Turnigy D2822/14 1450KV 160W Motor with 7x5E Propeller

[Mustang7302]

Ordered up parts to build a FT Duster for the wife last week (Thursday) and the powerplant parts came in yesterday from the Hobby King US Warehouse. Wanted to do a watt and current test on the bench for this combination of parts so I got the 3.5mm female bullet connectors soldered to the motor side and a male XT60 connector soldered to the battery side of the ESC. Once all of the electronic connections were ready, I mounted the motor to the end of a 1/2" square dowel (the same used for the AnyCopter booms) and clamped it down to the edge of the bench with the motor hanging off just far enough for the prop wash to clear the surface of the bench. Bound a spare receiver to the transmitter, perform a throttle calibration, and we're off to see how much power is pulled with the trusty watt meter.

Power Source: 1,300mAh 3S 20C LiPo Battery @ 12.6V
Brushless Motor: Turnigy D2822/14 1450KV 160W
Brushless ESC: HobbyKing Blue Series 20A ESC
Propeller: Master Airscrew 7x5E Propeller

Watts @ WOT: 135
Amps @ WOT: 12

The power made is in the Park 370 to Park 400 range of motors, which is perfect for the bulkier swappable planes (Baby Blender, Cruiser, Spitfire, 3D, Versa, Racer, and Duster). For less than $19 plus servos and shipping, this combination seems a good balance of power for the dollar. Once the Duster is in the air I will provide further feedback.

I also wanted to bench test the run time of this combination to get an estimate of how long to set the flight timer for. Ran the motor at 50% throttle and monitored the watt meter for battery consumption:

Start of "Flight": 35 watts of power at 3 amps
8 Minutes into "Flight": 30 watts of power at 2.5 amps; 350mAh of battery consumed
16 Minutes into "Flight": 27 watts of power at 2.4 amps; 700mAh of battery consumed
24 Minutes into "Flight": 26 watts of power at 2.4 amps; 1,000mAh of battery consumed
26 Minutes into "Flight": Battery alarm going off at 3.3v per cell; 1,100mAh battery consumed

Gentle flying could see as much as 25 minutes of flight time with this combination, but I expect normal flying (fighting wind, landings and take offs, moderate acrobatic, ect.) should run for roughly 15 minutes.

Clear skies and soft landings!

 

[Craftydan]

Mustang,

Take care with that alarm -- it let you draw down to 15% before alarming. Don't want to pick up any nasty Bixler battery habits . . .

 

[Mustang7302]

The mAh consumption shouldn't be your hard cut off number, the voltage should be. Which is what low battery alarms use to monitor. Getting down to 3.3v per cell is safe, but much past that and yes you're in Bixler puffing territory (<= 3.1v per cell). To clarify the alarm sounds at 3.3v per cell, when unloaded the cells went up to 3.4v each.

I have found all of my LiPo batteries to be over rated from 5 to 15% when you look at mAh discharge and charge rates.

 

[Craftydan]

I'm not sure I agree -- It depends on your power system.

Rest voltage of 3.7v is 20% capacity -- voltage drops *sharply* with mah drawn after that. Load voltage down to 3.3v can draw the battery below that resting voltage . . . or not, depending on the load.

While I haven't destroyed a battery using a 3.3v-loaded alarm, I've noticed severe drops in performance over short periods of time (MINUTES of flight time to alarm lost over 10 or so charges). I've since bumped mine up to 3.7v -- typically I ignore it at WOT, but ana alarm at low cruise, and I land. usuallly end up between 20-30%, and my flight-time-to-alarm has held fairly steady.

They're your lipos and you set your thresholds as you see fit, but frankly, it's that last minute of flight that shortens their lives.

 

[Flynn]

Thanks for the info Mustang

Dan, being new to certain aspects, can I ask what you use to obtain that reading? Is it an alarm sensor on the plane or a signal fed back to your receiver?

 

[Craftydan]

Flynn,

I use:

http://www.hobbyking.com/hobbyking/store/__18588__Hobbyking_2_8S_Cell_Checker_with_Low_Voltage_Alarm.html

I've got a few diffrent brand names, inlcuding a couple of these, and they all look/act almost alike -- wouldn't surprise me if they all came out of the same factroy.

Quite a few diffrent low voltage sensors floating around, but to me, only two features that are critical -- loud alarm, and adjustable voltage threashold. Set the threshold as you like, plug it into your balance port, learn when it's really done. very convienint for knowing when to land and swap that batttery.

 

[Chrizlle]

Im Running that motor with 8x4,5 prop and its on its limit. My batterie is a 3000mah 3S in my versa wing. I think it draws about 220Watts and its basicly doing fine, getting a bit warm but not too much. Flighttime is about 20min, so its not that efficient on that limits.

 

[Jaxx]

I'm not sure I agree -- It depends on your power system.

Rest voltage of 3.7v is 20% capacity -- voltage drops *sharply* with mah drawn after that. Load voltage down to 3.3v can draw the battery below that resting voltage . . . or not, depending on the load.

While I haven't destroyed a battery using a 3.3v-loaded alarm, I've noticed severe drops in performance over short periods of time (MINUTES of flight time to alarm lost over 10 or so charges). I've since bumped mine up to 3.7v -- typically I ignore it at WOT, but ana alarm at low cruise, and I land. usuallly end up between 20-30%, and my flight-time-to-alarm has held fairly steady.

They're your lipos and you set your thresholds as you see fit, but frankly, it's that last minute of flight that shortens their lives.

Dan,

I have to agree with you on this one. Everything I have read so far suggests, if we want the best performance from our lipos, we should avoid dicharging them past 80% of their mAh capacity, regardless of the voltage. 1,100mAh consumption is around 84% discharge for a 1300mAh lipo.

 

[xuzme720]

Voltage can be used as a reference but the real tale is in the mAh. Sure there is a little flexibility there, but if you want them to last, not draining them beyond 20% of capacity is the way to keep them healthy.

 

[Flynn]

Dan, always helpful! Thank you