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Author Topic: Amp draw, 6S setup.  (Read 828 times)

Offline Brent Williams

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Amp draw, 6S setup.
« on: May 31, 2020, 11:49:16 PM »
I have several Castle Edge Lite 50 and Edge Lite 75 ESC's on hand.  I will be using a Cobra 3520/14 with a Thunder Power 6S/2800 battery and the Hubin FM9 timer in my upcoming e-converted Sultan.
 
The Cobra 3520/14 has a max continuous current draw of 46 Amps.   4 amps of fudge room seems like a pretty safe margin (to me) to use the lighter Edge Lite 50 ESC.  However,  I see many folks using the larger 75amp ESC in these big power combos.  For you electronic engineer types, does that seem like a reasonably safe margin? 
It will have very good airflow over the ESC, as I am mounting the ESC in the vacant pipe tunnel.
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Offline John Rist

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Re: Amp draw, 6S setup.
« Reply #1 on: June 01, 2020, 02:31:30 AM »
Looking at the prop chart for a Cobra 3520/14 an APC 10x7-E prop will draw 36.7 A at 12,081 RPM.  Assuming that you are using a settable RPM setup and are setting the RPMs at 9 to 10K RPMs the amp draw will be less than 36A.  So I would say that the 40 amp ESC would be a safe choice.  If you are tail heavy and need noise weight use the bigger ESC.  In short ESC amp ratings, for the most part, are the true maxim working rating.   Most all ESC also have a short term over-current rating to allow for current spikes during motor start up.  Also if you check the AMP draw with an amp meter on the ground the amperage will drop when airborne as the motor unloads. 
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Online Crist Rigotti

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Re: Amp draw, 6S setup.
« Reply #2 on: June 01, 2020, 07:20:24 AM »
Quote from: Brent Williams on May 31, 2020, 11:49:16 PM
I have several Castle Edge Lite 50 and Edge Lite 75 ESC's on hand.  I will be using a Cobra 3520/14 with a Thunder Power 6S/2800 battery and the Hubin FM9 timer in my upcoming e-converted Sultan.
 
The Cobra 3520/14 has a max continuous current draw of 46 Amps.   4 amps of fudge room seems like a pretty safe margin (to me) to use the lighter Edge Lite 50 ESC.  However,  I see many folks using the larger 75amp ESC in these big power combos.  For you electronic engineer types, does that seem like a reasonably safe margin? 
It will have very good airflow over the ESC, as I am mounting the ESC in the vacant pipe tunnel.

How much does the airplane weigh?
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Offline William DeMauro

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Re: Amp draw, 6S setup.
« Reply #3 on: June 01, 2020, 07:33:51 AM »
Unless you going to run a monster prop on that motor I doubt you will ever have a problem with the Ice 50 . I ran that exact combo on my SV 22 and my Voltron for a bunch of years. I ran 11 and 12 inch 3 blade props(cox ressinger props) and APC 13x4.5 and 13.5.5 without issue. I still have that setup in my Sv22 even though I haven't flown it in a few years. The prop and rpm are the biggest factors here in determining the ESC. If the plane is light enough you can most likely run the 3518/18 740KV motor without issues. We have run that motor in almost 70 ounce planes.
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Offline Brent Williams

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Re: Amp draw, 6S setup.
« Reply #4 on: June 01, 2020, 09:00:10 AM »
Thanks guys, I think the Edge Lite 50 will suffice and be safe.  The plane should weigh around 60oz (or slightly less) ready to fly.  I'll use a 2-blade prop at first, either APC or Xoar.

Pretty excited to get this plane in the air soon.
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Online Fred Underwood

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Re: Amp draw, 6S setup.
« Reply #5 on: June 01, 2020, 10:51:50 AM »
My two cents a bit late.

Another way to consider the average amp draw is to look at amp usage in a flight.  Round numbers are 2000ma in 5 minutes or 400ma/minute, or average draw of 24 amp.  I purposely estimated a little high and I actually use about 20 amp/h.

In addition with an active timer adding acceleration, my peaks were still only about 40-45 for very short times (data-logged) and Castle 50 was adequate.  More capacity in the ESC typically also has more heat handling ability, so some may use the larger esc for that reason.
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Offline Tim Wescott

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Re: Amp draw, 6S setup.
« Reply #6 on: June 01, 2020, 11:23:54 AM »
Quote from: Fred Underwood on June 01, 2020, 10:51:50 AM
... Another way to consider the average amp draw is to look at amp usage in a flight.  Round numbers are 2000ma in 5 minutes or 400ma/minute, or average draw of 24 amp.  I purposely estimated a little high and I actually use about 20 amp/h. ...

That's for one particular plane (really, one typical stunter at one particular weight), but yes.
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Online Fred Underwood

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Re: Amp draw, 6S setup.
« Reply #7 on: June 01, 2020, 12:30:42 PM »
I realize the generalization, but his Sultan, 6S 2800, Cobra 3520/14..... all seemed to be that typical stunter.  :-)
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Offline William DeMauro

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Re: Amp draw, 6S setup.
« Reply #8 on: June 01, 2020, 01:08:25 PM »
Quote from: Brent Williams on June 01, 2020, 09:00:10 AM
Thanks guys, I think the Edge Lite 50 will suffice and be safe.  The plane should weigh around 60oz (or slightly less) ready to fly.  I'll use a 2-blade prop at first, either APC or Xoar.

Pretty excited to get this plane in the air soon.
If that plane is really around 60oz with battery then your ICE 50 should be fine, You will also have no trouble dropping down to a 3515/18 motor if you want. A 2 blade prop in the 12x5, 12x6 range should work fine, APC or Xoar. From experience, you should use somewhere between 1700 and 2000 mah out of your batter depending on line length, weather condition and actual settings
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