700 Size Power: BEC or RX Pack?

[Raptorapture]

Originally Posted by bredler

Whoa there buddy. Your heli's gonna crash! That voltage indicator only costs like $3!!!

[ve7nly]

My personal preference is the straight 2S lipo for a couple of reasons.
1) I feel the wiring is simpler and I like simple. Just plug the lipo into the FBL controller and done. In fact, if I have the room for extra plugs, I'll plug it into 2 locations on the FBL controller just for an extra sense of security. Plus it has the bonus of being able to fill in empty servo connection points and helps keep everything tight.

2) I like the fact that I can plug in the 2S lipo, and never have to worry about the transmitter accidently activating the throttle. Yes I know that you can have all kinds of safety switches to keep that from happening but this way I don't need to worry about any of that. And I can work in any flight mode that I need to and not have to unplug motor leads or move the pinion gear from the main gear.

Yes I know it means having an extra battery to charge, it can lead to more weight, and you have to run HV (meaning more expensive) servos but I feel that running a separate 2S lipo works better for me

[Mercuriell]

Originally Posted by Ace Dude

Why would you put a switch between the BEC output and the on-board electronics?

I have a switch between my buffer pack and on-board electronics, but never thought about putting one between the BEC and on-board electronics.

So you can hook up the main packs, put on canopy or cover and then walk the heli out to the flightline. Also powering up the gyro with the heli in its take off positions prevents sudden power up movements.

[jhamel]

Originally Posted by JesusFreak

I thought Aligh was bundling Castle ESCs with their packages now?

I believe that changed within the past year. It is my understanding that Align now uses rebranded HobbyWing ESCs in the combo kits instead of Castle ESCs. However, it looks like the Align rebranded ESCs are a bit watered-down when compared to the "real" HobbyWing ESCs.

[HeliSoCal]

Put an r2 on it and call it a day

[Ace Dude]

Originally Posted by Mercuriell

So you can hook up the main packs, put on canopy or cover and then walk the heli out to the flightline. Also powering up the gyro with the heli in its take off positions prevents sudden power up movements.

Thanks for sharing. Never thought of doing it that way.

I'm using a Kontronik ESC with a buffer pack & Futaba HD switch harness between the buffer pack and electronics. On the flightline I turn on the switch harness, let the gyro initialize, and then connect the main leads from the battery to the ESC.

[crasher47]

Originally Posted by ve7nly

My personal preference is the straight 2S lipo for a couple of reasons.
1) I feel the wiring is simpler and I like simple. Just plug the lipo into the FBL controller and done. In fact, if I have the room for extra plugs, I'll plug it into 2 locations on the FBL controller just for an extra sense of security. Plus it has the bonus of being able to fill in empty servo connection points and helps keep everything tight.

2) I like the fact that I can plug in the 2S lipo, and never have to worry about the transmitter accidently activating the throttle. Yes I know that you can have all kinds of safety switches to keep that from happening but this way I don't need to worry about any of that. And I can work in any flight mode that I need to and not have to unplug motor leads or move the pinion gear from the main gear.

Yes I know it means having an extra battery to charge, it can lead to more weight, and you have to run HV (meaning more expensive) servos but I feel that running a separate 2S lipo works better for me

I do the same with my 700 and two 600s using Pulse 2550mah 2S lipo and Spektrum 2200 mah LIFE on the 600's because of 6 volt servos. Many flights and no problems. Charging an extra battery is not a problem for me. On one of the 600's I had a ESC heating problem so I run a fan attached to the ESC and power the fan off the Life.

[JesusFreak]

Any of you who are running a simple 2S pack into HV components run into voltage drop issues/brown outs?

[Relisys190]

Originally Posted by JesusFreak

Any of you who are running a simple 2S pack into HV components run into voltage drop issues/brown outs?

Never in 260 flights on my Goblin 12S machine.


But I dont use a true Rx pack (which i've heard have low C ratings.
I use a 30C 2S lipo with low IR numbers capable of supporting some amperage.

[Thunder Fighter]

Originally Posted by Relisys190

Never in 260 flights on my Goblin 12S machine.


But I dont use a true Rx pack (which i've heard have low C ratings.
I use a 30C 2S lipo with low IR numbers capable of supporting some amperage.

+1.

The Lipos sold as Rx packs I've tried were terrible with large voltage drops, using standard 25C+ packs means voltage drops are minimal. I usually set my voltage alarm to 7.4v and it doesn't trigger till the pack is down below 50% used.

//Dennis.

[im4711]

all depends on the BEC. For smaller helis with 8V BEC I simply use BEC. On larger once and specifically the more costly systems I am using BEC with backup option (in my case Optipower Ultra Guard). And I do have still one where the BEC does not deliver 8V so I use a 2s battery instead.

[dominator]

Originally Posted by JesusFreak

Any of you who are running a simple 2S pack into HV components run into voltage drop issues/brown outs?

Never. But I have had an external bec fail and watched my heli fall from about 200ft up like a lawn dart.. Which is why I only run 2s lipo direct now.

[Xfreak3D]

why stil need a bec when Esc now has 12s bec built in like a kosmik or hobbywing.. i guess the new scorpion esc wil hv bec too..lesser one lipos to handle.. no need to worry you forgot to bring rx pack to field .

12s built in bec provides the easiest wiring too

[exiged]

Originally Posted by Relisys190

nice and light. How many flights can you get on it?

I usually limit to 3 flights on my 2200mah 2S. It yeilds 4.00 volts per cell after 3 flights. Safe and plenty of headroom for voltage sag.

I bring two 2200mah to the field and get 6 flights on the big bird.

I was using a 2200 also but decided to make my 700 a lighter machine by stripping a few bits off it and reducing the rx pack size.

I get 3x 4:40 flights from a 1000mah pack (nanotech 25-50c) leaving around 70% in it, so i could squeeze another 1 or 2 probably.

Ive never had the back up guard kick in during flight and these packs weigh next to nothing

[exiged]

Originally Posted by JesusFreak

How "safe" is it to use HV servos and just run a 2 Cell LIPO? I read someplace this was risky. On my 700 size Heli I use a ReactorX (which I'd love to find another of), with a 3 cell lipo.

I want to setup my new heli as simple as possible, but not risk failure. I have a 7200BX, which is not designed for high amp service, but my thought was I could run the power leads directly to the servos and bypass the receiver. I did something like this on my TREX 500, but it's been awhile. My biggest concern is that a simple 2 cell lipo may suffer a sag in voltage and do me in.

i run the AR7200BX on both my helis with a 2s lipo straight into the fbl unit. ive never had an issue. i always now run a backup guard (ultraguard), for the sake of £40 a back up guard is essential in my opinion whichever set up you go for, but 2s lipo is the way forward for me.

[cyclo]

Originally Posted by exiged

i run the AR7200BX on both my helis with a 2s lipo straight into the fbl unit. ive never had an issue. i always now run a backup guard (ultraguard), for the sake of £40 a back up guard is essential in my opinion whichever set up you go for, but 2s lipo is the way forward for me.

I have a very similar setup on my 700 helis... Currently using a 2S 1800 mah 25C Zippy Compact lipo plugged directly to A77200BX via two leads plus an Optipower UG for backup. I also have telemetry to warn me of low voltage conditions.



My smaller helis are powered by internal/external BECs. All have been reliable... Knock on wood.