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Old Oct 31, 2006, 12:24 PM
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Jurgen Heilig's Avatar
53859 Niederkassel, Germany
Joined Sep 2000
18,760 Posts
Quote:
Originally Posted by punkrockd
hey guys what would be your opinions on bl motors for a 2s setup?
Please take your time to go through the thread. There are plenty of options.

If I wanted to go brushless (which I don't with this model ), I would use two Castle Creations 18A TB (3A BEC) or similar and two Warp 4 (4 turn) or similar, as a low hassle, good value for money option.

Jürgen
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Old Oct 31, 2006, 06:31 PM
'FPV'er...not a "LOS'er
Vantasstic's Avatar
Las Vegas, NV
Joined Sep 2003
18,208 Posts
Quote:
Originally Posted by punkrockd
... and i want one of those gemini's havent seen those out here.
Ohhhhhhhh, you are seriously missing out then. I've been flying a Gemini for the last several months and IT IS my current favorite plane. They are a little hard to get in the U.S. right now. Ikarus USA is the distributer and they sell them before their container hits the states. There's a good post on the Gemini that Jurgen started. Take a look there. Sometimes there are group buys that are put together...that's how I've gotten mine. My problem is I can't keep a spare on hand...once anyone sees the Gemini fly they want one too...
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Old Oct 31, 2006, 08:28 PM
Purples a fruit
punkrockd's Avatar
Walnut Creek
Joined Aug 2006
1,283 Posts
i started posting in that thread. i sure want one and brain doesnt live that far from me.

i want one bad!!

btw twin star2 is my current favorite plane,, althou i dont plan on posting every flight i did fly today and had a great time entertaining some kids and another flyer happend to see me flyin and stoped. i feel great i think i might have influenced this gasser guy to go e-power.

anyway i'm a confident flyer and not do disrespect anyone but the twin star 2 doesnt need much space to fly at all. i flew mine in a basketball court. sure it was just circles but getting a plane to fly as slow as it can and to my abilities is the most fun, flying around is easy. but the slow limits of any plane i've had really entertain me.

happy fly-n
d
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Old Nov 06, 2006, 05:54 PM
Registered User
Herndon, VA
Joined Feb 2006
174 Posts
Question for you guys. Im pretty clueless when it comes to batteries so help me out if you can.

I was about to punt my Twinstar II in to the trash the other day. It just seemed like i was always crashing. I put steerable landing gear on it, and they work awesome, but when I'd try to fly it it seemed the LG completely weighed the plane down and I could never get off the ground right. So, i crashed a couple time, no real damage but I was just getting tired of small repairs after every flight, so I was about the retire the plane.

I happened to take out my 8 cell battery (which i normally kept in the plane) and saw that two cells were leaking. So i now figure my botched take offs werent from being over weight, but not having power from 2 cells.

Today I decided to stick in my 3 cell lipo just to give the plane one last chance. I know 3 cells is too much for the motors, but i couldn't have cared less at the time about the motors (she was about to be permanently strung up to the ceiling anyways). My esc could handle it fine, so I thought I was ok.
So i flew it today with the lipo ---- oh man, what a difference that diet made. I kept the throttle below half almost the entire flight. Had good air time and landings, and fun was had by all.

But then I took out the 3cell to find it slightly swollen and warm. I dont really understand why my 3cell would swell up like that if people are using 2 cells without any problems. I figured the 3 cell would be able to dish out more punishment than a 2 cell. The 3cell is rated at 15c btw.

Im not really concerend about the swollen lipo, im most concerned as to why it happened. I hate not understanding electronics. Its so hard to wrap my brain around for some reason.

Anways. With the successful (and fun) flights today, I may end up buying a new 2 cell batt for this plane. It may be saved from the air museum after all...
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Old Nov 06, 2006, 06:27 PM
SlopeHead
jcosta's Avatar
Lisboa, Portugal
Joined Jan 2004
2,882 Posts
Quote:
Originally Posted by aspencer80
But then I took out the 3cell to find it slightly swollen and warm. I dont really understand why my 3cell would swell up like that if people are using 2 cells without any problems. I figured the 3 cell would be able to dish out more punishment than a 2 cell. The 3cell is rated at 15c btw.
You forgot to mention the capacity of your Lipo pack and the props you are using if not stock. The current draw might be around 30 amps, due to motor overheating, etc.
If it is a 2100mAh pack, it is normal that it would be above limits.

OTOH, did you reprogram your ESC for 3 Lipo cells?
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Old Nov 06, 2006, 08:37 PM
Registered User
Herndon, VA
Joined Feb 2006
174 Posts
Quote:
Originally Posted by jcosta
You forgot to mention the capacity of your Lipo pack and the props you are using if not stock. The current draw might be around 30 amps, due to motor overheating, etc.
If it is a 2100mAh pack, it is normal that it would be above limits.

OTOH, did you reprogram your ESC for 3 Lipo cells?
Im using the Graupner cam speed props. the 5.2x5.2" found here http://www.hobby-lobby.com/elecprop.htm

I used the lipo from my brushless slowstick so its not that big - 1350 mAh

And im using this 35 amp esc (which i did remember to switch to 3 cell lipo)
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Old Nov 06, 2006, 08:40 PM
Curse you Red Baron!
Grassy Knoll's Avatar
North & East of Sacramento California
Joined Apr 2004
567 Posts
Quote:
Originally Posted by aspencer80
Question for you guys. Im pretty clueless when it comes to batteries so help me out if you can.

I was about to punt my Twinstar II in to the trash the other day. It just seemed like i was always crashing. I put steerable landing gear on it, and they work awesome, but when I'd try to fly it it seemed the LG completely weighed the plane down and I could never get off the ground right. So, i crashed a couple time, no real damage but I was just getting tired of small repairs after every flight, so I was about the retire the plane.

I happened to take out my 8 cell battery (which i normally kept in the plane) and saw that two cells were leaking. So i now figure my botched take offs werent from being over weight, but not having power from 2 cells.

Today I decided to stick in my 3 cell lipo just to give the plane one last chance. I know 3 cells is too much for the motors, but i couldn't have cared less at the time about the motors (she was about to be permanently strung up to the ceiling anyways). My esc could handle it fine, so I thought I was ok.
So i flew it today with the lipo ---- oh man, what a difference that diet made. I kept the throttle below half almost the entire flight. Had good air time and landings, and fun was had by all.

But then I took out the 3cell to find it slightly swollen and warm. I dont really understand why my 3cell would swell up like that if people are using 2 cells without any problems. I figured the 3 cell would be able to dish out more punishment than a 2 cell. The 3cell is rated at 15c btw.

Im not really concerend about the swollen lipo, im most concerned as to why it happened. I hate not understanding electronics. Its so hard to wrap my brain around for some reason.

Anways. With the successful (and fun) flights today, I may end up buying a new 2 cell batt for this plane. It may be saved from the air museum after all...
Aspencer80:

I would be very concerned with the swollen LIPO's.

Actually they are no good.

When a LIPO swells like that they are destroyed.

What happened is you caused the cells to drop below the 3v per cell.

While flying the LIPO got hot and swelled up.

So what you need to do now is dispose of it but in a safe way.

Since the LIPO is discharged (I am assuming you have not tried to recharge it) place it in a glass or bowl filled deep enough to completely cover the LIPO and then some.

Then pour in a few tablespoons of salt.

Let it sit over night.

THIS IS THE DANGEROUS PART
With the LIPO removed from the salt water bath, use a very sharp xacto knife and make a very shallow incision along the edge of the swollen covering.

Be careful not to cut to deep.

BE AWARE THAT IF YOU GO TO DEEP IT WILL EXPLODE INTO A BALL OF FLAME.

The incision will allow the gases to come out.
It will stink. Do not inhale it.

If you do not feel comfortable doing this than drop it off at a local fire station and they will dispose of it for you.

Brandie
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Old Nov 06, 2006, 08:43 PM
Sagacious flyer
Singapore
Joined Oct 2005
71 Posts
Wow!!! I have been busy thus has not been here for some while, and there has been so much "stress" in this thread.

Anyway, i am not sure if i have shared with your guys my video on the Twin Mega 4 Turn with Twin Jeti Advance Plus 30Amp ESC and Twin packs of Flightpower Evo 2100mAh 3Cell running in parallel.

Anyway, here is link to the footage. http://www.daddyhobby.com/gallery/sh...00&ppuser=1033

Do turn on the volume to your speakers to hear those motors screaming... yeah...

BTW, i have found a cheaper alternative that will give you the same performance.

2 x Himax 2815/2000 Brushless motors. With the same APC 6x5.5 or Graupner 6x4 prop, you will get to enjoy unlimitted verticle climb with such a huge plane.

Cheers
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Old Nov 06, 2006, 09:05 PM
SlopeHead
jcosta's Avatar
Lisboa, Portugal
Joined Jan 2004
2,882 Posts
Quote:
Originally Posted by aspencer80
Im using the Graupner cam speed props. the 5.2x5.2" found here http://www.hobby-lobby.com/elecprop.htm

I used the lipo from my brushless slowstick so its not that big - 1350 mAh

And im using this 35 amp esc (which i did remember to switch to 3 cell lipo)

OK, now we know what went wrong: 15C x 1350 mAh = 20.250 A. That is the maximum discharge rate of your battery. You forgot that the TS2 has 2 motors and so the current draw is definitely higher than 20A. With your props it's probably closer to 30A.

Also, half throttle does not reduce the current draw peaks, only the number of times those peaks are reached, because of how ESCs work (by switching on and off at a variable rate depending on the throttle position).

So, do not use a battery with less than a 30A discharge rate and even so I would give it a safety margin.

However, for the TS2, a battery with at least 3000mAh is what makes sense, so even a 10-12C Lipo will be enough at that size.


Hope you managed to understand everything, if not, ask away!
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Old Nov 06, 2006, 09:08 PM
Registered User
Herndon, VA
Joined Feb 2006
174 Posts
Im not all that concerned about the battery. I did let it set out on the sidewalk for a couple hours after taking it out. If i handed you the battery right now you wouldn't be able to tell it swelled. It looks perfectly normal, but after using it about 4 times a week for 3 months i can tell its slightly larger.

And I know for absolutely sure i programmed the esc correctly. And I cut the motor and glided in for a landed about 3 seconds after the lvc started cutting out the motor.

I brought it after letting it sit and used the multimeter on it and it read 10.9v.

I charged it up already and just took another measurement, it now reads 12.3v.

Its stored in a safe place except when its flying, so the only damage it might do is to a plane in flight (wouldnt that be cool looking!)
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Old Nov 06, 2006, 09:18 PM
Registered User
Herndon, VA
Joined Feb 2006
174 Posts
Quote:
Originally Posted by jcosta
OK, now we know what went wrong: 15C x 1350 mAh = 20.250 A. That is the maximum discharge rate of your battery. You forgot that the TS2 has 2 motors and so the current draw is definitely higher than 20A. With your props it's probably closer to 30A.

Also, half throttle does not reduce the current draw peaks, only the number of times those peaks are reached, because of how ESCs work (by switching on and off at a variable rate depending on the throttle position).

So, do not use a battery with less than a 30A discharge rate and even so I would give it a safety margin.

However, for the TS2, a battery with at least 3000mAh is what makes sense, so even a 10-12C Lipo will be enough at that size.


Hope you managed to understand everything, if not, ask away!
That helps a ton jcosta. I didnt understand that the c value times the capacity gives the max discharge rate. So just having a larger capacity battery allows for a great discharge rate.
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Old Nov 06, 2006, 09:36 PM
Will fly for food
Maryland
Joined Sep 2004
8,424 Posts
Quote:
Originally Posted by Grassy Knoll
So what you need to do now is dispose of it but in a safe way.

Since the LIPO is discharged (I am assuming you have not tried to recharge it) place it in a glass or bowl filled deep enough to completely cover the LIPO and then some.

Then pour in a few tablespoons of salt.

Let it sit over night.

THIS IS THE DANGEROUS PART
With the LIPO removed from the salt water bath, use a very sharp xacto knife and make a very shallow incision along the edge of the swollen covering.

Be careful not to cut to deep.

BE AWARE THAT IF YOU GO TO DEEP IT WILL EXPLODE INTO A BALL OF FLAME.
Realize that the salt water bath is NOT a good way to discharge the battery.. The current flow will corrode the tabs off the cells in short order.

a) Use a light bulb or resistor to fully discharge the pack.

b) dispose of the pack

Once the pack is fully discharged there is little danger from venting.

There is a thread on this in the Battery forum section.
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Old Nov 06, 2006, 09:52 PM
Purples a fruit
punkrockd's Avatar
Walnut Creek
Joined Aug 2006
1,283 Posts
coolmx,

nice power, but i think its a bit over kill considering the plane.

not to offend you but its my opion. just like all those guys trying to make a stryker fast.

but... and its a big but

the climb is awesome!!

i love the way my stock ts2 flys. i always fly it so low to the ground, reminds me of a cargo plane and it is more scale.

but then again the climb!!

anyway, one mans opinion
d
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Old Nov 06, 2006, 10:45 PM
Curse you Red Baron!
Grassy Knoll's Avatar
North & East of Sacramento California
Joined Apr 2004
567 Posts
Quote:
Originally Posted by Pinecone
Realize that the salt water bath is NOT a good way to discharge the battery.. The current flow will corrode the tabs off the cells in short order.

a) Use a light bulb or resistor to fully discharge the pack.

b) dispose of the pack

Once the pack is fully discharged there is little danger from venting.

There is a thread on this in the Battery forum section.
Actually if you re-read I said since the battery pack was already discharged.

I got the information about soaking the (discharged) battery from one of the many "How to dispose of a defective LIPO" threads.
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Old Nov 09, 2006, 08:45 AM
Sagacious flyer
Singapore
Joined Oct 2005
71 Posts
Quote:
Originally Posted by punkrockd
coolmx,

nice power, but i think its a bit over kill considering the plane.

not to offend you but its my opion. just like all those guys trying to make a stryker fast.

but... and its a big but

the climb is awesome!!

i love the way my stock ts2 flys. i always fly it so low to the ground, reminds me of a cargo plane and it is more scale.

but then again the climb!!

anyway, one mans opinion
d
Hey, i am cool. The important thing is we must all enjoy flying the way we like it. YOu like it slow, steady and scale. While i love to push it the air frame to the maximum power system that the plane can take.

I love to see such a big bird climb without efford. Its really cool just like my nick
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