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10-13-2005 11:27 AM  12 years agoPost 1
Liron alm.

rrApprentice

Israel

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hi
i'm new to the electric heli field, but not to nitro ones...
i own a raptor 90 se and a millennium 2 90.

i just bought a used mikado logo 16. bought it cheap but i have no clue on motors li pos and stuff.

i know that a speed controller is controlling the amount of voltage delivered to the motor. i also know that a BEC is used to deliver the receiver with 5v from the main batt pack, but thats about it

i bought the heli with a Aveox 1412 and Schulze 45bo speed controller.
is this a brushless set up? if not, must i replace it?
the guy i bought it from use a 16 cell ni-cad 2000mah. i think i'll go with the li-po setup. can i use 2 packs of 11.1v 3 cell lipo in serial configuration? if so, how can i charge them? do i need to charge them separately? also, is this motor good enough for mild 3D?

also, i thought about replacing the entire head with the raptor 30 one...
it looks like the head system is very poor. is it possible? will the raptor head fit the 10mm mikado shaft?


i can really use ANY info on electric helis, any article will be great.
i browsed throu some posts here but i couldnt find any basic material for me to understand..

thanks

liron

fly hard, land harder

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10-13-2005 06:21 PM  12 years agoPost 2
tean

rrApprentice

Gloucestershire,UK

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Hi Liron,
Welcome to the world of electrics.
Rule number one in this world, is that everything for large electric helis, like the one you have, is horribly expensive, so be certain that anything you buy is really going to work in your heli, BEFORE YOU BUY IT!

Rule number two is the motor, controller, battery and gear ratio, all have to be matched together to work well. Change any one of them, and you may end up changing everything.

Rule number three says that, once you get it right with an electric, you won't want to fly glow stuff again.

Yes, your motor is a brushless set up. I'm not familliar with Aveox motors, but you can find data on your Schulze controller at:

http://www.schulze-elektronik-gmbh.de/index_uk.htm

It appears you have an aeroplane controller. That means it will not have a governer (constant rpm) mode, so you'll have to control the motor with throttle curves in the same way as a glow motor.

Your controller is only rated to 18 nicad cells. That's 21.6 volts. Lipo cells have a nominal voltage of 3.7volts (4.2volts max), so the biggest battery you can use with your controller is 5s. That's 5 cells in series to give 18.5V (21V max). If you use two 3s packs in series to give 6s, you will exceed your controller's max voltage. The extra voltage from a 6s pack will also make your motor run faster, so you may have to change the gearing as well. (See rule two above).

Before you spend your life's savings on lipo batteries, I suggest you take some time to read up on them. There's lots of info on the web. Lipos are very easily damaged and can even catch fire if not treated correctly.Try starting at:
http://www.thunderpower-batteries.c...l/charging.html
http://www.flightpower.co.uk/
http://www.mikado-heli.de/
http://www.logoheli.com/

I wouldn't hurry to change your Logo's head. Mikado's rotorheads look very old fashioned, but they work very well.

I would suggest you get your logo flying as it is now. It should fly OK with the nicads, just with short flght time. Do some research as to whether your set up will suit your flying style and upgrade it as needed. If you're into aerobatics, your controller may turn out to be a weak point. You might want upgrade it so you can use bigger batteries (6, 8, even 10s?) rather than buy a small lipo now. Take the long term view. It'll work out cheaper.

regards
Andy

Logo14 Vbar, Logo500 CSM flybarless, Trex 600 CSM flybarless, 3DMP, Logo10, Lipoly, Mini T, .......

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10-13-2005 06:44 PM  12 years agoPost 3
Liron alm.

rrApprentice

Israel

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tean, thanks for your great answer!
i red that the li-po can catch a fire and you need to be extra carfull handling them, so i think i'll go with the ni-mh configuration.
strange... the guy said that the ESC keeps the rpm constant...

thanks again!

liron

fly hard, land harder

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10-13-2005 07:31 PM  12 years agoPost 4
Rob_T

rrElite Veteran

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If those nicads are the older "full size" sub-C cell, which I expect they are, you can now get a 3800 nimh cell that's the same size and with the same (or slightly better) discharge ability (but they are a few grams heavier). That will almost double your duration straight off. Alternatively you can now get a 4/5 sub-C with 2200 capacity, which also has virtually the same discharge capability and is lighter.

I think your controller will handle 6S lipo. The usual rule is to divide the number of nicads by 3 to get a maximum number of lipos.

3 nicads are about 4.5V fresh off the charger, which is more than the 4.2V of a lipo cell. Under load the lipo will be 3.7V and the nicads 3.6V (or lower!), but its the maximum voltage that determines if the FETs in the ESC will break down.

Aveox motors are made in the USA, and were one of the more respected names from a few years ago. Recently its not a name you see very often! See http://www.aveox.com for info on your motor.

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10-13-2005 08:10 PM  12 years agoPost 5
tean

rrApprentice

Gloucestershire,UK

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I wouldn't be put off using Lipos by the fire risk. I don't think they're dangerous as long as they're treated correctly. After all, most of our mobile phones have got them inside and they don't catch fire.

Lipos are vastly superior to nickel batteries for helis. To give you some idea, my VoyagerE used to fly for 9 mins on 8Nimh 3300 cells. I changed to a 3s2p lipo and now get upto 20mins and more power as well. My Logo10 used to go for 4 mins on 13, 2400mAh nicads. I've had over 17mins from a 5s2p lipo that's not as heavy!

Be put off by the price.....but not the safety.

Andy

Logo14 Vbar, Logo500 CSM flybarless, Trex 600 CSM flybarless, 3DMP, Logo10, Lipoly, Mini T, .......

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10-16-2005 11:13 PM  12 years agoPost 6
GroundPounder

rrVeteran

South Africa, Cape Town

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Rule number three says that, once you get it right with an electric, you won't want to fly glow stuff again.
Not to knock you Andy, but the battery hassle, is well, hassle :-)
Let's see, I get maybe 8 - 12 minutes on my T-Rex, then wait an hour for the battery to charge.
Or I can get another pack, and it is 30 min between flights, etc, etc
The Rexxie uses relatively cheap packs, to fly a 30 or 50, or heaven forbid, a 90 size machine like I fly and fuel my Raptor 50, well that would take a HUGE outlay in capital.

Liron, don't even consider other batteries than LiPo, the power density on these buggers run circles around any other chemistry.
Just use the correct charger, correctly, :-), and you won't have a problem.

GroundPounder

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10-17-2005 08:33 PM  12 years agoPost 7
Rob_T

rrElite Veteran

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Lipos are great for micro helis, and for any heli where you want the best power to weight ratio. But if you want the best, you end up paying for it!

For a 30 to 50 size heli the lastest nimh cells (like IB3800 and GP3700) are not so far behind in power density as to be totally unthinkable. They cost much less than lipos, can be charged quickly and can deliver more current (zapped cells can be discharged at upto 200A!).They also tolerate being abused, over charged, over discharged and can be balanced without special equipment (and while you can start fires with them, they are a lesser risk than lipos).

It all depends on where you need to be on the price/performance curve. I like lipos and use them in all my helis, but the price of them does sometimes make we feel some pain!

(PS I think one heli where the lipos vs nimh debate will really come to life is the Century Swift. When the batteries cost 3X the price of the heli, you really need to ask if there is any point in a low priced mid-size electric? Nimhs are the only way that the Swift will make sense, otherwise just buy a Logo!)

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