Battery flight times - 80% rule?
10-16-2008, 10:22 PM
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Battery flight times - 80% rule?
Hey guys, just flew the 450 sev2 for the first time. It has a Scorpion -6 motor with a 10T pinion - this is how I bought it. Flew it for about 6-7 minutes then brought it down, as I know that the scorpion sucks a bunch of power. I am using the Flight Power EVO25 2500mah battery. Can someone explain the "80% rule" to me? I'm charging it as we speak, but it looks like about 1640mah is being put back in. Are you supposed to take out 20% and put 80% back in, or take out 80% and put 20% back in? Can you also explain how to calculate headspeed? It is a simple equation, but I simply can't remember it. Thanks guys.
EDIT: Another thing: what's the maximum headspeed you would run 335mm pro woodies at? At which charge do you leave a lipo overnight? Charged? Uncharged? In the middle? Thanks.
EDIT: Another thing: what's the maximum headspeed you would run 335mm pro woodies at? At which charge do you leave a lipo overnight? Charged? Uncharged? In the middle? Thanks.
10-16-2008, 10:49 PM
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RE: Battery flight times - 80% rule?
You're supposed to take no more than 80% out of the pack for better battery longevity - leaving 20%. You would put back in 80% when you charge the pack, or 2000mAh in your case.
The theoretical headspeed = (Motor kV * Battery voltage (under load) * Pinion size) / Main gear size. This is strictly theory and the actual headspeed will be a bit lower. So, if you're using 3S lipos, headspeed = (4400kV * 10.5v (approx.) * 10) / 150 = 3080.
The theoretical headspeed = (Motor kV * Battery voltage (under load) * Pinion size) / Main gear size. This is strictly theory and the actual headspeed will be a bit lower. So, if you're using 3S lipos, headspeed = (4400kV * 10.5v (approx.) * 10) / 150 = 3080.
10-16-2008, 11:29 PM
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RE: Battery flight times - 80% rule?
ORIGINAL: tomtomzz
EDIT: Another thing: what's the maximum headspeed you would run 335mm pro woodies at?
EDIT: Another thing: what's the maximum headspeed you would run 335mm pro woodies at?
Yours should be the same. There only 10 longer than my blades.
Tom
10-17-2008, 02:34 PM
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RE: Battery flight times - 80% rule?
if I'm using the 450 se V2 with the stock 3700Kv motor, 2200mAh outrage with a 12t pinion then theoretically my head speed would be more than 3108. Now is this at 100% power?? because I'm using the align pro woodies and I'm afraid to rip them apart[&o] is this setup ok or should I change pinion/blades/throttle curves??
Thanks a bunch.
about the flight times, with my setup I'm flying 7-8 min putting back about 1700-1800mAh back into my 2200mAh pack. If you're running a 2500mAh pack the you should be getting 2000mAh back into the battery.
Thanks a bunch.
about the flight times, with my setup I'm flying 7-8 min putting back about 1700-1800mAh back into my 2200mAh pack. If you're running a 2500mAh pack the you should be getting 2000mAh back into the battery.
10-17-2008, 04:47 PM
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RE: Battery flight times - 80% rule?
ORIGINAL: AviationNut
You're supposed to take no more than 80% out of the pack for better battery longevity - leaving 20%. You would put back in 80% when you charge the pack, or 2000mAh in your case.
The theoretical headspeed = (Motor kV * Battery voltage (under load) * Pinion size) / Main gear size. This is strictly theory and the actual headspeed will be a bit lower. So, if you're using 3S lipos, headspeed = (4400kV * 10.5v (approx.) * 10) / 150 = 3080.
You're supposed to take no more than 80% out of the pack for better battery longevity - leaving 20%. You would put back in 80% when you charge the pack, or 2000mAh in your case.
The theoretical headspeed = (Motor kV * Battery voltage (under load) * Pinion size) / Main gear size. This is strictly theory and the actual headspeed will be a bit lower. So, if you're using 3S lipos, headspeed = (4400kV * 10.5v (approx.) * 10) / 150 = 3080.
You forgot to factor motor efficiency.
10-17-2008, 06:46 PM
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RE: Battery flight times - 80% rule?
Just go to www.readyHeli.com and click on their HS calculator. 
Most folks agree that well-made wood blades in good condition can take up to 3000 RPM. Anything higher than that and you need to look into good Carbon Fiber blades.
I wouldn't swing those 335's at much more than 2800, though. Realistically, unless you're doing RAD 3D, you don't need a HS higher than 2800 - 3000 RPM.
Most folks agree that well-made wood blades in good condition can take up to 3000 RPM. Anything higher than that and you need to look into good Carbon Fiber blades.
I wouldn't swing those 335's at much more than 2800, though. Realistically, unless you're doing RAD 3D, you don't need a HS higher than 2800 - 3000 RPM.
10-17-2008, 11:31 PM
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RE: Battery flight times - 80% rule?
i have run up to 3400rpm on the align 325 pro woodies and havent had one single problem. and i bang the sticks like hell too. like bryflyguy67 said unless you're doing 3D that headspeed is not necessary.
what is your current flying skills?
what is your current flying skills?
10-18-2008, 08:03 AM
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RE: Battery flight times - 80% rule?
I've just began doing FF (figure eights and stuff) so I'm still learning or better said: gaining confidence because in the sim I'm already doing loops and basic maneuvers, but I wanted to make sure that my headspeed would not be aver the woodies limit. when I'm flying FF I'm using about 80-90% power (I'm flying in idle 1) cause in idle 2 my curve is like 100%-95%-100% hehe. but I'm not going to use that for a while. I just wanted to make sure. It would suck to rip your blades apart, and from the height I'm flying (from my roof) I would want my heli dropping 80ft down into concrete without blades or the possibility of autorotation
running the 12t pinion and with .85 efficiency the head should be doing 2793rpm (the .85 is to estimate the power setting. is that number ok or should it be higher or lower')
Oh and how hot should the motor get after you finish flying? how do you know your getting good efficiency?
running the 12t pinion and with .85 efficiency the head should be doing 2793rpm (the .85 is to estimate the power setting. is that number ok or should it be higher or lower')
Oh and how hot should the motor get after you finish flying? how do you know your getting good efficiency?
10-18-2008, 06:02 PM
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RE: Battery flight times - 80% rule?
"EDIT: Another thing: what's the maximum headspeed you would run 335mm pro woodies at? At which charge do you leave a lipo overnight? Charged? Uncharged? In the middle? Thanks. " {quoted from tomtomzz}
You NEVER leave your LiPo charging overnight!! It shouldn't take more than 1 to 1.5 hours to charge up your Lipo. Hopefully this isn't what you meant; but I thought I'd throw this in here just in case ya did!
FWIW.......I charge mine about 2 hours before I leave for the flying field. About every 15 days or so, I throw all my LiPos on the charger to top them up. Just my 2 cents.
You NEVER leave your LiPo charging overnight!! It shouldn't take more than 1 to 1.5 hours to charge up your Lipo. Hopefully this isn't what you meant; but I thought I'd throw this in here just in case ya did!
FWIW.......I charge mine about 2 hours before I leave for the flying field. About every 15 days or so, I throw all my LiPos on the charger to top them up. Just my 2 cents.
10-18-2008, 10:04 PM
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RE: Battery flight times - 80% rule?
ORIGINAL: rzarikian
I've just began doing FF (figure eights and stuff) so I'm still learning or better said: gaining confidence because in the sim I'm already doing loops and basic maneuvers, but I wanted to make sure that my headspeed would not be aver the woodies limit. when I'm flying FF I'm using about 80-90% power (I'm flying in idle 1) cause in idle 2 my curve is like 100%-95%-100% hehe. but I'm not going to use that for a while. I just wanted to make sure. It would suck to rip your blades apart, and from the height I'm flying (from my roof) I would want my heli dropping 80ft down into concrete without blades or the possibility of autorotation
running the 12t pinion and with .85 efficiency the head should be doing 2793rpm (the .85 is to estimate the power setting. is that number ok or should it be higher or lower')
Oh and how hot should the motor get after you finish flying? how do you know your getting good efficiency?
I've just began doing FF (figure eights and stuff) so I'm still learning or better said: gaining confidence because in the sim I'm already doing loops and basic maneuvers, but I wanted to make sure that my headspeed would not be aver the woodies limit. when I'm flying FF I'm using about 80-90% power (I'm flying in idle 1) cause in idle 2 my curve is like 100%-95%-100% hehe. but I'm not going to use that for a while. I just wanted to make sure. It would suck to rip your blades apart, and from the height I'm flying (from my roof) I would want my heli dropping 80ft down into concrete without blades or the possibility of autorotation
running the 12t pinion and with .85 efficiency the head should be doing 2793rpm (the .85 is to estimate the power setting. is that number ok or should it be higher or lower')
Oh and how hot should the motor get after you finish flying? how do you know your getting good efficiency?
10-18-2008, 10:20 PM
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RE: Battery flight times - 80% rule?
my charger(commonsense rc) only shows Volts per cell...how do i calculate mah input?
i never go below 3.5 volts per cell when flying
i never go below 3.5 volts per cell when flying
10-18-2008, 11:03 PM
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RE: Battery flight times - 80% rule?
I rule of thumb (at least what I've noticed) is that as long as you don't go below 11.2-11.15 volts on a 3s pack which would be 3.7v per cel you will end up putting 80% back into your pack. This is always the case when I change my 2200mAh 3s pack
10-19-2008, 12:41 AM
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RE: Battery flight times - 80% rule?
Hey guys, thanks for the info. I have another question...is there any physical features that are different between the different amperage Align ESC's? I have an align ESC on here, but I don't know which one it is because there is velcro over the label. After hovering, the heatsink on top gets very hot, and I wonder if it is too low rated for the -6.
