DoubleCH's flight log

[DoubleCH]

Just did some testing switched AE 45A ESC to output SBEC at 6V setting and measured actual output with just an Orange 6ch Rx as the only load to 6.12V which is not bad at all. I'll go ahead put a diode to the tail servo and set SBEC output to 6V. Too bad weather won't be good for flying until a low chance on friday or a higher chance on sunday but I'm happier now.

[stevebaker]

I thought you said your stock esc only dropped to 4.85V in another thread.
What did you use / how did you determine that? - was you just measuring on the bench?
I wonder if you're missing logging very short drops in voltage and wonder if you simply had a faulty ESC.

[DoubleCH]

The 4.85V was tested with a simple Digital Multimeter and some simple bench test. I could not confirm if it ever dropped below that in flight.

I don't believe it was just a bad stock ESC. Even with the Turnigy AE 45A ESC with 4A SBEC that runs 5.3V in 5V mode dropping down to 5.1V (multimeter test) I still had a couple incidences that could've been the same problem. Probably just because the better BEC recovers quicker. That's why I've been running another external BEC at 5V mode for redundancy. Like I said, I've also tried powering the BX and stock servos with a 1S 550mAh battery at 3.82V for some bench test and there was no funky behavior even at this voltage so I'm pretty sure BX is not the culprit. That plus everything else I've observed from all my testings I was 99% sure it was BEC dropping voltage too low. EEngineer's findings just perfectly match what I've found from all my testings.

[stevebaker]

I would have also had money on it being your ESC/BEC. Funny you still had a problem with the Turnigy.
I would still conclude from this that your stock ESC was faulty or your servos are binding or are faulty and drawing too much, as I have had zero troubles with my stock ESC since last July and I've been flying it a lot in that time, including mild 3d (tic tocs etc etc) and in temperatures between about 5C and 10C this winter.

Anyway, I'm glad you sorted your problems out and you have provided excellent information for anyone else suffering with similar problems

[SHYguy]

Putting a cap on the BX, would that help?

If you still have problems maybe you should try with a receiver battery, just to eliminate that it could be a faulty BX?

Seing all these brownout problems I REALLY feel I should opt for a receiver battery in my 700!!! And the 450 batteries I alrady have fit that task Multi-purpose!

[wadders248]

Well I installed the same ESC on my 450x running at 6v, stock servos and a Scorpion 2221-6 10T and it works just fine.

The first battery was just a tentative amble around the field, progressively upping the head speed. The second battery was just how I'd fly normally. I'm not a hardcore 'smack' 3D'er, though I can tic-toc pretty well, long fast rainbows etc, so the ESC was definitely working hard.

Adding the governor gives you just a bit more control and is a bit easier on the batteries.

Everything came down cool to touch, so once I've flown it for a while I might go to an 11T pinion, though I don't really need and more head speed. I'll have to get one of my buddies to tach it so I know exactly what I'm getting.

[wadders248]

This is also a really cheap route to running a six cell setup in a 450!

One thing I have noticed is that the when the ESC initialises, the motor beeps are enough to spin the main blades slightly. This is something I've only ever seen with really efficient ESCs and motors like Kontronik.

[DoubleCH]

Originally Posted by stevebaker

I would have also had money on it being your ESC/BEC. Funny you still had a problem with the Turnigy.
I would still conclude from this that your stock ESC was faulty or your servos are binding or are faulty and drawing too much, as I have had zero troubles with my stock ESC since last July and I've been flying it a lot in that time, including mild 3d (tic tocs etc etc) and in temperatures between about 5C and 10C this winter.

Anyway, I'm glad you sorted your problems out and you have provided excellent information for anyone else suffering with similar problems

My servos are fine, especially after HH replaces one of my servos that is suspicious. The funny thing is the problem occurs usually not when the servos are loaded. Out of the 50+ flights so far if it survives the 1st minute of the flight, I can push it as far as I can like this one and have no fear of the problem.
[ame]https://youtu.be/JDVRwsqQwqs[/ame]

[DoubleCH]

Originally Posted by SHYguy

Putting a cap on the BX, would that help?

This will make it worse. It's actually because of "the big yellow cap" inside BX that EEngineer has been talking about on the 450X forum that takes time to charge up after voltage drop that BX freaks out. I tried adding a "voltage protector" cap to an empty servo port and it made the problem even worse. Instead of just short fraction of a second loss of control, the time period will actually get longer.

If you still have problems maybe you should try with a receiver battery, just to eliminate that it could be a faulty BX?

As I said I'm very confident running my AE 45A ESC/SBEC with 6V output will fix the problem as it has been proven by others on the 450X forum. If the problem still occurs I may try running my redundant external SBEC again but this time it'll supply only to the BX and everything else runs SBEC from ESC. This is not easy to do because I'll have to unpin all the red leads from all servos and hook them to the ESC's BEC output. That's why I've never tried this or a separate Rx pack.

Seing all these brownout problems I REALLY feel I should opt for a receiver battery in my 700!!! And the 450 batteries I alrady have fit that task Multi-purpose!

Or maybe run HV servos. My 450 Pro DFC is HV-ready for the cyclic (7.2V) and maybe I'll drop voltage down to 6V for the tail servo and run everything HV, just like running my 300X at 6V. The 450 has already been running 6V with CC 10A BEC so once I'm 100% sure 6V in my 300X fixes the problem I'll have no fear putting the BX on my 450.

[DoubleCH]

Originally Posted by wadders248

This is also a really cheap route to running a six cell setup in a 450!

And with 2 Nanotech 3S 45C 1300 packs in series...

One thing I have noticed is that the when the ESC initialises, the motor beeps are enough to spin the main blades slightly. This is something I've only ever seen with really efficient ESCs and motors like Kontronik.

I actually turned down the ESC beeps to 70 from default 100 and startup power from 1.00 to 0.25 on BLHeli. Even at 70, the beeps are pretty loud. And even at 0.125, motor spools up nicely but to be safe I set it to 0.25.

[stevebaker]

Originally Posted by DoubleCH

This will make it worse. It's actually because of "the big yellow cap" inside BX that EEngineer has been talking about on the 450X forum that takes time to charge up after voltage drop that BX freaks out. I tried adding a "voltage protector" cap to an empty servo port and it made the problem even worse. Instead of just short fraction of a second loss of control, the time period will actually get longer.
.

Wow, I didn't expect that - I would expect a smoothing capacitor to have the opposite effect. I'll have to get my text books out, it's been a few years...
I'll consult my mate who's an electronics wizz and see what he has to say

What capacitor exactly did you drop across the servo port?

[SHYguy]

Well I'm a car dude, and I recall the first Spektrum 2.4 GHz receivers had some glitch problems. A cap on a free port solved it for many.

OTOH I trust you guys' skills! How about removing or replacing the built in cap then?

Pack in my 700 for sure! ESCs and BECs do fail

[DoubleCH]

What EEngineer found perfectly explains the situation. The problem here is not due to ripple in supply voltage like the RC car case SHYguy suggested. Ripple in supply voltage has greater influence on analog circuitry. Nowadays, electronics especially sophisticated ones with mostly if not all digital signal processing circuitry are more prone to VUS as EEngineer calls it undershoot of supply voltage even for just some micro seconds or even nano seconds. Read his thread on 450X section. Lots of great info. I know to most people it sounds like he often over-analyzes electronics stuff on the bench but I trust his EE knowledge (I'm an EE as well). Remember these MCUs run in the tens if not hundreds of Mhz clock cycles. In 1 micro second, the MCU processes tens if not hundreds of instruction codes.

I've run 4700uF (voltage protector sold by HH) and 330mF supercap. Yes, that's 330,000uF! The bigger the cap the less likely to have a tiny fraction of a second glitch but when the problem happens it's a few-second loss of control that's irrecoverable before crashing. EEngineer specifically suggests not to use voltage protector with BX.

[wadders248]

Originally Posted by DoubleCH

I actually turned down the ESC beeps to 70 from default 100 and startup power from 1.00 to 0.25 on BLHeli. Even at 70, the beeps are pretty loud. And even at 0.125, motor spools up nicely but to be safe I set it to 0.25.

I tried the startup power at 0.125, though I don't think that was enough for the Scorpion motor as it wouldn't budge. The spool-up speed and power are just about perfect at 0.25

[DoubleCH]

Yeah, the 0.125 startup power setting was on the stock 300X motor which has pretty weak magnets and very little cogging. That motor will free-spin by the one-way bearing on spool-down!

[stevebaker]

I've read through EE's post. Some great info there.
I think you've cracked your problem and should be fine running an external BEC or using the Turnigy at 6V.
Some great info here for all those others on this forum having similar problems.

It looks like the combination of the stock ESC and the BX is marginally OK. I have got away with mine so far, but if I ever change out the cyclic servos I'll probably go ahead and change out my ESC like you have.

Thanks for taking the time to post all your findings
Steve

[sbarro]

Great thread, thanks for the info.
One thing I am puzzled about is you mentioned that you are running a redundant setup, i.e. pulling power from both the built in BEC and external SBEC?
I always understood that in order to run an external BEC, the built in one must be disabled by cutting the red wire.
Is that not correct?

[DoubleCH]

Yep, I thought about some potential adverse effect running 2 SBEC outputs together directly but after some testings I was willing to do that. That's after I've tried running just BEC from ESC and also just external BEC. I've tried a lot of different things. What I wasn't willing to try was to run 6V not knowing if all servos are good. Now that I've read that the cyclic servos are OK running 6V long term and just need to drop voltage for tail servo I have no problem running it that way. BX is not the only controller that can freak out if run below 6V. I read that 3GX really needs to run 6V or higher as well.

[stevebaker]

Rather than stepping down the voltage to the tail servo, I would change out the servo to a 'proper' 6V one that doesn't fail after 50 flights for no good reason.

The Hyperion DS11 GCB that I am using runs at 6V. It's cheap, fast, light weight, reliable and performs flawlessly on this heli.

I wish HH would make 'pro' versions of all these helis. where we pay more and don't have to change every single component

[SHYguy]

Couldn't find any specs for the stock E-Flite 300 or 450X ESCs. How many amps are the BECs in those?