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 Post subject: BEC failure issues
PostPosted: Mon 09. Oct 2023 15:18:40 
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Joined: Mon 02. Oct 2023 15:33:33
Posts: 10
I brought both the micro spirit and the spirit 2 earlier this year, I used the micro spirit on a align 250 (works fine) and the spirit 2 on a align 450, whatever BEC ESC (with the 450) I use, when I move the sticks on the transmitter the satalite (DSM2) fails and the lights start to flash. When I run spirit software Bec tests sequence all of the units fail. I have tried 4 different ESC BEC units on the system they all fail. I have even brough a couple of brand new ESC BEC all do the same. I have also replaced the servos with new ones (align DS353 tail DS 450 cyclic). I have even changes the satalites to no avail.
If I run the sytem from a 4.8 volt NIMh battery the system it all works fine. I have used several different BECs including an align 30A a hobbywing 30A and a couple of generic 40 Amp ESC BEC. I am beginning to think its the spirit unit failure as I have changed everything else. I have tried to contact info@spirit-system.com but the message gets rejected. The voltage
output from the BEC is about 5.6 and it looks clean on an oscilloscope.

Any ideas anyone. Chris


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 Post subject: Re: BEC failure issues
PostPosted: Mon 09. Oct 2023 16:22:48 
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Joined: Mon 29. Apr 2013 16:06:44
Posts: 12442
Hello, I replied to your email in the morning. You received reply, possibly in SPAM.

I am sending it again here:

Hello,

the problem can be resolved usually in a very cheap way - by adding a capacitor that will cover voltage drops. This solution costs roughly 1 USD.

The problem like this is happening when servos are drawing too much amps. Spektrum satellites are quite sensitive for this and when they detect voltage drop it will start to flash and could even disconnect transmission temporarily.
If the problem is even bigger the whole electronics could restart in flight. So it is very important to resolve it to avoid a crash.

The problem could be because of:
a) BEC that can't handle such current.
b) Wiring that is unable to carry required current.

Spirit 2 is very tolerant for voltage drops and basically only send voltage to satellites from BEC through a regulator to 3.3V.
So if Spektrum satellites will flash it mean your BEC voltage dropped even under 3.3V which is very big drop.

Since you already tried so many BECs I am inclined to case B.
Some servo connectors are not holding properly - especially when using Y cables voltage drops could be significantly bigger.

Do you use 2 BEC leads in both units? This will double the maximum current that servos can have. One servo cable can carry limited current, so connecting two is always safer.

Another thing when using external BECs - it is very dependent on how you are powering them. If powered directly from LiPo their max current is proportionally lower. So for example from 30A BEC that is really 30A at 7.4V you can get only 10A BEC. Then when you add factor of poor current transmission through a weak servo connection it could be just max 1A in the end.

For 250 and 450 class models current draw is usually not that high. Only very old ESCs from Align and Castle are not designed for todays servos. So their BEC will be not sufficient.
Please let me know what ESC exactly do you have. I am sure we can make it work in any case. There are more solutions.

Since you found it can work with NiMH battery it mean the unit is not a problem and it is just dependent on BEC/wiring that is used. NiMH battery is obviously stronger and makes voltage more stable.

Please note when you have 30A ESC it does not mean it has 30A BEC. The BEC could be only rated for 3A which is at the edge already when using todays servos.

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 Post subject: Re: BEC failure issues
PostPosted: Tue 10. Oct 2023 11:54:13 
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Joined: Mon 02. Oct 2023 15:33:33
Posts: 10
Tried a 60amp bec still trips the satalite. soldered another cable black and red (only aux 1 and 2) wire directly into the 40amp new BEC, still did not work. pulled out all the servos it ill only support one of them plugged into the spirit unit after that the satalite fails. The only thing I have not change is the spirit unit. it does work fine via the Nimh battery however.
lost for options here.
Chris


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 Post subject: Re: BEC failure issues
PostPosted: Tue 10. Oct 2023 12:23:56 
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Joined: Mon 29. Apr 2013 16:06:44
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Hello,

I am not sure how the wiring look like, but soldering two BECs together will lead in burn at some place sooner or later.

Do you have a different satellite cable?
Do you have more satellites to try?
Are they original Spektrum satellites?
The problem could be just weak connection between connectors of the satellite cable.

For 450 class model BEC rated to 5A is usually sufficient for any servos.

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 Post subject: Re: BEC failure issues
PostPosted: Tue 10. Oct 2023 12:55:58 
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Joined: Mon 02. Oct 2023 15:33:33
Posts: 10
I have just added an extra cable to the 40 amp so its only one BEC just doubled the current capacity.
so there should be no issue with the power circuit.
That is the total output from the ESC BEC (40 amps)

The satalites are orange DSM 2 2 off

Chris


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 Post subject: Re: BEC failure issues
PostPosted: Thu 12. Oct 2023 8:36:55 
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Joined: Mon 29. Apr 2013 16:06:44
Posts: 12442
Can you try only with one satellite or a different satellites if you have?

We have experience that some non original satellites could be partially faulty and draw too much current.
If you have a different satellite cable it could be helpful too. Sometime it is enough to replace them, because wire is internally damaged or connector has poor connection in the socket (even that it is holding very firmly).

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