lsjpeng

I got two packs Tenergy 5S 4450 22C LiPo batteries from Xus Hobby (http://www.xushobby.com). As they told me, this is their new product that still not shown in their product list. In short, it is very cheap, only $150 a pack (not sure the final retail price will be), so I deicided to give it a try. Here is the preliminary test result.

Setup:
Airplane: Focus II
Motor: Himax 6320-230
Prop: APC 20x15E
Battery weight 21.7 Oz per pack
Total take-off weight: 12 lb.

I had a Watts-Up in one flight that gave me the peak power and current during flight, and power usage as well.
The motor was running smooth, flying characteristics were no difference as expected.
Pix below show the data after one whole Master sequence:
Max current: 82.93A
Max power: 2772.3W
Usage: 3793 mAh (in light wind day)
After flight, battery surface temperature was barely warm.

Overall, I'm happy with the performance. The next data I will collect is how robust the battery is, I will follow up after I have 50 flights or more.

Luke

patternflyer1

My Feedback: (11)

Good Job Luke..

Great info.

Chris

lsjpeng

Eagle Tree eLogger data chart on 1/26/08.
After finished one Master sequence and landed, I tached 5600 rpm at full throttle (APC 20x15E), pretty good for this cheapy battery!

Derek.Koopowitz

Luke,

Have you tried other props with that motor? 89a seems like a lot of draw... how about a 20x12?

-Derek

lsjpeng

I wish it was 89A..... It's 84.2A at maximun.

Here is another data for you. APC 20x13 (sorry, I don't have 20x12).
Current draw was ~2A lower. Peak current was 82.47A.
It turns out 20x13 flys better than 20x15. Overall speed is slower, easier to handle. One Master sequence usage ~3600 mAh.

Magne

3600/4450=0,80
80% discharge is regarded as the maximum acceptable for long term survivability for Li-pos.

If I understand your above graph correctly, you discharged 4170 mAh from the 4450 mAh pack. This is almost 94%, which may cause premature failure of your packs.

Personally, I think that 4450 mAh is way too small a pack anyway, but that is just me. I have always used 6000 mAh packs.
(Which did not last very long either. But that is also just me.)

Magne

lsjpeng

Hi Magne:

You have sharp eyes!
Yes, I did four extra vertical maneuvers after I finished the Master sequence. If I land right there, it will be ~3600 mAh.
Although, I still working on my throttle management, I'm pretty sure I can reduce some more usage.


Luke

lsjpeng

Data from APC 19x12WE prop.

Since the 20" props draw too much curent, and fly too fast that I have to cut back throttle all the time, so I tried 19x12WE today. The result was good.

I set throttle upper ATV to 75%, flght characterics have no difference, battery usage dropped to ~3400mAh or lower (for one Master sequence). Max current down to ~78A. Overall, the performance improved significantly.

Magne

Hi Luke.
What RPM's are you getting with the 19x12WE at 78A?

Regards,
Magne

lsjpeng

6600 rpm.

Luke

Magne

Luke.

You have provided some very interesting information here, thank you.
Looking at Himax's webpage, I can only find two motors that are of this power level.
These are 6320-250 (Kv= 250, 450 grams, 1700 W) and 6332-230 (Kv=230, 690 grams, 2200W)
I can not find a 6320-230, and wonder if this is a misprint in your original post? Please clarify which motor you have got.
Most motors used for this size models weigh more than 450 grams. If you have the 6320, then this is an interesting option.

Regards,
Magne

lsjpeng

Sorry, that's a typo. My motor is 6332-230.

The data I have so far are under light wind condition. I'm more interested to see what impact will be in a windy day. I will update when I have data.

Luke

OhD

Luke,

The batteries look very good. The ability to stay above 33 volts with 85 Amps is impressive. I wish they were a little lighter.

However, your system does not look good. I don't know if it is the motor or the ESC but the current seems way too high. I'm flying a 22x12 on a Dual Sky 6360 12T and am pulling less than 60 Amps. Granted my recently abused TP Prolites sag but I believe I'm still turning more than 5600 as the airplane is flying great. I can also get through the Master's pattern at less than 3000 mAh. I'd try to figure out why your current is so high.

OhD

lsjpeng

You are absolutely right, my motor is almost two years old. It was damaged twice. Although not so efficient as before, it still runs OK to me. Your Dualsky 6360 12T data are great, maybe I should get one! Thanks for your input.

Luke

Magne

OhD,
It would be very interesting if you could measure the revs you are getting on the ground with your set-up.
From your graph (a bit difficult to read) I think you are operating at max. 57.91A at about 31-32Volt.
That is approx. 1800W.
(Luke is operating at 78A @ 33V with the 19x12WE, that is approx. 2575W, which is very high. Maybe he has more power than really needed?)

However, based on Pe Reiver's prop-power calculator, a APC 22x12 at 5600 rpm requires approx. 2325W.
(According to the same power calculator, 5150 rpm would require about 1800W. That's why it would be interesting if you could measure your revs, as I regularly use this calculator for comparison.)

Regards,
Magne

OhD

Magne,

I had the same question so last weekend I installed my Spin 99 ESC that had the Eagle Tree Brushless tach wired in. I got nothing but noisey data so I pulled it out and put in an Eagle Tree optical tach. I went out today and got some data.

Run up on the ground with TP Prolite with 164 flights on it. Spin 99 and APC 22x12:

Eagle tree Data
67.79 Amps at 35.21 Volts
5641 RPM

Masters sequence with no extra maneuvers:

Maximum In-flight current:
58.02 Amps at 33.13 volts
5339 RPM

Total mAh 2338
Total charge after flight 2680 mAh

Spin Box data:
Max current 61 Amps at 34.58 Volts (Probably during run up on ground)
Maximum RPM 6160 (Probably unloaded)


I also tested my new never flown $110 battery packs
Run up on ground:
74.9 Amps at 37.46 Volts
5889 RPM

In Flight:
Max Amps 64.71 at 35.75 Volts
5658 RPM

Today was much warmer and the battery packs were warmed prior to the flights by sitting in the sun on my dashboard. However it is interesting that the in flight power was similar.

At first glance it looks like your prop power calculator is very accurate. How can we get it or the equations behind it. I have always felt the prop data was the missing link.

Regards, Jim Oddino

OhD

I found the prop power calculator. This is going to be a lot of fun.

I'm starting to think along the lines that we could use smaller batteries for competition. Save weight and cost.

Jim O

OhD

Magne,

What prop constant do you use for APC-e props?

Jim O

OhD

The measured data is almost too close to the Prop power calculator calculations to believe:

------------ Calculated ----- Measured ----- RPM

Battery 1 ----- 2398 -------- 2387 --------- 5641

Battery 3 ----- 2571 -------- 2567 --------- 5791

Battery 4 ----- 2703 ----- --- 2804 --------- 5889


I will have to fly many flights to see if I consistently use the same power over a variety of conditions. But it sure looks like I could use smaller batteries and maybe even a smaller motor. The average Watts are pretty low.

Jim O

elan120

My Feedback: (1)

Jim,

What prop constant did you use to get the calculated data? Do you think different prop size will have different prop constant?

Thanks,
Kevin

OhD

I used 1.2 but I believe that is for a standard APC prop for a glow engine. The E props are obviously different but I'm not sure in what direction. I don't think changing the prop size affects it as long as the shape, thickness etc. are similar. You can see that the APC narrow and wide props have different constants but all sizes of narrows would use the same value.

The 1.2 is probably high, because it makes it look like the motor is 100% efficient.

elan120

My Feedback: (1)

Jim,

Thanks. I also find this calculator provides very good data. Meanwhile, what do think cell I-18 and I-36 are for?

Kevin

OhD

It looks like they do have a correction that takes into account the diameter and pitch. I stand corrected.

Jim

Magne

I use 1.2 as well for the standard E-props. I also use 100% efficiency, to get results very close to the measured values.
In reality, the prop koefficient should possibly be lower, and the efficiency certainly is not going to be 100%.
But without altering these values, I still get good results for comparing the effect of diferent loads, revs. etc.
I have also used this calculator for gas engines, comparing one make of propeller to another. It does work.

However, if I use the 1,2 factor for the standard APC-E propellers, then I think that 1,5 load factor is too high for the APC-W propellers.
In reality I measure lower power levels than calculated values. (1,35 seems to match measured values to calculated values, testing a 19x12W and a 20.5x12W)

I am currently testing a 10s2p A123 (4600 mAh) pack, to see how this compares to 10s Li-pos.
I have a Hacker C50 12XL motor, with a Kv=1353/6.7=202 rpm/V.
Due to the lower voltage of the A123 batteries, I only get about 5400 rpm and 54A with a APC 20x13E propeller.
Enough to make it fly, but not really powerful enough.
I either need a significantly larger propeller, or a different motor with a higher Kv value.
(I have ordered a APC 21x14E and will try this asap.)

Looking at alternative motors, Hacker make different wind motors in the "old" C50 series, but limit their choice to 13, 14 and 15 wind for the Competition series, so this is no option.
I need a light weight option here, due to the increased battery weight.
Dualsky make a 6350-12T with a Kv=310 @ 470 gram.
Himaxx make the 6320-250 @ 450 gram.

Anybody got experience with either of these motors, or any other suggestions?

Regards,
Magne