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e-Electric General Discussion > Electric Guru please evaluate performance data
 
 
Dan A.
Senior Heliman
Location: Rancho Santa Margarita, CA

I need a hard 3D electric guru to evaluate my battery performance and tell me what is the biggest killer? I'm sure I need to adjust something (pinion, pak size, radio curves, flight timer, or other) in order to get more reasonable battery life. I hear others getting 100 to 200 cycles of 3D flights on their lipos, while I'm consistently only getting 39 flights before battery death. That equates to $6.50 per flight. MY GOAL: significantly lower the $/flight ratio without sacrificing much 3D performance.

Logo 10C
Neu 1910 1Y fanned 1020 kv
21 tooth pinion (9.524 gear ratio)
TP6S1P 3800mAH Extreme series
CC HV85 ESC
+-11 degrees collective
+-7 degrees cyclic
5 minute flight timer

Comparative FDR information:

When the pak is new, average headspeed=2350, high amps=60, 1200W, low pak V=19.8, 2300 mAH, high temp=138, flight time=5.5 minutes

39 flights later, average headspeed=2200, high amps=45, 858W, low pak V=17.2, 1200 mAH, high temp=121, flight time=3 minutes

The most significant factor in my mind is how much the pak volts are dropped during flight. From 25V at no load, to 19V in the middle of a flight. I believe the belt has just the right amount of slack, with occasional momentary slap. I believe the gear backlash is perfect also (judged by slight movement with fingers).

What would you change?
08-19-2008 04:38 AM
 
 
helimatt
Elite Veteran
Location: Lafayette, IN

Couple things I would change there:

Fly shorter flights or use higher mAh packs- you are simply over-tasking the pack. Are the cells hot after you land?

Plus, there may be better packs than the TP extremes, try the newer Outrage packs (I plan to), or Airthunder if you can lift a fat 5000mAh pack because they don't have as wide a selection of capacities as other makes.

Basically, though you are not exceeding the pack discharge rating, I think you are simply asking a lot of a 3800mAh pack.

Never, ever, ever, ever give up.
08-19-2008 01:03 PM
 
 
red_z06
Elite Veteran
Location: Dumont, NJ

Most importantly, what was the pack voltage after each flight? They should be 21v-22v range to not taxi the pack too much. If you maintain 20% reserve (with above pack voltage), then 5.5min flight tells me that you are only pulling average of 10-12c which is not hard for extreme series.

The beggest killer of lipo health is pulling the pack down below 20% too many times.

4min flight = 15c
6min flight = 10c

Idealy, if you get 6min flights, your pack will last longer than when doing 4min flights to 20% reserve. You will notice at least 10% performance gain if you go to v2 packs as the voltage does not drop as much as v1 extreme.

www.justinchi.com
08-19-2008 05:02 PM
HOMEPAGE  
 
 
Dan A.
Senior Heliman
Location: Rancho Santa Margarita, CA

Thanks for the info and advice guys.

When I look closer at the FDR chart it looks like I'm killing the paks DURING flight. Not just by running too long.

I'll try 19 tooth first and see what headspeed I can get.

After these packs reach EOL, I'll change to 8S configuration. 8S is a little higher voltage than the 1910 1Y stator was designed for, but Steve says it should be OK if I keep the motor speed under 30000. I used to run 8 emolis which is almost that high (like 7S lipo).

Cheers
08-21-2008 01:10 AM
 
 
Dan A.
Senior Heliman
Location: Rancho Santa Margarita, CA

Update:

So far, I've made the following changes:

  1. Replaced the pinion with a 19 tooth pinion. Some good results ... headspeed controlled in a tighter band (less bogging) at approximately 2100 RPM. Pak voltage doesn't drop as low. However, amps spiking much faster than stick demand changes.
  2. Slightly increased backlash in both front and rear pinions. Perfect amount. Result ... no change in amp spiking.
  3. Lowered governor gain setting from 80 to 50. Result: no appreciable difference in amp spiking and headspeed control.

Maybe my motor is starting to short? Is that a plausible failure mode or normal wear symptom? Is the amp spiking consistent with possible motor shorting?

What do you recommend next?

08-31-2008 02:19 AM
 
 
MrMel
Elite Veteran
Location: Lidingo, Sweden

New motor + Outrage batteries.

Something is wrong with your motor, you shouldnt see that kind of spiking, and if its long enough to register by the EagleTree its long enough to hurt the batteries.

Second, Outrage or DesirePower battries, they hold an avg about 10% higher voltage, meaing lower ampdraw, meaning more flighttime for same amount of mah.


Team Autopartner - Team pilot
09-03-2008 07:59 PM
 
 
Dan A.
Senior Heliman
Location: Rancho Santa Margarita, CA

MrMel,

I wish you had told me that a couple days ago. My motor stopped suddenly and the Logo dropped straight down out of the sky before I could react. The flight data showed excellent headspeed control. Amps suddenly dropped first, then RPM fell off to zero. A few seconds later, the amps tried to rise a little, followed by a few RPM. That's approximately when I flipped to throttle hold before it hit the ground. Motor turns as easily as ever by hand (no seized bearings). Some tail twitching was noticable prior to the failure (I still don't know what this indicates). No other hints of the impending failure were apparent to me. Radio functioned fine at the crash site (all servos moved and gyro controller reads good voltage).

The motor is a Neu 1910 1Y with 432 flights. How many flights are these motors usually expected to endure?

What is the specific failure mode of the motor that can cause amp spiking? Some sort of conductive dust shorting out the current? I find it difficult to believe an intermittent open winding/connection would look like constant spiking (I think an intermittent open would usually appear more erratic, unless fed by continuous vibration).

Other pilots sent me some flight data traces that showed higher amp spikes than mine.

Besides visually inspecting everthing carefully, I'm not clear what to do next in order to narrow down the cause.
09-04-2008 03:42 AM
 
 
MrMel
Elite Veteran
Location: Lidingo, Sweden

Ouch,

Im not sure what can cause it, you need to send a mail to Steve Neu and ask, of course, it could be the controller too, but I find that rather unlikely.

I only had 400+ flights on one motor and that was a Kontronik Tango, I usually try around motors quite often so I dont get that many flights on them, but I had a fair share of failed motors too, many of them neu, but none burning up or stopped working (that have only happened with hackers for me)

Contact Neu and see what he can do, if Scorpion 4020 motors arrive soon, try one, they are cheap and scorpion has proved them self in the motor making buisiness.


Team Autopartner - Team pilot
09-04-2008 04:09 AM
 
 
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e-Electric General Discussion > Electric Guru please evaluate performance data
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