Author Topic: Battery comparison. (Read 2585 times)

TDM · « **on:** June 04, 2010, 06:59:05 AM »

There is not a whole lot said about battery quality and reliability. When we choose a battery for our planes we are making choices between a brand or another some batteries cost 4 times more than other yet do we get our money worth. TGY batteries are cheap but how reliable are they and do they deliver the goods? We are tempted to believe more expensive is better but is it true? So I am opening the debate here.
What are we using and why?

Paul Walker · « **Reply #1 on:** June 04, 2010, 09:55:36 AM »

Quote from: Traian Dorin Morosanu on June 04, 2010, 06:59:05 AM

There is not a whole lot said about battery quality and reliability. When we choose a battery for our planes we are making choices between a brand or another some batteries cost 4 times more than other yet do we get our money worth. TGY batteries are cheap but how reliable are they and do they deliver the goods? We are tempted to believe more expensive is better but is it true? So I am opening the debate here.
What are we using and why?

Don't forget to consider weight in this trade. Yes, there are many cheaper batteries out there, but they are usually noticably heavier for the same capacity. Weight is very important to me.....cost.....not the highest on my list.

Paul Walker

John Witt · « **Reply #2 on:** June 04, 2010, 11:11:53 AM »

Thunder Power 5S 2600 20C = 284 g (10 Oz) @ $105 each (Internet source, don't remember who)

Zippy 2650 5S 40C from Hobby King = 458 g (16 Oz) @ $40 each

Zippy 3000 5S 20C = 439 g (15.5 Oz) @ $25 each

Note capacity and discharge rate differences.

John W

Kim Doherty · « **Reply #3 on:** June 04, 2010, 12:09:21 PM »

Dorin,

Without question the highest energy density per gram of mass are the Thunder Power Pro Lite V2 series cells. Lifespan is as good as any other similar pack. To use something else is to compromise.

Kim.

bob branch · « **Reply #4 on:** June 04, 2010, 12:31:20 PM »

It is not a compromise if you have had Thunder Power packs before and they all crapped out inside of 6 months in CL use. They were not handled by an electric newbie, but by someone with a number of years of experience with lipos. Are they today's cells? No. but they were garbage. Having had that experience to use somehting else may be a compromise to someone else but not to me being the guy who had it happen. Of note, one of my flying partners had same experience with same vintage of the same packs. Neither of us have much interest in using them again.

bob branch

Paul Walker · « **Reply #5 on:** June 04, 2010, 01:04:28 PM »

It is not a compromise if you have had Thunder Power packs before and they all crapped out inside of 6 months in CL use.

Very interesting, and troubling. How many flights did they have on them when they "crapped" out?

Paul W

Mark Scarborough · « **Reply #6 on:** June 04, 2010, 01:52:13 PM »

Paul,
My pal ( dreaded RC kinda guy,, who rights for RC sport flyer) says that one version of the TP batteries, I beleive the generation prior to the newest one, had problems. His comments were to the point that they would not stay balanced. He said his were a constant source of frustration since it required more TLC and attention due to this. He finally gave up on them. However he states the new generation ( the ones listed as being able to charge at 5C) appear to be much better. Hyperion is making a similar pack now at a slightly lower price. Rob seems to think they are a good value as well. More to follow as it becomes available.
BTW, my new electric is almost done with design,,

as an aside, Rob has now completed two Control line planes, I gave him a spin on my Ukey last year and he was totally taken by it. Both his new planes are of course electric powered!

bob branch · « **Reply #7 on:** June 04, 2010, 02:00:37 PM »

Paul

None more than 20.

bob branch

Kim Doherty · « **Reply #8 on:** June 04, 2010, 02:16:25 PM »

Bob,

That is unfortunate.

Could you please provide some more info:

- How many packs did you have
- Were they new when you purchased them
- Which cells (i.e. version were they)
- Did you ever draw the pack below 3.3v/cell
- What was the failure mode
- Which charger / balancer did you use
- Did you always balance charge
- What "C" rating did you charge at
- Did you condidtion the packs prior to use
- Did you contact Thunder Power to discuss this issue

Inqiring minds want to know

Kim.

bob branch · « **Reply #9 on:** June 04, 2010, 04:15:39 PM »

Kim

A have to offer my aplogies to you and Thunder Power. The packs were in fact Poyquest PQ-4000SP-4S packs an not Thunder POwer. I had purchased some Thunder Powers of different size back at the same time which are no longer used (not stunt application) but not due to any failure mode. I had four packs, the other flier I believe 3. His were also Polyquests same models. I guess I mentally lumped them together in my head (happens when you get older it seems

). At any rate the packs were always balance charged on a cellpro 4 charger. One pack was overdischarged one time so I can excuse it. However, it is indistinquishable from the others. They were no longer able to provide adequate charge for a pattern in a smoothie with an axi 2826/12. They were retired to sport rc packs and preformed adequately til this year. They no longer provide more than a 2 minute flight and are now retired.

Again my sincerest apologies to Thunder Power. I hope that I made it at least clear I was not talking about current pacs.

bob branch

TDM · « **Reply #10 on:** June 04, 2010, 09:08:51 PM »

Quote from: John Witt on June 04, 2010, 11:11:53 AM

Thunder Power 5S 2600 20C = 284 g (10 Oz) @ $105 each (Internet source, don't remember who)

Zippy 2650 5S 40C from Hobby King = 458 g (16 Oz) @ $40 each

Zippy 3000 5S 20C = 439 g (15.5 Oz) @ $25 each

Note capacity and discharge rate differences.

John W

For my purposes I think I will end up with a 6S 2200mah or a 5S 3000mah or a 4S 3300 all depends on the KV of the motor.
Here are some comparisons.
6S For TGY 42-50 650
TGY2200 30C 369gr 30$
TP2200 340gr 149$
5S
TP3300 20C 392gr 130$
TGY3000 20C 414gr 27$
Z3000 20C 379gr 25$
4S Possible for a Trust40 motor
TP3300 4SPL2 20C 315gr 99$
TGY3300 4S 20C 358gr 35$
PQ3350 4S 351gr 68$

Probably my first option wil be
Trust40 motor and TP3300 4SPL2 20C 315gr 99$

Dennis Adamisin · « **Reply #11 on:** June 05, 2010, 05:09:31 AM »

Traian
Can you elaborate - I do not recall seeing the "Trust 40" motor shown before?

As you pointed out you can use either a 4S 5S or 6S power system successfully if you get a good match of kV to cell count. I have found that in high power demand systems like 6S those extra cells really drive down the current required - and current is heat. The flip side is that it starts limiting your choices some.

As Kim D points out energy density comes in to play, and 2200 cells seem to be a real sweet spot for mazimizing this paramenter. Thus the 6Sx2200 is a heck of a choice.

TDM · « **Reply #12 on:** June 05, 2010, 09:08:26 AM »

http://thrustmotors.com/
Look at the 40 it has perfect KV and it swings a 14in prop.

Motor specs
Outside Diameter 37.2mm
Length 41mm
Weight (gr/oz) 140gr / 4.9oz
Motor Shaft Dia. 5.0mm
Mounting Bolts Dia. M3
Max efficiency Current A * 35 A
Peak current A (15 sec)* 45 A
Battery pack range ** 2~4 LiPo / 6-12 NiCd
Poles 14
KV rpm/V 850kv
Recommended ESC PA Quantum 45
Peak Watts 500 watts

VOX 14X7 - Perfect match to the Thrust 40! Excellent higher range propeller for 3D, freestyle aerobatics
and pattern flying. Excellent balance of thrust and speed that allows a wider performance
envelope for aggressive flying such as insane tumbles, walls, hard snaps, spins and fast KE spins.
Double check the integrity of your plane’s motor box to ensure it can withstand the increased
loads. This is THE prop for the Ultimate AMR especially for low and slow 3D. Even though it is
much larger prop than the APC 13x6.5E it draws lower amps and produces a whopping 90.56oz of
thrust!! This clearly demonstrates the efficiency and advantage of the VOX over the APC.
Adequate airflow to cool down the motor and ESC is mandatory, as well as strict throttle
management.

Thrust® cooling design took a complete departure in the current thinking by engineering a
High Velocity Force Cool Ventilation (HVFCV) into the rotor end bell as well as taking full advantage of
thermodynamic properties of the stock material itself. HVFCV is achieved through a set of solid metal turbine
impeller blades painstakingly CNC milled as an integral part of the rotor end bell assembly, which not only provides
the positive force cool ventilation by drawing fresh cool air through the stator and magnets, but also doubles up as a
heat pump to first draw excess heat from the rotor assembly itself and then act as a heat exchanger by expelling it
through the air stream contacting the solid metal turbine blades as it spins at high velocity. Micro ridges,
intentionally CNC cut into the rotor, further multiples the end bell’s surface area and serve as radiators to further
boost thermal dissipation achieving unparallel cooling and henceforth having the ability to swing larger propellers
than other conventional outrunner motors of similar class while remaining considerably cooler and more efficient.
There is more to the “Cool” look of the CNC exterior casing than meets the eye, and looks can be deceiving. Under
the hood, is where serious engineering comes into play. With only the highest quality materials and components
used in the manufacture, the new PA Thrust® motors are manufactured with the tightest tolerance making it
possible to maintain the smallest air gap between the stator and shaped neodymium magnets, significantly boosting
torque and thrust. The relatively silent and vibration-free operation of the motor is a testament to the tight
tolerance manufacturing regime we have adopted specifically to harness the maximum power produced by the
motor (within the limits of today’s technology) for the sole purpose of swinging the prop. This allows the motor t
Copyrights ©2007 Precision Aerobatics. All rights reserved
swing propellers of at least one size larger than any contemporary motors in its class while running cool with
maximum efficiency.

Dennis Adamisin · « **Reply #13 on:** June 05, 2010, 11:56:11 PM »

Traian:

THANKS for the Thrust 40 motor info. From reading the specs it looks like a good motor, expecially with the integrated cooling fan. I would however ADVISE CAUTION on the recommended prop size.

I am prone to using motors conservatively (learned the smoky way) but I think the Thrust 40 is roughly the same external size and same weight (4.9 versus 5.0 oz) as the Turnigy SK 35-42 that I use in the Mythbuster. This motor is perfectly happy turning an 11x5.5, I think it would probably do OK turning a 12" prop under the right conditions but NO WAY would I ever think it would handle a 14" prop. Reading the "fine print" on the text you posted, I waw the phrase "throttle management" which I think means they do not intend for the motor to run at load for any duration.

Thus I hope your intended airframe will fly with the 11" prop, if not then I think you better plan on a larger motor & battery for a 13" or 14" prop. Here comes a shameless plug. I like the Arrowind 3526 with a 6S pack - the power system Brodak sells for the Strega-size applications For 4S Brodak has the Arrowind 2832 which is at least 12mm longr in the windings and magnets making for a LOT of power.

TDM · « **Reply #14 on:** June 07, 2010, 06:35:38 AM »

Thanks Dennis

I would like to be in the range of 12-13in prop. 13.5 to 14in prop is even better.
Back to the subject of batteries how would one justify 100$ for saving one ounce of weight?
Do some batteries last longer and it would justify the extra cost. I see if they last twice as long and give me the weight savings it would justify it but if I have to add nose weight to balance the plane all I do is unbalance the checkbook. Of course u can move the pack in the airframe to get the balance point right. Still they look awfully expensive.
How many cycles can you run on a typical battery? Our gage is the equivalent cost of fuel or $ per flight as well as reliability.
Speaking of reworking motors I already have in place a new spinner design for the Revolutions as well as core motor cooling that will cool your brains off when you see it

. So I will steal the Thrust motor idea and implement it on the motor of my choice to get the most from it.

Larry Wong · « **Reply #15 on:** June 07, 2010, 07:01:56 AM »

Paul congratulation to you and Eric, What is your set up on this plane that you can use a 2600 battery, as I recall the first plane used about 3000 on each flight?

TDM · « **Reply #16 on:** June 07, 2010, 07:19:07 AM »

More yet does anyone has some logs on batteries on how many cycles do they last. Lets see if we can have a trend here maybe we can do like a POST YOUR SETUP type thread and we can see what battery, how many cycles, any failures, fires and whatever else you may think to add on.

Kim Doherty · « **Reply #17 on:** June 07, 2010, 09:23:21 AM »

Quote from: Larry Wong on June 07, 2010, 07:01:56 AM

Paul congratulation to you and Eric, What is your set up on this plane that you can use a 2600 battery, as I recall the first plane used about 3000 on each flight?

Larry,

That's a great question. To understand how Paul has arrived at the current setup I thought it would be helpful to understand how the first setup came into being. Early in 2005 when I made the decision to fly an electric model at the 2006 W/C's in Spain I was literally starting from less than zero. I lived in a world of tuned pipe PA motors, 18% oil, 15% nitro etc. I needed to broaden my base of knowledge so I could begin to structure a project plan to ensure that I would have a model ready in time. My first thought was to contact a friend of mine who is the Committee Chairman for F3A (R/C Precision Aerobatics) and get his input since the team members were flying large electric powered models. This fleshed out some basic parameters and he offered to introduce me to Chad Northeast a team member, fully sponsored FUTABA team pilot and Thunder Power sponsored pilot. Chad is an electrical engineer and went over every parameter that was relevant with me. It should be noted at this point that Chad had felt that smaller systems might also work but my criteria was pretty stringent. The system had to be able to hover a model larger than my intended design (as if you had full throttle control) and accelerate vertically out of that hover. To understand why I was not sold on the "lower power" systems remember that I WAS going to the W/C's and I WAS going to compete with a viable electric model. Nothing less than "competitive" was the goal and everything in the package had to support this. Arriving at the W/C's with an underpowered, uncompetitive model was not an option so we were going to have POWER!! So far this had not been done before at this level or with a model of this size.

The original weight budget came from Paul's assertion that a 63 ounce IMPACT was a good weight on that wing area. Add six ounces of fuel and we were at an all up weight of 70 ounces. I estimated that I could build a 740 square inch model complete without power train at 38 ounces. This left 32 ounces for the entire power train. Then working backwards we evaluated literally dozens of possible motor/battery/esc combinations. After much debate the original setup of Plettenberg Orbit 30-12, Schulze 18.46K ESC (not 18.46K F2B ESC) and Thunder Power 5S2P 4200 battery packs was settled on.

After flying the setup for a while it seemed that a draw of approx 2700 mA / flight was the norm. The W/C's came and went, the model "SHOCKWAVE" was a success in every way. Not long after I returned Paul contacted me and thus spawned the first of his electric models with the original setup. Now to optimize the system and the available potential energy from the battery we began to experiment with different props, diameters, pitches, undercambers, line lengths etc. We were able to get the system to draw approx 3000 mA's.

At this point Paul was seized by a demon that compelled him to build and develop at an inhuman rate that I could only watch. I will let Paul continue the story from here...

Kim.

Richard Lewis · « **Reply #18 on:** June 07, 2010, 09:26:44 AM »

Here is a link to a site maintained by a prominent figure in the F3A (FAI R/C Pattern) world. He has gotten lots of setups posted and solicits data on battery packs and their use/lifespan from R/C pattern guys worldwide. Lots of good info here on really high performance electric setups.

http://www.electric-f3a.com/

Richard

TDM · « **Reply #19 on:** June 07, 2010, 01:24:52 PM »

Quote from: Richard Lewis on June 07, 2010, 09:26:44 AM

Here is a link to a site maintained by a prominent figure in the F3A (FAI R/C Pattern) world. He has gotten lots of setups posted and solicits data on battery packs and their use/lifespan from R/C pattern guys worldwide. Lots of good info here on really high performance electric setups.

http://www.electric-f3a.com/

Richard

Thanks Richard
I looked at the data in that site it is somewhat summary. I still can not have a clear picture as of what battery performs consistently. From that site i saw that the best battery is the thunder power and it only lasts about 150 cycles before it becomes uncompetitive. The rest of the data is not substantial. I did not see tests on batteryes that brings them down and specifies for example battery a lasted X cycles and Battery B lasted Y cycles etc.

Howard Rush · « **Reply #20 on:** June 07, 2010, 03:04:50 PM »

I haven't looked into this too deeply, because I don't have an electric plane yet, but I'd think the parameters of interest would be battery weight and energy available per flight for long-term operation.

Kim Doherty · « **Reply #21 on:** June 07, 2010, 03:07:30 PM »

Quote from: Traian Dorin Morosanu on June 07, 2010, 01:24:52 PM

Thanks Richard
I looked at the data in that site it is somewhat summary. I still can not have a clear picture as of what battery performs consistently. From that site i saw that the best battery is the thunder power and it only lasts about 150 cycles before it becomes uncompetitive. The rest of the data is not substantial. I did not see tests on batteryes that brings them down and specifies for example battery a lasted X cycles and Battery B lasted Y cycles etc.

Dorin,

150 cycles in competitive use is good battery life. When I started using electric power everyone was talking about batteries lasting for 300 cycles or more. Well they will last for 300 cycles but they begin to degrade around 150 cycles or so. It is important to consider that any top F3A pilot is either partially or fully sponsored for their batteries and that skews the results of this type of information since they will have no issue with pulling out a new battery if an older one is even slightly off. I still have eight of my original 5S2P 4200 Thunder Power packs from 2006 and use them in my helicopter. (I run 5S4P 8400) As Paul said, at $100.00 / battery and at least 100 cycles / battery this is the same cost as fuel for an IC engine. Battery life is a gamble which can be moderated with careful attention to handling the batteries. I have had batteries last 1 day, 2 months and 4 years. In each case I did something that directly influenced the life of the battery. For as many "Brands" of batteries that are on the market they are made by a relatively few number of companies. If you take a broad based look at top level F3A you will see three names more than all the rest: Plettenberg Motors, Schulze ESC's and Thunder Power Batteries. If these were not the best available these pilots would not use them since they could get a sponsorship from any manufacturer they wish. As to weight saving vs cost I would say that yes for a competitive setup the extra dollars are worth it. Be aware that less expensive batteries are generally larger in dimension and not offered in as many usable form factors. Uncle Dennis would have you purchase your entire system from the change you get back from a twenty after buying a 20 piece bucket of Kentucky Fried while Paul will cause Ali Velshi to consider his purchases from a Macro Economic impact viewpoint. Neither better for each others chosen purpose. Each is what is required. For most of this equipment you get what you pay for.

Kim.

Howard Rush · « **Reply #22 on:** June 07, 2010, 03:22:20 PM »

I learned from Nelson engines that money can buy happiness.

Kim Doherty · « **Reply #23 on:** June 07, 2010, 03:50:55 PM »

Quote from: Howard Rush on June 07, 2010, 03:22:20 PM

I learned from Nelson engines that money can buy happiness.

Back in the eighties I (and Wayne Petrevan) set a Canadian Scale Goodyear racing record with a Nelson .15 We fired first flip. The rest is history. Very satisfying day! I have also been to the temple mount in Zelienople and flown on Henry's TR circle. Henry makes good stuff

Richard Lewis · « **Reply #24 on:** June 07, 2010, 06:29:18 PM »

Quote from: Kim Doherty on June 07, 2010, 03:07:30 PM

Dorin,

150 cycles in competitive use is good battery life. When I started using electric power everyone was talking about batteries lasting for 300 cycles or more. Well they will last for 300 cycles but they begin to degrade around 150 cycles or so. It is important to consider that any top F3A pilot is either partially or fully sponsored for their batteries and that skews the results of this type of information

While I agree with your point that these guys will fly what gets them the perfromance they require, absolutely they do, and the Hacker C50 geared inrunner seems to be on top right now, with a handful of outrunners (Plettenburg, Neu) giving them a run for their money....

I have to disagree with the skewed results due to sponsorship...I know some of the top level guys and am familiar with many more, and very few of them have the type of "sponsorship" that you may think. Sure, they do get deals on some things, but not the kind of full ride sponsorship that you may think....Anyway, I did not mean to start a war of words, just provided a link to a site where some of the guys that are out there on the cutting edge of pushing electrics to their absolute limits in weight to performance ratio...

Richard

Kim Doherty · « **Reply #25 on:** June 07, 2010, 08:40:55 PM »

Quote from: Richard Lewis on June 07, 2010, 06:29:18 PM

While I agree with your point that these guys will fly what gets them the perfromance they require, absolutely they do, and the Hacker C50 geared inrunner seems to be on top right now, with a handful of outrunners (Plettenburg, Neu) giving them a run for their money....

I have to disagree with the skewed results due to sponsorship...I know some of the top level guys and am familiar with many more, and very few of them have the type of "sponsorship" that you may think. Sure, they do get deals on some things, but not the kind of full ride sponsorship that you may think....Anyway, I did not mean to start a war of words, just provided a link to a site where some of the guys that are out there on the cutting edge of pushing electrics to their absolute limits in weight to performance ratio...

Richard

Richard,

I have some familiarity with the sponsorship thing and not having to use tired batteries. I did not see a "war of words" starting and was not trying to promote anything that has not won it's fame fair and square. Hackers are good motors. Plettenbergs and Schulzes were good enough for Paysant Leroux and some entire F3A teams. Cutting edge eh, pitty.

Kim Doherty
Thunder Power Sponsored Pilot

Paul Walker · « **Reply #26 on:** June 08, 2010, 01:54:12 PM »

[At this point Paul was seized by a demon that compelled him to build and develop at an inhuman rate that I could only watch. I will let Paul continue the story from here...

Well, I wouldn't consider one quality plane a year an "inhuman" rate. !!

Taking Kim's set-up, I started to see what I could squeeze out of it. I tried various props that "fit" the KV of the motor I had, and used the torque available. I set about to develop a new design that would easily carry the weight of the original system. It was a one piece plane to minimize weight, and it ended up at 750 square inches and weighed 69 ounces. I used it at the Nats and Team Trials. It was one of my poorer finishes at the Nats (4th I believe), so I tend to forget that part. It did qualify me for the US team for the 2008 WC's. It nearly won that competition.

I then made the same design ,now in a take apart configuration. It weighed 75 ounces but was "prettier" for the WC's. It as well flew good, and I was headed to the WC's with my first electric. However, there was a bird with my name on it that said NO. The next season I was determined to improve the looks and weight, and set about on a new design. It was only cosmetic though. The plane was fashioned after the All American Eagle. However, again, being a full take apart it weighed in at 75 ounces once again. It flew fine, and did reasonably well. I also experimented with the smaller and lighter 4000 packs. They were adequate as I was taking ~3000 mah out per flight.

By now, I KNEW there was more performance to be had, and the only way I was going to get it was to get the weight out. That I did. The new design was reduced from 750 to 650 square inches, while maintaining the same length fuselage. I fooled the eyes by moving the vertical tail forward, and making a bit smaller. The nose was also lengthened as a by product of a lighter motor. I have also experimented with the 2600 Thunder Power packs that weigh in at just over 10 ounces. With that pack, the new plane weighs in at 58 ounces! With the heavier 4000 packs, it is 62 ounces. Wow, what a difference in performance. I am using the same "basic" power system that was used all along. The smaller motor will still carry the same prop as the biggest motor I used and I can't feel the difference in power at the handle. So I have the power system that can pull the 75 ounce plane easily in a 58 to 62 ounce plane. The new plane turns and locks like no other plane I have flown (very similar to Arden Zangs Skywriter that I flew in '92 in Vancouver). It presents very well, and all who have seen it seem to agree.

I also reduced the thickness of the wing. That combined with the size reduction, resulted in less energy needed to fly it. That's why the 2600 pack will work in this plane. I only use about 2100 per flight now! The other change I have made is to the prop. This plane now uses the APC 13*4.5 pusher prop. It works very well, and I have not found another that is better for this plane! Some day, I will try that prop on the 75 ounce plane!

The next project might be to make the wing thinner once again to further minimize the required energy. The thinner wing certainly makes the overheads in the wind easier! I will also make it a take apart plane, in case I am invited to the 2012 World Champs!

I am satisfied with the changes made to date. I think that it will only get better in future designs.

Paul Walker
Not TP sponsored

William DeMauro · « **Reply #27 on:** June 08, 2010, 06:45:08 PM »

Hi Paul,
"The smaller motor will still carry the same prop as the biggest motor"
I've started watching power system,prop, battery combinations closely as I start preliminary planning for a replacement plane for my SV-11. I feel that I can do much better now that I understand this whole thing way better. My biggest goal is to improve the efficiency of my system as my numbers pretty much match yours, until now, and most others. Therefore may I ask exactly what smaller motor are you using? Thanks in advance!!!
William De Mauro
(totally unsponsored)

Dennis Adamisin · « **Reply #28 on:** June 08, 2010, 08:40:19 PM »

Very good synopsis Paul - thank you for sharing that. I am certainly on-board with thin wings and weight reduction - tho that latter has always been my downfall!

...and as Bob Hunt likes to say, "its only getting better!"

Roger Anderson · « **Reply #29 on:** June 09, 2010, 07:20:53 AM »

Thanks to Paul Walker for his last post. All of us guys out here have been trying to figure out why we are using so much more power for our flights. All of our planes weigh in the 68 to 76 oz range and we all use from about 2400 mah to 3000 mah for a 5-1/2 minute flight. There is no way with our current airplanes and equipment that we could get away with a little 2600 mah battery. Now we see that Paul also used in the 3000 mah range for his earlier experiences with electric and this shows we still have a way to go on our electric control line learning curve. I do know this though, we are having a very good time with our electric stunters. That boring consistancy is just great!

Roger Anderson

Dean Pappas · « **Reply #30 on:** June 09, 2010, 08:42:26 AM »

Hi Roger,
Are you using 4S or 5S packs?
Dean P.

Roger Anderson · « **Reply #31 on:** June 09, 2010, 08:37:00 PM »

Hey Dean,

We are using 5S packs. We tried 4S packs on four of the five electric aircraft that we have operating and found that they all have some drop off toward the end of the flight. The planes still performed OK but lap times did slow down at the end of each flight. There is no slow down when we use 5S packs. Most of us are now using 4000 mah 5S packs and they perform very well.

Howard Rush · « **Reply #32 on:** June 10, 2010, 12:08:24 AM »

It will be interesting to put some instrumentation on these airplanes to see where the power is going.

TDM · « **Reply #33 on:** June 10, 2010, 06:05:56 AM »

Quote from: William DeMauro on June 08, 2010, 06:45:08 PM

Hi Paul,
"The smaller motor will still carry the same prop as the biggest motor"
Therefore may I ask exactly what smaller motor are you using? Thanks in advance!!!
William De Mauro
(totally unsponsored)

And the question has not been answered yet. I am sure may of us want to know the answer to this question. Paul if you please can you post your current set up on your current plane.

Dean Pappas · « **Reply #34 on:** June 10, 2010, 07:01:28 AM »

Hi Gang,
Roger, the reason I asked about cell count is to do a quick calculation. The typical weight-specific energy consumption (sounds so fancy doesn't it?) to fly a schedule has been about 0.7 Watt-hours per ounce of RTF weight. This figure is for 67 foot lines and is adjusted roughly proportional with line length. Taking the range of figures you gave above I get a range of numbers that average the same, so your energy consumption isn't high. Now, Dennis A. has been using only about 90% of that figure since the git-go, and with his developments Paul is working to meet him ...

The bugaboo is the sag at the end of the pattern. Efficiency and battery consumption improve with RPM that is a higher percentage of the battery voltage times Kv, BUT there is a price. You need enough voltage overhead for the moment just before the push before the 3rd loop in the clover. You mentioned that with a 4S/4000 mAh battery you got a drop-off in power. Well, 75% or 80% of the capacity of a 4S/4000 battery is enough to fly a plane in the very low 60 ounce neighborhood, not one near or above 70. With maybe an additoinal 1/2" of pitch and lower RPM you could have avoided that droop, but at the expense of abusing the batteries.

Howard, the data is there: go look for some of the threads where folks have used the EagleTree data logger to monitor battery current at the max sampling rate of 1/10 second for the entire schedule, and start analyzing! You can see the airplane accelerate and decellerate transitioning from upwind to downwind and back in level flight in the wind, and you can estimate how much energy it takes to climb to the top of the circle and how much you don't get back in the corresponding dive ... The Castle ICE loggers are good too, but I don't remember seeing data at similar sample rates.

later ...
Dean P.

Jason Greer · « **Reply #35 on:** June 10, 2010, 08:10:16 AM »

Dean,

This is one of my earlier log files from my castle ice 50. The sample frequency is 10 hz.

My power system consists of:
motor: Scorpion 3020 890
esc: ice 50
prop: 12x6 tractor
battery: 4s 2600 TP prolite V2
timer: Hubin fm-2a
flight time: 5:45
power consumption: 1900-2000 mah
lines: 64' x .015

The ready to fly weight of my model is 45 ounces. I have not kept a very good log of the number of flights per battery, but I feel confident that I have over 100 flights per battery and I have seen no degradation of performance from any of my Prolite V2 packs.

Thanks,
Jason

Dean Pappas · « **Reply #36 on:** June 10, 2010, 12:19:57 PM »

Thanks Jason

Dean

Mike Ferguson · « **Reply #37 on:** June 11, 2010, 10:21:05 AM »

Quote from: Paul Walker on June 08, 2010, 01:54:12 PM

I also reduced the thickness of the wing. That combined with the size reduction, resulted in less energy needed to fly it. That's why the 2600 pack will work in this plane. I only use about 2100 per flight now! The other change I have made is to the prop. This plane now uses the APC 13*4.5 pusher prop. It works very well, and I have not found another that is better for this plane! Some day, I will try that prop on the 75 ounce plane!

That's interesting. What did the wing thickness for the new plane wind up being?

John Witt · « **Reply #38 on:** June 14, 2010, 10:04:45 AM »

Interesting. My vector 40 is also using ~2100 mAh per flight with (I think) a few laps less than Paul's flights. I am using the same prop cut down to 11.7 inch diameter. 4S pack vs. Paul's 5S pack. My stuff is all cheapo Hobby King as well.

Paul, of course, flies a great deal better than I

and I wonder how much of the extra energy is from my more erratic control movements. One of the fascinating things about e-flight is the ability to see how much energy a particular flight uses.

John W

Paul Walker · « **Reply #39 on:** June 14, 2010, 12:49:22 PM »

Quote from: Mike Ferguson on June 11, 2010, 10:21:05 AM

That's interesting. What did the wing thickness for the new plane wind up being?

The new wing thickness is approximately 2.25 inches. That's down from over 2.5 inches thick.

The motor on the new plane is the Plettenberg Orbit, 20-16. It uses the APC 13 * 4.5 pusher prop. 5S battery packs.
I'm still using the 4000's now as the plane flies soooo good I hate to change things. I have flown with the 2600's, and it is nearly 4 ounces lighter, but will require some trim changes. Time will tell if 4 ounces lighter is the way to go on this plane. I hope so!

Paul

William DeMauro · « **Reply #40 on:** June 14, 2010, 05:59:22 PM »

Thanks Paul!!