Nov 17, 2012, 10:44 AM The Earth got in the way! United States, OH, Canal Winchester Joined Feb 2007 6,438 Posts Wait that was the battery max amp draw formula. (C x mAh = max continuous amps) Last edited by kuczy; Nov 17, 2012 at 10:55 AM.
Nov 17, 2012, 10:57 AM
E sailplane thermal hack
USA, CA, Chico
Joined Feb 2011
3,807 Posts
Quote:
 Originally Posted by kuczy C rating x Mah = the battery's max continuous amps So (1350mAH 30C Lipo Battery): 1.350AH X 30C = 40.50Amps Max Constant (2200mAH 30C Lipo Battery): 2.200AH X 30C = 66.00Amps Max Constant
My understanding is MAH x c rating gives highest current or wattage battery can deliver,,, but with same load on bigger battery ( bigger mah ) battery might deliver slightly more wattage,, cause all other things equal the bigger capacity battery will have lower internal resistance,, I believe the higher C rated batteries also have lower resistance relative to a lower C rated battery of same size. That's why under a given load the higher C rated battery will run cooler. You electrical engineer types out there, please correct me if I've got that wrong. :-)
In one of the recent electric flight magazines there was an article where they tested batteries of Same mah capacity but different C rating to see difference in output. The surprising outcome in the test ( at least to me ) was the 65c battery had almost same output as the 45c battery but with noticeably more weight. Interesting!!!
Another thing I've noticed in my own experiences, is if ESC has good airflow over it usually can easily take its full continous rated capacity for full duration of a flight ( in general ),, I once had an unfortunate experience with a parkzone Spitfire whereby I upgraded to a bigger higher pitched prop,, when I checked amp draw static it was at 29amps with a 30amp ESC , I figured prop would unload in air reducing amp draw a bit and I'd be fine,,, WRONG!!!!! I wasn't accounting for the fact that ESC on that plane was completely encased in foam with ZERO airflow over it. I was alright for a FEW flights,,,,, but then disaster struck!!! :-O,,, on one flight right after takeoff I noticed smoke billowing out of the plane,, she came right down with ESC blazing on FIRE!!! I ran over reached into the flames and yanked the ESC wires saving the plane from almost a certain fiery death. ,,,, LESSON LEARNED

Jerry
Last edited by Airman74; Nov 17, 2012 at 11:12 AM. Reason: Addition
 Nov 17, 2012, 10:57 AM certified crash instructor Scottsdale Arizona Joined Dec 2009 2,221 Posts Those tests were done static with a watt meter. I have a feeling 2s will pull around 12 amps, might need 30-35c lipos and 12 amp esc for 2s, I'll know in a few hours.
Nov 17, 2012, 11:23 AM
E sailplane thermal hack
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Joined Feb 2011
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Quote:
 Originally Posted by slo-fly Those tests were done static with a watt meter. I have a feeling 2s will pull around 12 amps, might need 30-35c lipos and 12 amp esc for 2s, I'll know in a few hours.
I'm wondering if your gona have trouble getting to the correct CG with the lighter 2S battery,, on mine at least I found that with my 48gram 3S battery , I had to shove it completely all the way fowArd to get it to balance at correct CG. In fact,, I'm thinking this will make trying 4S easy. :-)
I'm glad I didn't just go out an try an fly it without checking CG with battery all the way back!!!
Cause when I checked CG with it there it was off ( too far back ) considerably. I'm guessing those two servos mounted in the tail is what's causing this.

Jerry
Last edited by Airman74; Nov 17, 2012 at 11:26 AM. Reason: Addition
Nov 17, 2012, 11:23 AM
Registered User
United States, CA, Mt Shasta
Joined Jun 2010
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Quote:
 Originally Posted by Airman74 Don't know yet,,, got any ideas???? But trust me ,,,,, if there's ANY break at all in the rain tommorow,,, she/he is goin UP!! :-)
I was thinking for you that you could call the little dude Airman jr. Wow...I never though she/he! Very PC of you. My wife loads air-tankers for CalFire and their tanker pilot is a she. I should know better.
Daunting weather for a maiden here in N Cal. Lots of high wind warnings through Monday. I'm setting here waiting to try my new 2300/5043 combo and the leaves outside are blowing sideways.
Mike
Nov 17, 2012, 11:41 AM
E sailplane thermal hack
USA, CA, Chico
Joined Feb 2011
3,807 Posts
Quote:
 Originally Posted by shastamike I was thinking for you that you could call the little dude Airman jr. Wow...I never though she/he! Very PC of you. My wife loads air-tankers for CalFire and their tanker pilot is a she. I should know better. Daunting weather for a maiden here in N Cal. Lots of high wind warnings through Monday. I'm setting here waiting to try my new 2300/5043 combo and the leaves outside are blowing sideways. Mike
Yup,,,, same here!! :-(

Jerry
 Nov 17, 2012, 11:47 AM certified crash instructor Scottsdale Arizona Joined Dec 2009 2,221 Posts I'm planning on removing the pilot and tinting the canopy to help the CofG with 2s, might need to move esc forward if I can find a spot for it.
Nov 17, 2012, 12:10 PM
Registered User
United States, CA, Mt Shasta
Joined Jun 2010
3,135 Posts
Quote:
 Originally Posted by slo-fly I'm planning on removing the pilot and tinting the canopy to help the CofG with 2s, might need to move esc forward if I can find a spot for it.
Ya..but who's going to fly the plane?
Mike
 Nov 17, 2012, 12:27 PM certified crash instructor Scottsdale Arizona Joined Dec 2009 2,221 Posts All my planes are ghost flyers, I'm still gonna name it slimer, the green ghost from ghostbusters!
Nov 17, 2012, 12:43 PM
E sailplane thermal hack
USA, CA, Chico
Joined Feb 2011
3,807 Posts
Quote:
 Originally Posted by slo-fly I'm planning on removing the pilot and tinting the canopy to help the CofG with 2s, might need to move esc forward if I can find a spot for it.
That might work,,, let us know what you do and how it all works out.
Slimer,,,,, I LIKE it!!!!
Plus looking at battery cavity I'm sure you noticed there's a little opening you might be able to carve out a little bigger to move. Smaller 2S battery even further fowArd
Last edited by Airman74; Nov 17, 2012 at 12:45 PM. Reason: Addition
Nov 17, 2012, 01:01 PM
big ignore list
United States, CO, Longmont
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5,279 Posts
Quote:
 Originally Posted by slo-fly My edge pulls 112 watts @ 9.9 amps with a hyperion 25c 450mah 3s. I'm getting a few vibrations, prop probably needs balancing. I removed the y harness and put a 12 amp esc in, all up weight with hyperion 3s 450mah is 8.1 ounces, 7.7 ounces with hyperion 2s 450mah. I will do some 2s testing in a few hours and hopefully get a maiden in. I'm guessing it's probably going to be around 90 watts on 2s with apc 8x3.8 slow fly prop.
thank you for posting!

Quote:
 Originally Posted by flyrtim hmm 9.9 amps with a 450 3s. So a 800 3s with stock esc doesn't sound so good. thanks for that info ! yes, curious about the larger 2s just checked out the spec page on the stock 10 amp esc. "says continuous maximum current 0-25amp" ? ? how is this possible?
this was on static testing and that will pull more... also the motor will only pull what it needs to run, and no more

Quote:
 Originally Posted by kuczy FYI John Redman has said on several different threads that E-Flite motors and ESCs are way under rated. That doesn't mean you can run 4s on the stock setup though.
could be because in flight they pull less amps than on the ground in static testing...
and 4s will be had by a few of us

Quote:
 Originally Posted by bobly Not sure I understand. In theory if a motor pulls 9.9 amps with a 450 ma battery, it will pull 9.9 amps from a 2000ma battery. The only reason it would not is if the 450ma battery did not have the discharge capacity (high enough c rating) to get full power from the motor. At least that's how I see it. 450ma vs 800ma is the capacity of the fuel tank, more fuel, but not necessarily more powerful fuel. Shouldn't a 450ma battery with a 25C continuous rating be able to dump out 11 amps continuous? Also, were you measuring amp draw in static conditions or did you have telemetry to see what it was doing unloaded in the air?
the motor will only pull what it needs to run..
it is possible this more will pull more amps with a higher C rated pack because it allows the motor to run up more

now how big a pack can I put in this bad boy?
I have a Gens Ace 800mah 3s
 Nov 17, 2012, 01:12 PM The Earth got in the way! United States, OH, Canal Winchester Joined Feb 2007 6,438 Posts You can run 4s on the stock ESC and motor all day in yours, but I smoked a Park280 on 3s already once this season..... To each their own.
Nov 17, 2012, 01:16 PM
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Quote:
 Originally Posted by kuczy You can run 4s on the stock ESC and motor all day in yours, but I smoked a Park280 on 3s already once this season..... To each their own.
I'm going to fly mine with a tad smaller prop....
little less diam.
I can't imagine the sounds this sucker will make
 Nov 17, 2012, 02:25 PM E sailplane thermal hack USA, CA, Chico Joined Feb 2011 3,807 Posts Just had a tiny break in rain,, took her out to local field, wind gusting 20-27 mph prob not my best idea,, she flew fine but was quite a handful in that wind,, flew about 2 min,, she had planty of power very smooth control response with rates on high and reccomended amount of expo,,, landing was tricky got very very turbulent close to ground,, did kinda a rough landing not too bad. Gona have to wait for wind to calm down a little :-)
 Nov 17, 2012, 02:30 PM Registered User United Kingdom Joined May 2012 221 Posts OK i just watched the promo video twice and the seth clip 3 times!!! Will someone pleeeaaassseee fly the 540 and film it Even a few pics would be nice to stop me going crazy while waiting for the UK to get some stock. When i get mine i'm going to try and shoehorn a 850 3s pack in there just for fun! I've got the 450s on order too Cheers guys