I recall seeing an article somewhere where you could buy a generator to attach to your engine. This would keep batteries charged and operate any other electrical devices such as lights etc.

Anyone every seen one of these in real life?

Wings

Sullivan makes something called the Genesys that powers your RX, charges your battery, and drive any onboard eqquipment at the same time. Rediculously priced, though. $200 I think???

I still have one in the crate by Tetra called Dynastar AP 3. Bought it quite a while ago. i'll look around the net to see if they're still in business.

The Genesys (sp?) system can be purchased from Tower Hobbies. Just saw it the other day in the 2004 catalog.
Dennis-

Still rediculously priced.

I can get one for you for $80 plus $4 shipping. PM me if interested

You can probably make one yourself...

These on board generators are wind driven, not driven by the engine. (at leat the ones I have seen.)

Go to Radio Shack and get a 12 volt DC motor. (about $3) Adapt some scrap computer fan onto it. (free)

Go here: http://www.uoguelph.ca/~antoon/gadgets/gadgets.htm and get the plans for the voltage regulator. Build it.

Add a diode or two to prevent the battery being charged from sending power backward through the regulator (if it isn't already protected... I think it is)

Strap it on and off you go.
*******

Now the practical side of it:

Its a bunch of added weight and you can just plug your plane into the field charger for 15 min between flgihts instead. If you aren't trying to set an endurance record, you may be better off not putting it on. for Aux items... a second 700 mah NiCd RX pack would be lighter and wouldn't add the drag.

Is it new?

I may be interested later, but am kinda broke now.


Wings

The Sullivan is driven by the engine's rotation.

Seems the are expensive, but wouldn't be nice not to have to worry about charging the RX battery? You could fly all day long.

I'm at a loss to explain why anyone would want to use one. It adds weight and is more complicated than using a field charger.

Ya, I didn't think about the weight.

Guess a field charger would prabably be better, but I don't have one so I wasn't thinking of that either.

Good Observation

wings - you only need one field charger. If you depend on an onboard system to charge your batteries, then you need one for each plane. Personally, I think onboard chargers are a relatively useless gadget. If I had a lot of scale accessories that needed power then it might be worth it when compared to the weight of a larger or separate battery pack.

I agree

I don't know guys... $109.99 from Tower http://www2.towerhobbies.com/cgi-bin...?&I=LXFV20&P=0

5.5 OZ according to Sullivan http://www.sullivanproducts.com/GenesysMainFrame.htm

I have to admit I'm tempted... I agree is a bit overboard for most pilots, but a good if not desired piece of gear for large scale enthusists...

I am imagining all of the pointless little lights and gadgets I could put on my plane... haha

a generator kit is available here in the u.k.it costs £13.50-about 20 u.s.dollars,is that cheap enough?they sell all sorts of r.c. electronics,their website address is-www.micronradiocontrol.fsnet.co.uk

I have bought a quick charger since starting this thread. MikeL brought me to my senses. Why add weight and more problems when you can buy a quick charger to use with all your planes.

they would make a good addition to an electric plane that would have enough RPM to get it to charge. then you could fly until your TX ran low. I would think anyway.

This can't work...

An electric motor is typically 80% efficient. 80% of the electric power absorbed in the motor gets converted to mechanical energy, 20% goes to friction and "I^2 *R" losses. (both make heat)

A generator is just a motor that is being turned instead of the motor turning the load.... you have the same 80% average efficiency.

About 90% of your motor's mechanical power would be going to pulling the aircraft through the air. So 10% of the mechanical power is going to be available to drive the generator. Now you have lost 20% of the electrical power to the inefficency of the motor... and just have 8% of the original electric power driving the generator... the generator loses 20% of that... so you now have 6.4% power going back to recharge the batteries.

You'd at BEST gain 30 seconds of cruising speed flight if the battery tended to give 10 min of flying. BUT... you added the weight of the gnerator... so you probably end up with a shorter total flight time.

fhhuber, SSSHHH!! you ruined my perfectly good perpetual motion machine dream!!! [8D]

Shows how much I know huh. Oh well just a thought. I sometimes dont think past my nose.

Just remember:
1) you can't win.
2) you can't break even.
3) you can't leave the game.

Have a thermo day

That would be like putting alternators on the wheels of your car and expecting to go further. Energy is neither created nor destroyed. It only changes form from potential (stored) energy to kinetic (work) energy and losses.

Hybrid cars transform kinetic energy to electicial energy when braking. The engine is then assisted by electric motors when driving. But this is just utilizing energy from the engine that would otherwise be lost to heat. You still need the engine.

FHHUber is correct. The motor transforms the potential energy of the battery to kinetic energy to the prop in the form of thrust and losses due to friction and heat.

But even if the motor was 100% efficient (no losses), you would still have to charge the battery because of the energy that is transformed to thrust.

I'm not trying to sound like a nerd but just try to paint a better picture of why it won't work. They key point is that energy is niether created nor destroyed. You can't get more out of something than you put in. If you did you would be filthy rich! We could eliminate those crooks selling us gasoline.

Ok i get it......