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HomeAircraftHelicopterHelicopter Main Discussion › Will this work? Generator to charge batt under flying...
06-01-2012 04:19 PM  6 years agoPost 21
AirWolfRC

rrProfessor

42½ N, 83½ W

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Something like this is a good starting point,

http://www.ebay.com/itm/Marine-Alte...977ab63&vxp=mtr

Use a single 4S LiFePO4 12V battery and then select all your accessories to run on 12V-14V DC (standard automotive voltage).

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06-01-2012 04:31 PM  6 years agoPost 22
GetToDaChopper

rrElite Veteran

Las Vegas , NV

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You'll NEVER make enough electrical power to charge flight packs in the air.

If you're going to put a gas engine on it.make the gas engine the main power and then charge the RX pack with a generator.

I fly with a generator myself but no way in hell will it charge lipos powering the drive motor.
Well of corse not ! because that would be perpetual motion now wouldn't it ! lol

Watch at YouTube

    ▲
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▲ ▲ ▲ One of a Kind !!!

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06-01-2012 04:32 PM  6 years agoPost 23
Rototerrier

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Fayetteville, GA - USA

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Overkill. This will work as well and smaller, lighter, cheaper.

http://www.ebay.com/itm/1000V-50A-G...=item4166738985

Bridge Rectifier.

Gassers Rule, Nitros Drool, Electrics...uhhh...Joule?

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06-01-2012 06:44 PM  6 years agoPost 24
omj86

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North Cape, NORWAY

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Ac to dc? The Gen deliver dc.

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06-01-2012 06:53 PM  6 years agoPost 25
Rototerrier

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Fayetteville, GA - USA

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It looks like that big generator you listed does have a built in rectifier...but I think we all just assume you wouldn't use it cause it's so big and heavy. •Weight: 12.5 oz (354 g)

That's massive.

You can use a brushless motor with a rectifier and regulator and come out much lighter.

Up to you though. Yes, you can use the one you showed us from ebay and try to find a way to spin it at a constant 18k rpm. Let us know how that turns out

Gassers Rule, Nitros Drool, Electrics...uhhh...Joule?

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06-01-2012 07:49 PM  6 years agoPost 26
AirWolfRC

rrProfessor

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The larger brushless motors have lower KV's that would be needed for your application. Use a six diode bridge to recitfy and feed a 12V regulator to a 4S LiFePO4 battery.

The early C-130's had 3-bladed 15ft diameter propellers. Later versions had 4-bladed 13.5ft diameter propellers.

Using the 4-bladed version as a scale reference and 0.85 Mach for the tip speed, your 1/12 scale version will have a 14" 4 bladed propeller and a motor rpm of about 17,500 rpm. Most model applications don't use tip speeds that high.

A direct drive alternator with a KV of no more than 1000 can do the job. Closer to 500 would be better.

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06-01-2012 08:28 PM  6 years agoPost 27
omj86

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North Cape, NORWAY

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I dont think 350g is much in a 1:12 scale C-130?
And the 1:14 CL-215 is allready set up to be filled up with over 2 liters with water in the water thank...

In a plane at this size, i allso think that there will be room for a small enginge that I can have inside to run the Gen ONLY.
I can lock that at a sertain speed that gives the Gen 18k rpm.

Connecting the Gen to one of the main engines will be a problem because that engine will change RPM all the time and that wont make the Gen stabile.

Where can I find a small alternator?
Sorry for my bad english, but isnt that whats in cars? And dont they produce AC? (before it goes throu a converter that makes it DC before it reach the batt.?)...

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06-01-2012 11:29 PM  6 years agoPost 28
AirWolfRC

rrProfessor

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re-read my last post . . . especially the first paragraph.

Connecting to a main engine is preferable, since you only want 120 watts. That's about what a 0.049 glow engine puts out.

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06-01-2012 11:32 PM  6 years agoPost 29
McKrackin

rrProfessor

Lucasville,Ohio

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I don't think he was going to put a gas engine in it for decoration mate.
His illustration shows five multi cell battery packs that would only make sense driving the main motor.

We have already had the discussion with another guy that wanted to use a gas engine to power a generator to power four motors to fly a quad....Perpetual motion seems to be the in thing right now so I jumped a little too far with my conclusion...Even though the illustration posted BY THE OP shows battery power to everything and a gas engine to power a generator to charge the batteries powering everything else.

I made my assumptions based on being SHOWN the set up.

I literally never use the word literally right.

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06-01-2012 11:37 PM  6 years agoPost 30
omj86

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North Cape, NORWAY

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Np. My fault. Bad description.

I dont want only 120w, I want as much i can get,
but the Gen still needs to be small. That example was just
based on the gen i came across on ebay.

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06-01-2012 11:47 PM  6 years agoPost 31
omj86

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North Cape, NORWAY

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I will try to make a drawing of my plans with the
diffrent stuf i will have around so it can be easy to se what I need. Thanks.

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06-02-2012 02:23 PM  6 years agoPost 32
Rotormaster

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Australia

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We have already had the discussion with another guy that wanted to use a gas engine to power a generator to power four motors to fly a quad....
That is not perpetual motion. I think I have to say that this is even worse of an idea than trying to perpetuate motion.
Perpetual motion seems to be the in thing right now so I jumped a little too far with my conclusion...Even though the illustration posted BY THE OP shows battery power to everything and a gas engine to power a generator to charge the batteries powering everything else.
Haha, sorry, I didn't see the diagram before. I think I can excuse your assumption, because I'm now slightly confused myself...

Hehe, when I was little kid I was entirely convinced that I could create a perpetual motion machine. I would draw diagrams and I would often go to bed pondering what new experiments I could try with my crazy magnet contraptions.

By the way, the OP's gas engine will eventually run out of fuel... I think he should genuinely consider plumbing the exhaust to the carburetor. (j/k)

http://www.lhup.edu/~dsimanek/museum/unwork.htm

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06-02-2012 02:29 PM  6 years agoPost 33
Rotormaster

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Australia

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06-02-2012 02:33 PM  6 years agoPost 34
omj86

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North Cape, NORWAY

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...

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06-02-2012 04:14 PM  6 years agoPost 35
CX1

rrKey Veteran

Canada

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before you can decide on a generator you need to know your power consumption first.

using a common voltage for all components < such all electronics using a 12V battery then regulate down to match components.
once you have a common battery turn it all on and work the servos to drain the battery for 1 minute. then recharge and measure the mah that went back in.
once you figured your KW/h you can select a generator to provide power. The problem will be finding 1 small enough.

your car battery is charged by the engine running and if it works for cars it can work for planes

" Team Protoast "

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06-02-2012 04:17 PM  6 years agoPost 36
omj86

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North Cape, NORWAY

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That was just what i had planed to do

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06-02-2012 04:26 PM  6 years agoPost 37
jschenck

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La Vista, NE.

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already been mentioned but take a close look at this - unless you really want to invent the system yourself.

http://www.sullivanproducts.com/GenesysMainFrame.htm

Also could send a PM here to user 'rbort' - he has quite a bit of experience with on board charging systems. I have one from him works great. Primarily heli stuff but I'll bet he could either help or give some suggestions.

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06-02-2012 04:52 PM  6 years agoPost 38
AirWolfRC

rrProfessor

42½ N, 83½ W

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The Sullivan Genisys is a cute idea but has one major fault, it produces a maximum of 800ma and only 4.8V. Sullivan will design and build you a custom system to do exactly what you need but for a 4 digit price tag.

The rbort system also has a similar problem but not as bad. It has problems keeping up with a digital servo system on helis that draws about 2 amps or more.

I recently made a system that can keep up with 8 amps.

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06-02-2012 05:02 PM  6 years agoPost 39
Rototerrier

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Fayetteville, GA - USA

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4700uF Capacitor
http://www.ebay.com/itm/New-5x-Radi...#ht_3405wt_1163

Bridge Rectifier
http://www.ebay.com/itm/35-AMP-3-TH...=item5d2cb635b7

CC BEC Pro
http://www.castlecreations.com/products/ccbec.html#

Brushless Motor
500kv range as suggested based on the specs you have mentioned.

Piece it all together and you have a generator. Good luck.

Gassers Rule, Nitros Drool, Electrics...uhhh...Joule?

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06-02-2012 05:38 PM  6 years agoPost 40
AirWolfRC

rrProfessor

42½ N, 83½ W

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It's good that you're trying to be helpfull but how is one supposed to use the rectifier that you pointed out ?

The brushless motor / alternator has three wires and you still need two for the DC output. The bridge recrifier has only four terminals.

I guess you missed the part in my post yesterday where I said "six diode bridge" . . . your referenced bridge rectifier has only four diodes.

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