OK. Please don't post any more on the subject until you KNOW what you are talking about.
Also, this forum has rules about posting. Please start using your shift key where appropriate, not just to say "I am not an expert" right after offering expert advice.
Quote:
Originally Posted by sarin99
I may be picking up a 7.4v LIPO to do some testing, even if the "why" and "how" questions still aren't 100% clear to me, a simple audacity check of ROFs will be pretty clear.
I was speaking about finding the equilibrium ROF of an AEG motor with one of the EEs I work with. He told me to try wiring several battery packs of the same voltage in parallel. They should supply enough current to overcome the lower discharge rates of the NiMH/NiCD batteries and show the true max current draw of the motor. I guess we just keep adding batteries until it doesn't increase the ROF.
If one of our more astute members could supply me with a cable drawing (with multiple connectors) that would allow me to connect multiple batteries in parallel, I'll get it made and try to mine some actual data.
Bracket and I (mostly Bracket), connected two 9.6v NiMH batteries together in parallel, and there was a noticeable increase in the rate of fire. We aren't sure how much the increase was because the chrono was acting weird, but it might have gone up from 12 RPS to 19 RPS just by adding more current. Please note we did not increase the voltage, just the current available to power the motor.
I will concede that a 7.4v LiPO could possibly have a higher ROF than a NiCD/NiMH 8.4v battery, and I think the difference could be dramatic where a mini battery has to be used.
Just to add my experience to the mix... I've been solely a lipo battery user for the last 2+ years now. I use both 7.4v and 11.1v, depending on my gun setup; they have a discharge rate of at least 25C (consistent, not burst). My experience is that the ROF from my 7.4v lipos is higher than an 8.4v large nimh/nicad pack but slightly lower than a 9.6v large nimh/nicad pack. I have not done any "official" RPS testing though. Lipo batteries, if treated & charged properly, can be a worthwhile alternative when battery space is limited. Plus, if I can get near the results of an 9.6v nimh/nimh batter while only using the voltage of a 7.2v battery , then I consider that another benefit.
NIMH or LIPO
glad the random info I pulled out of my ass was correct
No, it doesn't. It can provide more current due to a higher discharge rate. Discharge rate is not the same as mAh.
