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Old Apr 10, 2012, 03:38 PM
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Owatonna MN 55060
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Originally Posted by RGS2010 View Post
I got all of my wires together and connected last night and then connected battery for first time and NUTHIN happened.

I couldn't get any power to get the RX to bind at all. I would see a little flicker of power when I connected it at the connector but nothing to the RX.

I then went back to each nacelle and tried to bind to just one ESC at a time and nothing there either. I did this with both ESC's individually and same thing nothing. The only thing I can think of is that I have 2 bad ESC's!!!

They are both 50 amp Red Brick Opto ESC's from HK and although both of these are new, I've been using this type for two other planes with no problems.

It wouldn't matter how the motor wires are connected to the ESC except that the motor might turn opposite direction right?

Any other thoughts would be appreciated...

Russ
Most Opto ESC's don't have any BEC. What are you powering your RX with?
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Old Apr 10, 2012, 04:05 PM
If it's to be, it's up to me.
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Sydney, Australia
Joined Jan 2007
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Quote:
Originally Posted by RGS2010 View Post
I got all of my wires together and connected last night and then connected battery for first time and NUTHIN happened.

I couldn't get any power to get the RX to bind at all. I would see a little flicker of power when I connected it at the connector but nothing to the RX.

I then went back to each nacelle and tried to bind to just one ESC at a time and nothing there either. I did this with both ESC's individually and same thing nothing. The only thing I can think of is that I have 2 bad ESC's!!!

They are both 50 amp Red Brick Opto ESC's from HK and although both of these are new, I've been using this type for two other planes with no problems.

It wouldn't matter how the motor wires are connected to the ESC except that the motor might turn opposite direction right?

Any other thoughts would be appreciated...

Russ
Don't get frustrated, work through it step by step.

If you have 11.1v from the main power wires to the ESCs you should at least get beeps from them. Start by sorting that.

What do you mean by a "flicker of power". On some receivers, if you put the power lead in upside down you will get a flash from one of the RX LEDs.

Sub
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Old Apr 10, 2012, 07:15 PM
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WestTexasKing's Avatar
Monahans TX
Joined Sep 2010
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Sounds like the same problem I had with mine when I first got it.
I'd tell you how I fixed it, but I honestly have no idea what I did to fix it LOL
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Old Apr 11, 2012, 08:30 AM
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Houston, Texas
Joined Mar 2010
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Well it was a comedy of errors but I found it. It was one bad esc and one bad attention problem. I had esc wire connected with wrong extension cable. Got that esc with the HK bec on it to work fine. Then hooked up other and still dead. Put another esc on it (with red wire cut) and hooked both motors up and they worked!
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Old Apr 11, 2012, 11:29 AM
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USA, TX, Corpus Christi
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Quote:
Originally Posted by RGS2010 View Post
I couldn't get any power to get the RX to bind at all. I would see a little flicker of power when I connected it at the connector but nothing to the RX.

They are both 50 amp Red Brick Opto ESC's from HK and although both of these are new, I've been using this type for two other planes with no problems.

Russ
If they are Opto's don't you need a ubec or separate battery to the receiver?
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Old Apr 11, 2012, 12:05 PM
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USA, TX, Copperas Cove
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Originally Posted by jpflyer View Post
If they are Opto's don't you need a ubec or separate battery to the receiver?
Yes you do
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Old Apr 11, 2012, 12:42 PM
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Houston, Texas
Joined Mar 2010
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I have one

Yes I have an HK 5 amp BEC wired into one of the ESC's and the other one is an ESC with an onboard bec that I disabled by cutting the red wire. When I hooked 'em all together they played nicely and ran those motors smoothly.
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Old Apr 12, 2012, 08:37 AM
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United States, TX, Houston
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Joining the Jpower P-38 club

Put my order in to HK on Friday, oversized box is packed and should be shipping soon.... Can't wait!

Is the general consensus here that a BEC should be added immediately (i.e. before the first flight?). My understanding this is (partially?) to ensure both motors stop at the same time when the battery gets low?
I intend to limit my first flights to ~5minutes with the Turnigy 2200MAH battery , then check the voltage.
What ending V should be the aim for a flight, leaving some margin for go-arounds and not running them too low?



Quote:
Originally Posted by RGS2010 View Post
Yes I have an HK 5 amp BEC wired into one of the ESC's and the other one is an ESC with an onboard bec that I disabled by cutting the red wire. When I hooked 'em all together they played nicely and ran those motors smoothly.
Can you give a link or model number for your BEC?
I've seen this BEC/LVC one mentioned here:
http://www.dimensionengineering.com/products/smartbec

thanks! The P-38 has always been my dream plane, hopefully will have many, many enjoyable flights with her!
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Old Apr 12, 2012, 11:11 AM
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Grand Rapids, MI
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I use the smartbec on my p-38 and think its a wise investment. Luckily, I havent had to "use" it yet, but I did test it with a low battery pack and indeed both engines slowed at the same rate instead of one cutting off before the other.

You're ending voltage should be 11.1 minimum for a 3s. Figure your time based on how long it takes you to get down to that at full throttle. I've timed my flights for a 3s 2200mah to around 6.5 minutes.
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Old Apr 12, 2012, 11:27 AM
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United States, MD, Salisbury
Joined Dec 2007
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I just ordered the airframe only P-38 from BH. It comes with the motors. I was wondering would 25 amp ecs' work ok. I needed a new P-38 as I crashed my Phase 3 veteran by doing a roll and having the battery fall out! A real shame!
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Old Apr 12, 2012, 12:13 PM
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Houston, Texas
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I would use 30 amp or above.
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Old Apr 12, 2012, 12:16 PM
Always Fly 2 Mistakes High!
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Houston, Texas
Joined Mar 2010
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[QUOTE=Kurt;21308136]Can you give a link or model number for your BEC?
I've seen this BEC/LVC one mentioned here:
http://www.dimensionengineering.com/products/smartbec

http://hobbyking.com/hobbyking/store...dproduct=16663

Here ya go. Just remember to cut the red wire on ESCs with the BEC built in after you add the separate BEC.



Russ
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Old Apr 12, 2012, 12:25 PM
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United States, CO, Colorado Springs
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Quote:
Originally Posted by Kurt View Post
Is the general consensus here that a BEC should be added immediately
Minor clarification:

A separate BEC is used to power the rx and servos. This is a Good Idea becasue 1> this airplane has a lot of servos, and 2> running two built-in BECs in parallel sometimes causes problems. (depends on the brand) There are other ways to deal with the problem, but a stand-alone BEC is one of the simplest and safest.

A separate LVC is used to ensure that both motors cut off together when the battery is low. Also a Good Idea. Again, there are other ways to deal with the problem, but the stand-alone LVC is one of the safest.

The SmartBEC linked above serves both purposes. I use one on my 38 and also on my 262 and another EDF twin.
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Old Apr 12, 2012, 12:57 PM
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United States, TX, Houston
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Thanks much for the replies Hornetnz, RGS, and rdeis, very helpful!
Why don't both motors cut out together on the stock P-38, does each ESC have it's own LVC?

Think I'll go ahead and order a SmartBEC now, would hate to chinz out on $25 and then kick myself later...

BTW - I've already ordered pusher/puller props from Tower to do the counter-rotation mod recommended by http://z8rc.blogspot.com/2011/11/p-3...-rotation.html
Couldn't find much in this thread about this, is it not the general consensus that it serves any useful purpose?
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Old Apr 12, 2012, 06:17 PM
If it's to be, it's up to me.
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Sydney, Australia
Joined Jan 2007
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Quote:
Originally Posted by Kurt View Post
Put my order in to HK on Friday, oversized box is packed and should be shipping soon.... Can't wait!

Is the general consensus here that a BEC should be added immediately (i.e. before the first flight?). My understanding this is (partially?) to ensure both motors stop at the same time when the battery gets low?
I intend to limit my first flights to ~5minutes with the Turnigy 2200MAH battery , then check the voltage.
What ending V should be the aim for a flight, leaving some margin for go-arounds and not running them too low?
A conventional BEC is not going to prevent one ESC hitting a Low Voltage Cutoff point before the other. You could use a separate BEC and disable the two in the ESCs, but most don't bother. The voltage outputs of the two (identical) BECs in the ESCs are so close that they do not fight each other. In my experience they are fine to use and provide ample current for the entire system.

Best practice for determining how long you should fly is to observe how many mAh go back into each pack after a short initial flight, and calculate how long you can fly based on that. Stay under 80% of the battery capacity and you'll always have enough reserve for a go around or two, or a particularly "sporty" flight.

I link my timer to my throttle so it counts down when throttle >20%. I think I time for 7 minute flights on a 3S 2200. I never put more than 1760mAh back in.

HTH
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