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Pumpkin drop event

ESC brownout after gyro addition

utnuc

New member
#1
Hello FT community! Long time reader, first time poster.

I just put together an FT Tiny Trainer with the recommended power pack A, and have had a blast flying it in a local park. It has been amazingly resilient to crashes. The park where I have been flying is located on a large hill that seems to be frequently gusty, so I decided to install an A3 Pro v2 6 axis gyro to give me some more stability on the worst days. Install and setup went smoothly, and I added the included 3300uF/16V capacitor to the bind plug on my OrangeRx r620x receiver to smooth out the BEC voltage. Here's the rundown on the equipment:

  • Motor - EMax - MT1806
  • EMAx BLHeli - 12A
  • Servos - 4x EMax ES9051 5g Servos
  • Gyro - HobbyEagle A3 Pro
  • Battery - Tattu 3s LiPo Battery 75C
  • Receiver - OrangeRx r620x
  • Transmitter - Spektrum dx6 g3

First flight: the plane flew 5 feet and the ESC browned out. Lost communication, and motor cut out. As I approached the plane, I can hear it reconnect as if I've just turned it on. Subsequent flights revealed the same result, all done with the 4 servo setup (sport wing). Dropping the A3 gyro gain to as low as 20% gave the same result at the default servo refresh of 50Hz. If I put the gyro into disable mode it all works normally, no cut-outs. Additionally, with the motor off I can get the ESC to brown out by shaking the gyro in stabilization mode. Moving the capacitor to the various ports on both the gyro and receiver does not fix the issue. The ESC hangs loose in the front of the plane, just behind the motor and is getting plenty of ventilation, and the brown out happens suddenly and early ruling out overheating.

This seems to narrow down the problem to the 1A BEC on the BLHeli. After reading from several well written threads on this forum, I suspect that the 1A BEC is unable to handle the load when all 4 servos are twitching around to compensate for multidirectional wind gusts despite the the capacitor helping. Some have even written that 500mA is probably closer to the capacity this ESC can handle.

Which of these solutions would you recommend:
  • Get a bigger ESC - If this is your rec, which one?
    • BLHeli 20A gets a 2A BEC
    • HobbyKing 40A gets 4A UBEC
    • other option where the rated BEC is closer to reality
  • Get a dedicated BEC and battery - this seems like overkill
  • Get a bigger capacitor - this seems like a bandaid solution to a larger problem
  • Return the A3, noobs shouldn't use a gyro
I'd prefer to actually get this working rather than calling it quits with the gyro, and I hesitant to test the setup much more for fear of damaging my current ESC.

Penny for your thoughts, thanks in advance.
Ben
 
Last edited:

DamoRC

Well-known member
Mentor
#2
First, nicely written question with good context and all the relevant information.

I would go with the 4A option. I think the 2A will cover your needs but under high loads you may be cutting it close. The 40A with the 4A UBEC will be a little heavier, but it also future-proofs you for larger models with multiple 9g servos.

DamoRC
 

Hai-Lee

Old and Bold RC PILOT
#3
Hello FT community! Long time reader, first time poster.

I just put together an FT Tiny Trainer with the recommended power pack A, and have had a blast flying it in a local park. It has been amazingly resilient to crashes. The park where I have been flying is located on a large hill that seems to be frequently gusty, so I decided to install an A3 Pro v2 6 axis gyro to give me some more stability on the worst days. Install and setup went smoothly, and I added the included 3300uF/16V capacitor to the bind plug on my OrangeRx r620x receiver to smooth out the BEC voltage. Here's the rundown on the equipment:

  • Motor - EMax - MT1806
  • EMAx BLHeli - 12A
  • Servos - 4x EMax ES9051 5g Servos
  • Gyro - HobbyEagle A3 Pro
  • Battery - Tattu 3s LiPo Battery 75C
  • Receiver - OrangeRx r620x
  • Transmitter - Spektrum dx6 g3

First flight: the plane flew 5 feet and the ESC browned out. Lost communication, and motor cut out. As I approached the plane, I can hear it reconnect as if I've just turned it on. Subsequent flights revealed the same result, all done with the 4 servo setup (sport wing). Dropping the A3 gyro gain to as low as 20% gave the same result at the default servo refresh of 50Hz. If I put the gyro into disable mode it all works normally, no cut-outs. Additionally, with the motor off I can get the ESC to brown out by shaking the gyro in stabilization mode. Moving the capacitor to the various ports on both the gyro and receiver does not fix the issue. The ESC hangs loose in the front of the plane, just behind the motor and is getting plenty of ventilation, and the brown out happens suddenly and early ruling out overheating.

This seems to narrow down the problem to the 1A BEC on the BLHeli. After reading from several well written threads on this forum, I suspect that the 1A BEC is unable to handle the load when all 4 servos are twitching around to compensate for multidirectional wind gusts despite the the capacitor helping. Some have even written that 500mA is probably closer to the capacity this ESC can handle.

Which of these solutions would you recommend:
  • Get a bigger ESC - If this is your rec, which one?
    • BLHeli 20A gets a 2A BEC
    • HobbyKing 40A gets 4A UBEC
    • other option where the rated BEC is closer to reality
  • Get a dedicated BEC and battery - this seems like overkill
  • Get a bigger capacitor - this seems like a bandaid solution to a larger problem
  • Return the A3, noobs shouldn't use a gyro
I'd prefer to actually get this working rather than calling it quits with the gyro, and I hesitant to test the setup much more for fear of damaging my current ESC.

Penny for your thoughts, thanks in advance.
Ben
I had the same problem many years ago but I was not using the gyro. Mine was caused by aggressive flying and when all servos where activated at the same time the BEC would just collapse in voltage and the model would crash

Ideally you should have a 2A BEC for the TT as 1A doesn't make it unless all of your servos are small, (3.7 gram or less). You could use a separate UBEC which could be connected to the same battery and the BEC could power all Electrics with the BEC of the ESC disconnected and not used. That would simplify things a little.

Have fun!
 

utnuc

New member
#4
Thanks for the quick replies fellas, a testament to helpfulness of this community.

@DamoRC I'll look into this one, but I don't have any shrink wrap, xt-30 connectors or banana plugs laying around, so I might just go simple with a prebuilt esc that can handle 3A. Looking at the FT 20A ESC, I wonder if it can really handle 3A.

@Hai-Lee If I went with a separate UBEC would I need to get a xt-30 y connector off the battery? My biggest beef with this solution is space. It's already tight in the tiny trainer with everything I've got crammed in there now. I'm sure it'd be fine with a flying wing or something with more storage space.
 

Hai-Lee

Old and Bold RC PILOT
#5
Thanks for the quick replies fellas, a testament to helpfulness of this community.

@DamoRC I'll look into this one, but I don't have any shrink wrap, xt-30 connectors or banana plugs laying around, so I might just go simple with a prebuilt esc that can handle 3A. Looking at the FT 20A ESC, I wonder if it can really handle 3A.

@Hai-Lee If I went with a separate UBEC would I need to get a xt-30 y connector off the battery? My biggest beef with this solution is space. It's already tight in the tiny trainer with everything I've got crammed in there now. I'm sure it'd be fine with a flying wing or something with more storage space.
You could find a plug to fit into the balance plug of the battery and power your separate BEC from the balance plug. The bec could be located with the Rx if the wires were made long enough!

On my TTs I use 3.7 gram servos off of a HK 12A ESC with a 1A BEC intergrated.

Have fun!
 

FDS

Well-known member
#6
You don’t need a Y connector for the separate BEC, you just splice an new pair of wires into the two from the battery plug to the BEC.
I never run less than a 3A bec in my ESCs, it’s not worth having less on a 4ch, I would rather have spare capacity.
 

FDS

Well-known member
#8
Yes. Digital servos are much more power hungry. You also really don’t need their rapid response in most FT designs, apart from some of the 3d ones.
I just use the cheap plastic gear analogue ones in nearly everything.
 

utnuc

New member
#10
@FDS my next build will be with analog micro servers, thanks

@kilroy07 great info in that thread, thanks. I saw that you used a cheap buck converter as an external BEC. It looks like a fantastic conclusion to stop using the onboard heat producing internal ESC BEC, supported by @Hai-Lee 's rec.

I think I've decided to go with an external BEC powered off the battery directly, and it seems like a rip off to go with one of the HobbyKing BEC units considering how cheap these buck converters can be had. So I'll be in for a little soldering and shrink wrapping. Do you think something like either of these would work for the step down:

https://www.amazon.com/dp/B01GJ0SC2C/?tag=lstir-20
https://smile.amazon.com/Erayco-LM2596-Converter-3-0-40V-1-5-35V/dp/B07JNQFV7F/

I guess I'll need a futaba connector for the output and somehow splice into the xt-30 connector from the ESC or the battery balance connector. This option would save me having to worry about the output side

https://smile.amazon.com/2-Pieces-Hobbywing-Switch-mode-UBEC-Helicopter-Quadcopter/dp/B01GHMW0C0/

@kilroy07 how'd you splice into the battery? @FDS can the typical balance connector handle a 3A draw? The wire gauge looks too small to handle that much on my Tattu 3s.
 

Hai-Lee

Old and Bold RC PILOT
#11
@FDS my next build will be with analog micro servers, thanks

@kilroy07 great info in that thread, thanks. I saw that you used a cheap buck converter as an external BEC. It looks like a fantastic conclusion to stop using the onboard heat producing internal ESC BEC, supported by @Hai-Lee 's rec.

I think I've decided to go with an external BEC powered off the battery directly, and it seems like a rip off to go with one of the HobbyKing BEC units considering how cheap these buck converters can be had. So I'll be in for a little soldering and shrink wrapping. Do you think something like either of these would work for the step down:

https://www.amazon.com/dp/B01GJ0SC2C/?tag=lstir-20
https://smile.amazon.com/Erayco-LM2596-Converter-3-0-40V-1-5-35V/dp/B07JNQFV7F/

I guess I'll need a futaba connector for the output and somehow splice into the xt-30 connector from the ESC or the battery balance connector. This option would save me having to worry about the output side

https://smile.amazon.com/2-Pieces-Hobbywing-Switch-mode-UBEC-Helicopter-Quadcopter/dp/B01GHMW0C0/

@kilroy07 how'd you splice into the battery? @FDS can the typical balance connector handle a 3A draw? The wire gauge looks too small to handle that much on my Tattu 3s.
Either of the regulators would suffice IF you remember to set the voltage prior to connection and hopefully the adjustment never varies or has a failure. Plus you need to add the wires and the insulation.

If I was seeking a UBEC for a TT weight and ease of use would be a high consideration and so I would order the 5V version of this:-https://www.aliexpress.com/item/2017-New-Hot-Selling-BlueSky-DC-DC-Converter-Step-down-Module-3A-5V-Mini-UBEC-for/32930708758.html?

Have fun!
 

utnuc

New member
#12
Either of the regulators would suffice IF you remember to set the voltage prior to connection and hopefully the adjustment never varies or has a failure. Plus you need to add the wires and the insulation.

If I was seeking a UBEC for a TT weight and ease of use would be a high consideration and so I would order the 5V version of this:-https://www.aliexpress.com/item/2017-New-Hot-Selling-BlueSky-DC-DC-Converter-Step-down-Module-3A-5V-Mini-UBEC-for/32930708758.html?

Have fun!
This is a good option, thanks for the link. Seems simple enough to solder to the battery pos and batt neg leads of a balance connector. For the battery side, do you think the balance connector could handle a full 3A draw? Those wires can't be more than 18g.
 

Wildthing

Well-known member
#13
If you are going to solder directly to one I would solder the leads to the esc not the battery otherwise you can only use that battery with that plane. Getting an end to match the balance plug and going through it is the best way.
 

utnuc

New member
#14
If you are going to solder directly to one I would solder the leads to the esc not the battery otherwise you can only use that battery with that plane. Getting an end to match the balance plug and going through it is the best way.
I was thinking about soldering in a 3s balance connector, rather than to the battery itself. Ordered three of the blue sky 5v ones for $9 on banggood just now.
 

utnuc

New member
#15
I just realized that I had also planned to add a voltage/thermal telemetry probe that uses the balance connector. I've have two options to connect both with one solder job.
  1. For ease of connection I could just splice the tele probe and BEC to the ESC xt-30 connector directly. Only downside to this approach would be that these three components would be tied together, limiting future modularity.
  2. If I tied them all into a 3S balance plug I'd only be able to use the BEC and tele probe with a 3S battery.
I know there's no right or wrong answer here, just thinking it through. Leaning toward option #1 since I might be using a 2S, 3S or 4S battery with any specific FT build.
 
Last edited:

Wildthing

Well-known member
#16
If you have any 2 terminal plugs of any kind you could add that inbetween the xt30 connector and the bec and probe that way you can unplug one or all from each other.
 

Hai-Lee

Old and Bold RC PILOT
#17
The 3A UBEC I mentioned has a pair of JST connectors. They can be cut off and reused when making the battery connection, (regardless of how you connect it) and then if you wish to remove it you could just unplug the JST connectors and unplug from the Rx.

The connection to the Rx could be made simply by reworking a spare bind plug!.

The thin wires are short and their resistance is quite low so the heating is also quite low, They are only a little less in diameter than the wires used on the JST plugs which can handle around 10A. The UBEC only handles 3A.

Have fun!
 

kilroy07

Well-known member
#18
Either of the regulators would suffice IF you remember to set the voltage prior to connection and hopefully the adjustment never varies or has a failure
I second that! (Especially about the set the voltage FIRST!) Not that I've smoked an esc or anything... :rolleyes:
A dab of hotmelt glue will hold the value for you once you've got it set.

Here's what I picked up for smaller builds;
https://www.aliexpress.com/item/10P...795.html?spm=2114.13010708.0.0.3a994c4do4VYpj

Here's how I usually have a light setup
IMG_8760[1].JPG

An example of "the total package"
IMG_8755[1].JPG

And two other examples
for the planes I care a bit more about
IMG_8756[1].JPG
And the big girls
IMG_8759[1].JPG
 

utnuc

New member
#19
Got the blue sky 5v BEC in the mail today. Soldered one of the JST connectors and my battery voltage telemetry leads to the xt-30 connector. Removed the red lead on my ESC throttle connector and shrink wrapped it. Soldered a spare Futaba plug onto the 5v side of the BEC. Plugged the ESC throttle lead back into the receiver, then the BEC into the bind plug and into the JST plug on the battery lead. Everything works perfectly, no brown outs. Thanks for the help. I've actually axed the TT and put the electronics in a scratch built Mighty Mini Arrow.
IMG_2841.jpeg
 

kdobson83

Well-known member
#20
Got the blue sky 5v BEC in the mail today. Soldered one of the JST connectors and my battery voltage telemetry leads to the xt-30 connector. Removed the red lead on my ESC throttle connector and shrink wrapped it. Soldered a spare Futaba plug onto the 5v side of the BEC. Plugged the ESC throttle lead back into the receiver, then the BEC into the bind plug and into the JST plug on the battery lead. Everything works perfectly, no brown outs. Thanks for the help. I've actually axed the TT and put the electronics in a scratch built Mighty Mini Arrow.
View attachment 131877
Looks nice. I'm getting ready to scratch build my 4th Arrow, bringing this one to FliteFest this year. Will be my first trip.
Anyway, you may wanna add some color to your arrow. That solid black is hard to keep orientation, trust me!! Lol Good luck on the maiden.