zeeshan

hello evryone im in the process of making a teher for the aerohawk from a 12volt gel cell battery(like the ones you use in your starter boxes for glow engines) i have orderd a few parts they are out of stock but i shall have them by monday i hope im using to light wires and im going to get the male conecter to plug it into the female connecter on the board one of the issues maybe that i need to get the c of g also i am going to be using a stepdown or a resistor to get it as close as i can to the 8.4 voltage like the stock battery i think i got it around there i have forgoten what powere the ereistor or the stepdown is i shall kepp you poisted
do any of you have any thoughts on this or any tips i would be glad to recive any information
thank you

jackclarke

Hope you are saving your allowance Zeeshan - cause it sounds like you are going to be buying a new speed controller - motors - mixer - as soon as you are tethered to that 12v gel-cel. Not wanting to discourage "creative thinking" but it might be advisable to have somebody explain how a dropping resistor only works when the current is CONSTANT. You might also want to have a closer look at the thickness of the wire on the Aerohawk battery connector and think about the weight and "drag" of 10 feet of that hanging off the skids. Good luck -

FHHuber

If you stick a voltage regulator in the line between the gel cell and the tether... it might work. You'd want to set the regulator maximum for 1.4 v/cell of the standard flight battery for the heli. (Aerohawk I think is 7 cell... that would be 9.8 v.)

zeeshan

i will put in the 5amp quick fuse just incase but i think this idea will work ive benn down to the electric dtore near hear and the person says it should wor k the only problem maybe the cofg which i can mend anyway but thanks for the information anyone else .

zeeshan

any ideas

zeeshan

so you think a voltage regulator will work not jus a resistor or a resistor

Banished Outside

It can work, however the 12v will probably fry the board, so a voltage regulator capable of 8A current rating would be needed.

I ran my Dragonfly on a variable bench power supply for months - eventually my all in one board gave up but I think it was more to do with flying time rather than excess voltage!

Steve

zeeshan

so a resistor weouldnt work

FHHuber

The resistor drops voltage only under the current load of the motor (in this case)... so when you start up the heli electronics... you'd be pushing the full (practically) 12 v to the circuit board. It would smoke for sure before the gyro/mixer initialized.

pthegr81

i was thinking of doing the same thing(tether),but with an ac-dc convertor.along the lines of a universal plug that you may use to power a discman or any other battery powered device.

even your 12vlt battery will die eventually,but this way would require no charging.

i have one that you can select voltages from 3-12vlts (one being 9vlts which sounds perfect) ,but it has a 1amp max.now if i can only find one that will supply 8 or more amps i know it can be done.

some site i was on had an aerohawk-like heli that they were selling WITH a tether included.could not tell you where though(did not have my aerohawk then).the video of it i watched showed it going at least 10 feet or so,but the wire gauge was smaller than the main board's.

10 feet would be plenty to learn to fly and practice hovering while charging.though it would have slightly diff flight due to tether.

UKgroucho

You're probably thinking of the XRB Lama - check Benthehens posting at http://www.rcuniverse.com/forum/who_...1710086/tm.htm

The one thing that no-one has mentioned in all this discussion is 'will the main motor take it'. I've seen numerous comments about letting the main motor cool down between packs. You're going to need to get a stable power supply that delivers approximately the same volts and amperage as a fully charged 700MaH NiMH to be happy with this type of set-up.

Why? Because anything less will likely feel sluggish and inferior to flying on batteries. The problem is that the power delivered by a battery pack drops as it becomes discharged - so the motor probably works a little less hard towards the end of the pack (my assumption, correct me if this is wrong . If you drive the motor with maximum power (available) continuously then I have to wonder if it will overheat within 15 - 20 minutes? Agreed you will be a little limited on throttle openings if you're doing this inside your house but I still question if overheating the main motor is a possibility.

Any thoughts?

pthegr81

as your battery dies you will have to give it more throttle to do the same thing,so im sure the motor worrks just as hard when close to dead.

but,letting your motor cool sounds like a good idea(couldnt be bad)

besides whats 5 mins of cooling compared to 1/2 an hour or more of charging.

the first night i got mine i flew(or tried)for hours nonstop with several baterries.but i have to say i have burned up that motor but not any more.

zeeshan

can the board fry just beacues it gets to hot also so what would you people recomend for me to connect this battery to the aerohawk to get it up and running.

FHHuber

Yes you can fry any IC chip by getting it too hot. Since the Aerohawk board has IC chips... it can overheat and die. (that's basicly how it dies from excess voltage... it heats up and the inside of the chips "melt".

pthegr81

i have read in the forums about some people placing a heat sink over one side of the main board

i have not tryed this,but i know i have ran my aerohawk without the main motors heat sink and it makes the diff in the motor being hot or just a little warm

Skypig

I did this with a Hummingbird. Ran it off a car battery and 25 feet of small speaker wire. Works great. Have over 50 hours on this setup. Made a heat sink out of soda can for the motor. No problems with the speed controller getting toasted. Have also done this with my Hornet and the speed controller, gyro, and reciever that came with it.
I hook up a batt charger to the car batt while flying to keep the battery from dying while flying. I have actually flown so long as to run the car batt down without the charger hooked up.
This setup made a great learning tool for orientation and backward flight.
GOOD LUCK!

pthegr81

what do you use to reduce voltage??

zeeshan

so if you use a 5 amp quick fuse will it stop the board from getting fried because it gets to hot. also to reduce woltage is what im trying to find out. lolz thank you

Skypig

I don't use anything to reduce the voltage except the wire itself. I had originally hooked it up with 50 feet of wire and it did not run at all. Too much resistance. So I cut the 50 feet in half and it worked perfect. Plenty of power and no fried boards. The wire itself acts as the voltage dropping resistor.

zeeshan

ive got 10 meters of it that i was planing to hook it up to what do you think
serioiusely thats amazing you sure tell us what you hooked it up to and evrything all problems solved
also what wire did you use ive got some not sure which size and if that one will work.

Skypig

I think it is 16 guage speaker wire. Got it at Radio Shack.

avance_x

You may want to use 7808 (+8V, 1Amax TO-220 package) voltage regulator. It's quite easy to make a circuit for it and don't forget to put a heatsink on it (i.e 7808 chip).
Make sure to provide a fuse between the source and the regulator

zeeshan

avance_x can you put that in ebglish for me lolz what parts and where can i get them from
Skypig are you sure that idea will work ive got 10 meters of wire im not sure what the size iz i think it is ... it dosetn say anywayz so yuo just hooked up 25 feet of wire to strips of them positive negative to what ???? a 12 volt gel cell or somthing elses.
thanks for all the replies

buster7467

My Feedback: (2)

did you mount your stock battery on your heli so the weight would be close to stock. I think that would be easier so it would not be that different in it's handling when you go to fly it with just your stock battery. If you understand what I am trying to say.

zeeshan

yep but i still need to find out the rest of the information on how to get this up and running.