RunRyder - Swift 620 600A motor and 8S lipo, can it be done??

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e-Century Hummingbird - Swift > Swift 620 600A motor and 8S lipo, can it be done??

hcuellart
Heliman
Location: South Padre Island, TX

Hi guys I read somewhere that the 600A motor can handle an 8S lipo with an HV ESC and an adequate pinion. Can this be done? Can someone guide me where I could get such a pinion if this was possible? I know Century will not have one...
Or should I just buy the 650 and HV century ESC? As I got a good deal on this heli with the 6S power system but would like to have mine on 2 X 4S packs...
Regards,
Homero

03-17-2008 01:35 AM

MMike
Key Veteran
Location: Holland,Mi-USA

Swift High Volts

The host on "All things that fly" podcast has a custom Swift with high voltage.

He talked about it on ATTF 18.

Proud member of the E-SKY INCROWD!!!!

03-17-2008 01:52 AM

HOMEPAGE

laughingstill
Key Veteran
Location: Gainesville, Fl, USA

Just go with the 650 and the appropriate ESC, it will last longer and work better....Ron

3DMP-E, Logo 6003D, Logo103D Carbon and Trex 450se Flyin Firefighter

03-17-2008 03:12 AM

Ravenhyper50
Senior Heliman
Location: Ottawa

Quote
Swift 620 600A motor and 8S lipo, can it be done??

EDIT: My test is done with A123 lower voltage cells Not LIPO
sorry had A123's on the mind

With my experience yes it can be done(with A123's). I have tried 8 & 9 cell A123 with the 80/100 electron ESC and the 600+ with the 8 & 9 tooth pinion with over 100 flights with the 9 tooth 9 cell A123 and over 20 or so flights with the 8 tooth and 8 cell A123 no problems with the power system as of yet! ....I did not even think it would last this long

Thought I would need a new esc and motor by now(due to over volts/rpm of recommended specs) but it just keeps on going

.....Wanted to post this sooner but did no want to give misleading information till enough testing was done

on the A123 cells

MSH Protos 500, SWIFT 550 Carbon, Swift 620SE, DX-7, JR servos

03-27-2008 10:42 PM

oldfart
Elite Veteran
Location: Vancouver, Canada

Ravenhyper50 & hcuellert

There is a BIG difference in voltage output under the type of high load application that our helis present to a battery pack between that from an 8 cell A123 pack and and that from a 20C or better 8S Lipo.

The nominal voltage of the A123 is only 3.3V while under our loads it drops to only 2.75V or so. Consequently while flying it will only deliver 2.7V x 8 = 22.0V in total a 2300 mah

On the other hand a 20C or 25C lipo cell has a nominal voltage of 3.7V and under our loading only drops to 3.6V, and some even stay at 3.7V under such heavy loading! Consequently a 6S/2300/20C Lipo will deliver about the same as an 8 cell A123 (3.6 x 6 = 21.6V or 22.2V with the better ones)

An 8S lipo (as in the initial question) would deliver a lot higher 3.6 x 8 = 28.8V

As the 600A is rated for a max voltage of 22.2V it will run very happily and very well with either the 6 cell Lipo or the 8 cell A123. But it will not do well with the 28.8V of the 8 cell Lipo.

Also to consider is that with the lowest pinion size that will stand up to that power (9T) your rotor speed would be ballistic as the 600A is a motor with an1110 KV rating (rpm/watt).

Calculating for rotor speed, the 21.6 Volt would mean a motor speed of
23976 rpm. Using the 9T and considering the maingear has 96T, the resultant gear ratio is 10.67/1 (96/9). So at 100% efficiency the rotor speed would be 23976/10.67 = 2241. Now factor in an 85% efficiency estimate and you would have a rotor speed of 2241 x .85 = 1904.

Doing the same math with the 8S lipo you would get a rotor speed of about 2550!!!! That is why you must go to the 650 series with the 8S Lipo. They are designed for higher voltages and lower KV's.

03-27-2008 11:58 PM

Ravenhyper50
Senior Heliman
Location: Ottawa

Hey OldFart, do you think I would be safe @ 9 cell A123.... @ 9 cell with the 600+ and the 80/100esc. I think I was over the spec a little. I was running the 9 tooth pinion ....it was a rocket but did not like the short flight times

Now running 8S A123 with the 8 tooth pinion from Century with 100% straight curve it sounds normal now

I question if this machine can lift a 12 of beer

with my set up now

MSH Protos 500, SWIFT 550 Carbon, Swift 620SE, DX-7, JR servos

03-28-2008 01:35 AM

centuryman
Veteran
Location: deerriver,mn usa

I just talked to helli world on the sams subject. the said the old 600 lighting's ran great on 8s but the new 600 a plus will burn out on 8s. I also tryed 8s 123's no problem. and a swift is an abslute rocket with a pair of 3s 2170 at 2500 headspeed wheighs 5 pounds even can pull 14.5 pitch, flips and rolls so fast it's allmost a blur.you would have to run an 8 tooth pinion to run 8s and think you would strip maingears with that much power and that little gear engagement. however if you could fit the 620 double gear that would solve that but they don't make an 8 tooth long pinion.

03-28-2008 03:15 AM

oldfart
Elite Veteran
Location: Vancouver, Canada

RH50,

The keys to any question like yours is the KV rating of the motor, the Voltage under load of battery pack, the Mah rating of the battery pack and the C rating of a battery pack, and the gear ratio one is using.

I will compare a proven $240.00 Flite Power, Electrifly, or Thunder Power 6 cell 5000/20C battery pack to a 9 cell A123 pack that is claimed to be 30C.

The 6S1P lipo will deliver 3.6 x 5 = 21.6 volts under load. Running it down to 85% means it will give that voltage through 5000 x .85 = 4250 mah. Now considering the 20C rating (amp delivery rating), they can work at up to a 5.0 (5000 mah)x 20 = 100 amp draw. So max safe wattage (power) capability would be 21.6V x 100A = 2160 watts. As 746 watts is considered 1 hp, that means with the proper motor, ESC it can deliver 2160/746 = 2.9hp!!!

The much heavier 9S A123 will deliver 2.75 x 7 = 24.75 volts under the same load. They are rated at 2300 mah and drop off fast after 85%. Consequently their useful mah is only 2300 x .85 = 1840. The A123's 30C rating would yield a 2.3 (2300 mah) x 30 = 69 amp draw. So they can deliver 24.75V x 69A = 1707 watts (2.29hp). Unfortunately, as they are only 2300 mah they will only be able to do so for 46% as long as the 5000 mah 6S1P Lipo.

So if I get a 6 minute "YEEHAW" flight with my 6S1P lipo, using a gearing that turns the rotor at 2150, then I will only get less then a 3 minute flight with the much heavier 9S A123.

Can 2.29 hp capability of the 9 cell A123 pack lift a 6.6 pound Swift plus a 12 pack of beer - I would think it can, Just as a 250 hp motor can power a car or a big truck - it will all depend on how you gear it.

Centuryman

The reason the older 600 could take the higher voltage better, was because it was an 800KV motor rather then the 1110 KV of the newer 600A. This means it would not give the same rotor speed or use the same wattage when paired with the same pinions to battery pack combinations. But if you changed pinions on the older one to yield the same higher rotor speeds, using the same battery packs, the older one would burn out very quickly.

03-28-2008 06:00 PM

Ravenhyper50
Senior Heliman
Location: Ottawa

Wow thank you oldfart for showing how to do the REAL math for A123 packs. I have learned something new from your posts.

For me I had to find out through trial and error on how the swift would perform with the A123's ....your calculations were bang on! With the 9 cell A123 pack with the 600mm mains and 95mm tail I am getting 3 mins of anything I can throw at it

I can get 3:25 but any longer and its auto time!!! so I set my timer for 3 min and I'm ok with that for now. Not excited about the flight times but the 15-18 min charge times kind of make up for it

and I don't wait for packs to cool or worry about fire or taking the pack off the machine.
I just fly, land, charge, fly again soon as my charger beeps

In time I will definitely switch back to lipo for true power and weight savings, but for now 299.99 for a good 5000mah 6s lipo is just to much to crash right now

...I am always pushing myself! so it happens a lot. Real life flight is my SIM!
( I have a sim it just does not compare

)

Ten A123 cells @ my door for less than $100
Main reason I gave them a try

MSH Protos 500, SWIFT 550 Carbon, Swift 620SE, DX-7, JR servos

03-28-2008 07:05 PM

bellecrank
Veteran
Location: Canada

Another interesting calculation that many do not make, is charge time, to flight time per hour.

With a good balancing charge system like the TP system, one can comfortably recharge a 6S lipo in 35 - 40 minutes.

So if you use 17 minutes to recharge and get a 3 minute flight (total of 20 minutes), a ratio of 3/20 x 60 = 9 minute of flight per hour

With the TP system, one would get 6 minutes per 38 minute of charge (44 minutes) for a ratio of 6/44 x 60 = 8.18 minutes of flight per hour at the field.

Personally, I would find a 3 minute flight too short, as it would seem that just as I was starting to have fun or get something burned into my brain, I would have to land and recharge or change batteries.

If you are happy with a 3 minute flight, you could use a good 3700 mah 4S/25C lipo, gear for the same head speed, and get a much better power to weight ratio.

What I like about electrics, and the versatility of the Swift helis, is that there are so many ways to skin the cat.

For under $500.00 (including motor, ESC and 4S battery pack) one can have a great long running, mild mannered 5 lb. trainer, scaler or sport aerobatic model or go all out for $700.00 or so, and have a YEEHAW 3D animal or super lifter with EXTRA LONG endurance.

...and with upteen possibilities in between.

03-29-2008 04:23 AM

centuryman
Veteran
Location: deerriver,mn usa

Hey thanks for the info OLDFART. I HAVE BEEN EXPERIMENTING WITH A123 PACKS AS WELL. Like you said they just don't deliver the power. i'm going to convert one of my hawks to eletric for my girlfreind to learn to fly on and use them in that. i won't be waisteing anymore money on more a123 packs once these are done it'll be lipos .as for the 600 motor joe at helliworld couldn,t tell me witch motor i have ,but from the sounds of the 800 kv rateing i have the new A MOTOR cause i'm getting 2200 hs on a 9 toth pinion and 2450 on a ten tooth pinion . I'd only be running 1400 to 1700 on an 800 kv motor.i want to try a 1907h /2y motor it has a kv of 675 and on 8s and 13 pinion i should be in the ballpark. withe the fp3200packs they can pull 96 amps cont. and peak 192 and only weigh 24 oz. only 4 oz heavier then my 6s pack . should net me 4 hp over my current 2.2 hp and the bird weighs 5.5 pounds now so that would be 5.7 pounds to 4 hp a ratio of 1.425 pounds to hp instead of my current 2.5 pounds to hp. sounds like fun to me . what do you think? RH50 i put my battery in the canopy . it protects it in a crash . have wrecked a battery yet plus it balances better. youy may have to bring your front canopy pins up and forward a bit to get the room depending on battery size , then put the receive in the cavity underneith and the speed control and bec in the back between the frame and barrey plate. I also don't like the sim just not the same.

03-29-2008 12:22 PM

laughingstill
Key Veteran
Location: Gainesville, Fl, USA

Centuryman,
If you ran the Z30A 800kv motor, 10s A123, and a 9 tooth pinion, I promise you you will have all the power you will need. I had that setup and it rocked!!

3DMP-E, Logo 6003D, Logo103D Carbon and Trex 450se Flyin Firefighter

03-29-2008 12:31 PM

centuryman
Veteran
Location: deerriver,mn usa

I'm not familar with that motor . got some specs? I just whant the most power i can get and still keep it lite. I heard neu was the best for that , but i'm new to eletrics so all info you have to that regaurd would be aprriciated. run time not important, i usaully warm up on one of my 12 nitro choppers and save the serious fun for the eletric.so run time not important .after 4 minutes on this nervous little rocket i'm usually ready to land.

03-29-2008 12:48 PM

laughingstill
Key Veteran
Location: Gainesville, Fl, USA

That motor is the same as the 800KV Century motor.....Ron

3DMP-E, Logo 6003D, Logo103D Carbon and Trex 450se Flyin Firefighter

03-29-2008 12:52 PM

oldfart
Elite Veteran
Location: Vancouver, Canada

Yes, I certainly think A123 have their place, but for power per oz. LiPos cannot be beat.

The visual difference between the old 800KV 600 and the new 600 is that the old one had black/purple colors and the new 1110KV 600A's have a silver/purple coloration.

10 A123 will give a lot of power under load (27.5V)...about the same as a 7 cell lipo...and on an 800KV motor, geared for 2100/2200 head speed, they would perform very well....but not as well as a 7S/3700 cell Lipo - simply due to weight and the flight times would be a lot less.

Personally, If I wanted to power up with more then 22V (6 cell lipo) I would go with the new Century 650 motors (they come in two different KV ratings) and use their new CNE485 Hi-V ESC.

Why spend money experimenting when their flight team already have and have already narrowed it down to what works best and then offer it at very good prices?

03-29-2008 06:10 PM

centuryman
Veteran
Location: deerriver,mn usa

Thanks Old Fart for the response on the 600 motor because I was wondering if I could run 8S on that motor. I agree the 650 motor is a good motor but I have had bad luck with Century ESC's and for a little more money, I could have a Castle HV85.

03-29-2008 10:20 PM

oldfart
Elite Veteran
Location: Vancouver, Canada

The only time I had trouble with a Century ESC (and I must admit with two other brands also), was when I first got into large electric helis and would mistakenly set them up with improper throttle curves (mistakenly using my knowledge base gleaned from glow engine powered helis.)

An electric motor is relatively self governing compared to a nitro burner. It will only try to take from the battery pack, the wattage that is required to turn at its' most efficient rpm (which is directly related to its' KV rating). That is why, it is critical to select the proper pinion gear. One that will result in the gear ratio that will give you the head speed you want to fly at, while your motor will be turning at its most efficient rpm. That will be the motor rpm calculated by multiplying the Volts of your battery pack under load times the KV rating of the motor. At a 100% ESC setting, this is what will result.

Then you can have a throttle curve that is 100% across the top (the setting where the ESC works most efficiently) and your heli will maintain the same rotor speed no matter what load you set with collective and cyclic inputs. All that will happen is the motor will draw from the battery, the wattage it would need to maintain that motor speed.

The only time the rotor speed will change is when the load gets greater then what the motor is designed for - then your rotor speed will bog and your motor, ESC and battery will run hot.

That is why it is not recommended to have a throttle/ESC setting less then 70%. The 30% that is not used will be changed into heat within the ESC - heat is the killer of any electronic circuit. Personally, I never set any ESC for less then 80% anymore.

Another thing that can blow them, is if one uses the BEC circuit that are built into some, to step down too much voltage (e.g. from 22.2V to 4.8V). If the BEC circuit is not designed to do such a large step-down...remember the difference has to be dissipated in heat...good-bye ESC. This is why some ESC's will instruct you not to use their internal BEC when using more then 4 cells (as in some of the early Century ESC's). I blew one such 55A ESC from being a typical male and not completely reading the instructions.

I have also burned motors in the past, by not over loading them relative to their design specs, by using to big a rotor blade and/or too much pitch and /or the wrong pinion that ried to drive the rotor at too high a rotor speed.

Since learning these expensive lessons a number of years ago, I now read all the specs and instructions completely to insure I am buying batteries, motors and ESC's that are rated to put out the power (wattage) that would be required to do what I want done.

Also, now all my big electrics are set for a slow ramp up and a normal throttle curve of 0/80/90/100/100, so that on initial start up, I do not strip the maingears. And then I simply flip into idle up at 100 across the top for flight - regardless of the collective pitch curve or cyclic pitch settings that I have for that mode. Of course I set these so that they do not cause the motor to bog excessively.

03-29-2008 11:21 PM

Ravenhyper50
Senior Heliman
Location: Ottawa

Hmmmm, all this great info has got my wheels turning in my head

I was thinking... Would I be better off if I take the two extra A123 cells I have and make a 5 cell 2 parallel 4600mah A123 pack and gear up with a 13 or 14 tooth for good head speed?

Would this set up be better than my current 8 Cell 2300mah A123 OR my past 9 Cell A123 set up...????

Would I get better power with higher amp rating..?
would I get a longer flight times..?
What would the pros and cons between the two power options..?
Can someone show me how to work out all the numbers needed to compare the two( my math sucks

)
TIA

MSH Protos 500, SWIFT 550 Carbon, Swift 620SE, DX-7, JR servos

03-29-2008 11:31 PM

oldfart
Elite Veteran
Location: Vancouver, Canada

RH50

As a general rule, for attaining the same watts of power, it is more efficient (e.g. less heat generation etc.) to use higher volts and less amps. (Note that most stoves and the cloths dryers in our houses use specially wired 220V outlets instead of the standard 110V outlet).

I think one of the main reasons for lower cell count and higher amperage use here, is related to the cost of the higher cost of the HV type ESC's, of the chargers and their associated AC/DC power supplies that are required to charge higher cell counts in series. ESC's, power supplies and chargers that can do this efficiently are relatively expensive.

In the power area we are working with here, the difference is almost inconsequential, specially relative to the charger/power supply costs required.

03-30-2008 01:06 AM

Ravenhyper50
Senior Heliman
Location: Ottawa

So with 5s2p A123 the performance would be the same as 9s1p A123 Just the 5s2p would be less efficient ??....meaning the system would be running a little hotter?

MSH Protos 500, SWIFT 550 Carbon, Swift 620SE, DX-7, JR servos

03-30-2008 02:10 AM

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e-Century Hummingbird - Swift > Swift 620 600A motor and 8S lipo, can it be done??

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