How many amps with 8717 / 8900 setup ?

[chosen69]

I have a question concerning the amperage that those servos draw, because I bought a Flightpower receiver pack (2S2P 7.4 3000) http://www2.towerhobbies.com/cgi-bin...?&I=LXRWF3&P=0 and was gonna connect it to the 6A BEC to power my 8717 / 8900.
The questions is:

1. how many amps is this setup goin to draw ?
2. will those thin battery wires plus deans micro connectors be enough to transfer the current or will the whole thing just melt through ?

anyone ? Thanks !!

[dsmit258]

I would be interested to know the answer too. I have the same setup, and am using a Align 2N1 regulator (also 6A). I haven't had any problems with it to this point.....

[chosen69]

Originally Posted by dsmit258

I would be interested to know the answer too. I have the same setup, and am using a Align 2N1 regulator (also 6A). I haven't had any problems with it to this point.....

are you using the flightpower reciever pack as well ? If so, how did you connect it to the BEC , Deans Micros ?

[ronlund]

It would depend on your flying style and your setup. Typically, there wouldn't be any problem, however, if you have any of your servos or linkages in a bind, the amperage goes up dramatically.

After you get the heli built, try this. Unplug the regulated power to the receiver. Power the receiver with a 4.8v NiCd battery by just plugging it directly into the receiever. Also plug a voltage monitor into the receiver.

Using the transmitter, move each servo to it's limit. The voltage should be the same when the servo reaches the end of it's travel. If the voltage drops, back off the travel limit a little and check again. Do this with each servo.

If you go for a really wild setup, you can expect some binding if you move the cyclic stick into the corners at full positive/negative . I wouldn't worry too much about that.

[chosen69]

Originally Posted by ronlund

It would depend on your flying style and your setup. Typically, there wouldn't be any problem, however, if you have any of your servos or linkages in a bind, the amperage goes up dramatically.

After you get the heli built, try this. Unplug the regulated power to the receiver. Power the receiver with a 4.8v NiCd battery by just plugging it directly into the receiever. Also plug a voltage monitor into the receiver.

Using the transmitter, move each servo to it's limit. The voltage should be the same when the servo reaches the end of it's travel. If the voltage drops, back off the travel limit a little and check again. Do this with each servo.

If you go for a really wild setup, you can expect some binding if you move the cyclic stick into the corners at full positive/negative . I wouldn't worry too much about that.

Thx Ronlund, that sounds like a real good plan.
I'm worried as well about those thin wires that come out of the receiver Lipo battery if they can handle that kind of amperage ? On the other hand the wires that are soldered to the BEC are the same size and it's is rated for 6Amps. I'm just not sure how many amps the setup with all those high power servo's will draw under load... and I wouldn't like to find out on the maiden that it was too much ...

[wicked0ne]

Did you ever find out the answer to your question? I'm running the same setup and was wondering how many amps the 8717's draw

Originally Posted by chosen69

Thx Ronlund, that sounds like a real good plan.
I'm worried as well about those thin wires that come out of the receiver Lipo battery if they can handle that kind of amperage ? On the other hand the wires that are soldered to the BEC are the same size and it's is rated for 6Amps. I'm just not sure how many amps the setup with all those high power servo's will draw under load... and I wouldn't like to find out on the maiden that it was too much ...

[chosen69]

Originally Posted by wicked0ne

Did you ever find out the answer to your question? I'm running the same setup and was wondering how many amps the 8717's draw

No, not up to now, even though I think many guys run a similar setup. But it seems that nobody ever had any problems ... ? I still would like to know though !

[Super D]

Hello All- I run the same setup and the most I can get it to draw is 8 amps that is if I hold the swash still and jam on the sticks. I am currently running the 2in1 and 8717's with the 7703d and matching servo. unloaded and jammingh on the sticks i am pulling around 3.5 amps. hope this helps!!
D

[chosen69]

Originally Posted by Super D

Hello All- I run the same setup and the most I can get it to draw is 8 amps that is if I hold the swash still and jam on the sticks. I am currently running the 2in1 and 8717's with the 7703d and matching servo. unloaded and jammingh on the sticks i am pulling around 3.5 amps. hope this helps!!
D

Finally someone has mercy to our questions....! :-)) but wow, 8.5 amps seems a lot, doesn't that harm the BEC (2in1) and/or the wires cause I thought 6amps is the max it can handle ? Oh, and thx for helping me / us out !!

[chosen69]

By the way, how do you like the 7703d ?

[Super D]

No problem!! Yeah 8.5 amps is a lot BUT that was with me holding them in a stall. in my opinion you will never have that much force @ the swash. I was worried about the 2in1 being able to handel it also but so far so good no issues yet! KNOCK ON WOOD!! 1 thing I can deffinitly say is watch your reciever pack im only getting around 4 flights out of the Align 1900mah pack. so keep a close eye on that! other than that all is good!!

As far as the 7703D I like it alot im having some setting issues with it. I am useing a 9303 and the gyro sensativity menu in there and have it set around 60%. when im flying it will start to shutter so im trying to figure that out? any suggestions?

[chosen69]

Originally Posted by Super D

No problem!! Yeah 8.5 amps is a lot BUT that was with me holding them in a stall. in my opinion you will never have that much force @ the swash. I was worried about the 2in1 being able to handel it also but so far so good no issues yet! KNOCK ON WOOD!! 1 thing I can deffinitly say is watch your reciever pack im only getting around 4 flights out of the Align 1900mah pack. so keep a close eye on that! other than that all is good!!

As far as the 7703D I like it alot im having some setting issues with it. I am useing a 9303 and the gyro sensativity menu in there and have it set around 60%. when im flying it will start to shutter so im trying to figure that out? any suggestions?

I'll definitly watch my reciever pack, but its a Flightpower Reciever pack 3000mah Lipo so I'm guessing/hoping that I'll get at least 4 Flights out of it if you get 4 out of the align pack !!

Concerning the 770, I haven't tried it yet but looks like many people have problems setting it up right so I was looking for a thread / video on how to set it up right but couldn't find one... maybe we can get Finless Bob to make one which would sure be great ...!! If you now a good thread on how to set it up that sure would be awesome cause I just ordered a 9303 as well. From reading the 770 manual it's not so much different from the 401 that I'm used to though. Sounds like that your servo arm length is important though and try to get it right on in rate mode then supposingly you won't have problems in HH either, at least thats what they say.... Thanks again for your help though !!!

[apisg]

Hi all,

I use the following setup on a Vibe 50:
- 3 X DS8717 for cyclic
- 1 X DS8717 for throttle
- Logictech 6100G + Servo combo
- R921, DSM2 receiver
- Align 2in1 Linear regulator (6 Amps) + VR5203 Spectrum Dual Output Gyro Regulator
- Battery 2S LiPo, Align 2150 mAh, 7.4V

I did the following current requirement measurements at the battery output (not regulator output - regulator also consums current):
On the ground:
- Idle current requirement (no stick movements in any collective position): 0,8 Amps
- Continued fast movements with both sticks end to end: 8,2 Amps
During flight:
I have many times forced fast vertical movement of the heli from full positive pitch (+11deg) to full negative pitch (-11deg) facing no problems with power (I assume this is worst case scenario).
Battery Requirements:
Using a fully charged (and balanced) battery (Align 2150 mAh, 7.4V) for a sinlge flight of 10mins duration it required 284mAh to fully charge the battery back. The latter equals to a current consumption of 1.7A on average for 10mins.

So far although Align 2in1 supports nominaly up to 6 Amps I have not faced any problems - approximately 20 flights for my new Vibe 50.
In general linear regulators such as 2in1 tend to drop the output voltage when the Amp recuirements are highly increased.

[rupps5]

I am running the set up in my sig and each flight uses about 350-400 mah

edit: and that draw is with about 7 minute flights

[jeffk]

I likewise did the same current-measuring-while-wailing-on-the-sticks test and didn't even get all the way up to 3 amps at 6V on the cyclics and 5.1v on the tail (actually around 2.8A total tested between the pack and the receiver). I didn't intentionally bind my servos (why risk burning them out?) but I did put a reasonable amount of pressure on the horns (till the servos were buzzing pretty good). The most additional amperage draw I noted from the additional pressure was about .1 amps per servo. So, figure 3.5 amps max under normal flight loads.

I've been flying 10-12 minute flights with mild 3D and consistently taking out an average of 215 mAh per flight or so. That's with at least 15 seconds worth of draw from the glow igniter at the start of each flight too.

I haven't bothered to test for amperage draw of a binding servo, since I figure that if I've got a servo that's bound up, I've got other, more urgent problems to deal with.

[rupps5]

2. will those thin battery wires plus deans micro connectors be enough to transfer the current or will the whole thing just melt through ?

if you are worried about the whole thing melting you could add you own connectors to other flight power batts that have the thicker wire.

like this one:
http://www3.towerhobbies.com/cgi-bin...?&I=LXSRT1&P=7
or this one
http://www3.towerhobbies.com/cgi-bin...?&I=LXRVS4&P=7

[chosen69]

I have to admit that I almost forgot about this thread that I started. First of all I would like to thank you guy's for taking those measurements ! Since I started this thread I've been flying my setup for around 100 flight's ( 4 x 8717, 770 + 8900 powered by previously described EVO receiver battery and the align 6A BEC) and haven't had any problems whatsoever ! Average MAH draw on a 10min flight is aorund 300. From what you guy's said I'm probably working close to the limit when flying 3D but it seems that if there's no servo binding I'm still maneuvering WITHIN limits. Just for peace of mind I will be changing to a different battery (thunderpower 2S2P 4200) which I just ordered. here's the link:

http://www.horizonhobby.com/Products...=THP42002S2PPL