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Great Planes 81" Yak 54 E power system?

Old 07-17-2011, 06:12 AM
  #26  
kyleservicetech
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Originally Posted by Larry3215 View Post
Looks like you got lucky. That could have easily cost you the entire model.

Its a Turnigy controller.

Its interesting to me that the HV versions of the knock-off controllers seem to fail at much higher rates.

That's interesting.

I've been running the Castle Creations ESC's now for 5 flying seasons. All but one has performed perfectly. The microcontroller quit on the ESC that failed, after several years of flying with it. CC fixed it for $45.

And, I'm running these ESC's right at their maximum current rating, maybe even a little over ? (But you never, never, never ever operate any of these ESC's over their maximum voltage range!)
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Old 07-17-2011, 07:13 AM
  #27  
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Yeah, most electronics can tolerate even moderate over currents with adequate cooling.

Voltage limits tend to be zero tolerance
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Old 07-17-2011, 01:14 PM
  #28  
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Yes I always run seperate power, and this esc doesnt have a BEC.

Its a Turnigy 120 HV Opto..................never again.

And yes I do agree it could have been alot worse....I`m lucky.

The Turnigy Brain 100 is the one Im using now with great results.
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Old 07-17-2011, 01:19 PM
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It flew with tons of power after removing 1.25 lbs from the model and adjust ing CG.

It went vert unlimited.........Current draw on the ground was only 75ish amps 3700 watts so I was well within range.
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Old 07-18-2011, 02:57 AM
  #30  
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I'll only say this one more time then I'll leave you alone

Its not possible to pull 3700 watts from a 12S setup on only 72 amps.

3700/12 = 308.33

308.33/72 = 4.282 volts per cell

The only way to get 3700 watts on a 12S setup at 72 amps is if the pack voltage goes UP under load!

Not gonna happen

If you are actually getting 3700 watts, then you are pulling a minimum of 83 amps and probably closer to 90 something.

If the amp number of 72 amps is correct, then you cant be pulling more than about 3200 watts.

Like I said before, the math just doesnt work.

Either your meter is not working properly or your measuring things the wrong way.
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Old 07-18-2011, 03:10 AM
  #31  
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Originally Posted by Larry3215 View Post
I'll only say this one more time then I'll leave you alone

Its not possible to pull 3700 watts from a 12S setup on only 72 amps.
Either your meter is not working properly or your measuring things the wrong way.
Yup
Only way to measure watts on our stuff is with an inline wattmeter such as Astroflights, among others.

Or, with a clamp on DC ammeter such as Sears Craftsman #82369. Only problem with this measurement, you need to measure the current with the clamp on DC ammeter, AND at the SAME time, measure the voltage at the input of the ESC with a DC voltmeter. The battery voltage will sag with the 80 Amps load. That voltage sag will affect your power calculation of Power equals volts times amps.

Doing this with a 3 KW motor equipped with a propeller requires a bit of care, and likely someone to help out. The prop blast will likely blow your meters all over the place. (Don't ask )
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Old 07-18-2011, 04:24 AM
  #32  
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I have an Eflite watt meter ??
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Old 07-18-2011, 04:43 AM
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Originally Posted by flyer88 View Post
I have an Eflite watt meter ??
H'mmm
As Larry indicates, I'd be tempted to put your meter in series with another wattmeter known to be accurate.

Something's wrong, no LiPo cell will put out 4.2 volts at 72 Amps.

(Unless you're running two 7 cell Lipos in series )

Generally these meters are fairly accurate. My Astroflight wattmeter has been checked against my $350 Fluke 87V meter, and its within a percent or two. (FYI, that Fluke meter is accurate to 0.2%, far more accurate than what's needed for our models.)
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Old 07-18-2011, 06:25 AM
  #34  
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Originally Posted by flyer88 View Post
I have an Eflite watt meter ??
If thats what you're using to get those readings, then its way off.

If its still in warranty, Id see if you could get it exchanged.

Those are not the best watt meters on the market, but they are usually closer than that.
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Old 07-19-2011, 03:48 AM
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Originally Posted by Larry3215 View Post
If thats what you're using to get those readings, then its way off.

If its still in warranty, Id see if you could get it exchanged.

Those are not the best watt meters on the market, but they are usually closer than that.

I just checked my watt meter against my DVM and they are within .1 of each other. Watt meter read 22.7 DVM read 22.8
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Old 07-19-2011, 04:04 AM
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Originally Posted by flyer88 View Post
I just checked my watt meter against my DVM and they are within .1 of each other. Watt meter read 22.7 DVM read 22.8

You need to verify both the voltage AND the current on your watt meter with a separate wattmeter known to be accurate when your motor is wound up to full power. Could be your measured current is off. That would not be a good thing for your motor/ESC/battery if you're pushing their ratings.

Unfortunately, DVM's usually don't measure currents above 10 Amps or so.
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Old 06-06-2012, 11:35 PM
  #37  
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Update: been running a castle 120 hv in the yak with perfect results.
No timing or sync issues and 4000 watts on 12 s running a carbon 22x10 pt electric. Perfect setup !
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