Anybody use two packs for speed 400 twins? - RC Groups
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Apr 19, 2001, 03:59 PM
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Anybody use two packs for speed 400 twins?


I was thinking on making a twin speed 400 plane and using two power systems mixed together on the radio. How does this sound? Two speed 400 6V on 8x600AE each?
Dan
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Apr 19, 2001, 04:08 PM
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Heavy
Apr 19, 2001, 04:09 PM
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Larry Dudeck's Avatar
Sounds like a lot of additional work, esp. if you plan on 2 ESC's.

What benefit do you perceive?
Apr 19, 2001, 04:33 PM
Registered User
Well I have a lot of 600mah packs.....
Apr 19, 2001, 04:34 PM
Single-task at best...
tim hooper's Avatar
Dan,

Digging deep here.....I think someone has done this with a Twinstar. A seperate ESC for each motor, somehow mixed into the Tx.

He was able to throttle each motor independently, and induce such tricks as high-speed flat spins.

I'm sure that somebody will be able to shed more light.

tim

Bingo! Email Jim Myers;

KMyersEFO@aol.com

and ask for a file of the Ampeer newsletter from July 99.

[This message has been edited by tim hooper (edited 04-19-2001).]
Apr 19, 2001, 04:38 PM
Registered User
I just checked the specs and 2 8 cell 600 AE packs works out to 10.4 ounces. An 8 cell 2400 pack weighs 18 ounces, and a 8 cell 1200 pack weighs 12 ounces.
It would just be the extra weight of a controller which is less than one ounce. It could actually be lighter.
Dan
Apr 19, 2001, 04:46 PM
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earm what if one pack discharges faster then the other?
Apr 19, 2001, 05:22 PM
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Sabrejock's Avatar
Dan: If you want to use your 600 packs and don't want to go series, 'Y' your packs in parallel to give you 1200 mAh and still use BEC. You can charge them as individual packs. Tex.
Apr 19, 2001, 05:31 PM
Registered User
Thats theother otion, but then I need a 16 cell controller.
Apr 19, 2001, 06:20 PM
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Sabrejock's Avatar
Dan, if you join your packs pos to pos, neg to neg, and take the power from there, you still have 8 cells in reality. That's parallel. Tex.
Apr 19, 2001, 06:36 PM
Senior Member
Good question, what happens if one flattens first? Assemetric thrusts, that's what. With a pinwheeling prop on the other side (heaps of drag) this COULD be dangerous!

You could wire them up in parallel. This is the option i'd choose as you only need one ESC and that can be a standard 8-cell one.

If you're interested in assymetric thrust for steering, you'd need to wire things up so you had a Y lead like a delta. You'd have throttle on the "Elevator" channel and rudder on your "aileron" channel. I don't know how you'd go about sorting the power supply for the radio, though. Obviously you could use the BEC's in the ESC, but i haven't a clue how it might be effected by this extra complexity!
Apr 19, 2001, 10:06 PM
Registered User
Parrallel like Sabrejock says would probably be theeasiestway, I was thnk series together weoud be 16 cells, or series seperately would be 2 8 cell packs. Maybe I should just buy some 1250's
Dan
Apr 19, 2001, 11:51 PM
Registered User
I read somewhere about a Twinstar with the motors wires in parallel and 2 battery packs wired in parallel. This would be the simplest way to do it and use your existing equipment.
Apr 20, 2001, 05:37 AM
RIP Azarr - "Old age is not for sissies"
Azarr's Avatar
I've done the mixing twice now, but both times with two speed controls and only one battery. The systems worked well, with all mixing done in the transmitter, mixed to the rudder stick so that rudder stick movement causes one motor to speed up, the other to slow down, depending on the location of the throttle stick, it can be quite dramatic. I did this successfully on the TwinStar, but my attempt at converting a JC Hobbies fun bat was not as successful, not because the mixing didn't work, but because we never could get it in the air, even with a bungee. There was obviously enough power to fly, it wanted to pull out of your hand, I think the airfoil was so thick that we just couldn't get it going fast enough at launch. It looked OK though, here's a pic.

Azarr
www.azarr.com

OK, for some reason I can't get the photo to appear, let's try this:

<a href=http://albums.photopoint.com/j/View?u=94931&a=12646387&p=46897672>See my photo, twinbat1 at PhotoPoint</a>

[This message has been edited by Azarr (edited 04-20-2001).]
Feb 27, 2004, 02:22 PM
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fprintf's Avatar
So this was this first post in this forum eh? Cool!