Brown out with Koby 40 ESC on the bench

[NewR]

Originally Posted by Jeff_Barrett

I'm stocking and using this one as it's rated for 10A (20A peak):
http://www.western-robotics.com/herc...r-mini_hp.html

That is crazy! (not you by any mean ) that we have to consider using that BEC on a 450 size heli.

I am starting to regret getting the 92A+. Luckily I did not order a 2nd set for the stretched Mini P.

[Stevemech]

There's alot of cyclic travel and the swash is more 500 size while using smallest servos.If the Kst ds215 servos where more reliable they would probably work awesome(3.7 torque at7v).You need to make everything bind free !
Steve

[Rob43]

Originally Posted by kalleh

Hence my disclaimer in the last sentence of my post The test does not answer "Will the MKS servos make the sats reset in flight with the Koby 40 BEC?". It answers "Can the MKS servos generate more current draw than the Koby 40 BEC can handle?". The answer to the first question is "anecdotal evidence says no, but it seems to be pretty close". The answer to the second question is "YES".

Point taken, kalleh!

I was also thinking of Dave Ketelhut flying the Koby 55 with MKS servos and without the issue as well.

I ordered my second Fromeco DC-UP MkII for mine. If it's only the periodic peak load scenario, the DC-UP is an effective solution. Massive capacitance without the weight. 1.2 FARADS. Not millifarads, but FARADS. Will prevent reset, enhance the servo performance, and not need a parallel power connection. Also, is small enough to mount on the side of the frame at a weight penalty of only 17g. 25mm x 69mm dimension. Plug into extra port on FBL unit or rx. Two seasons of flight on my 7HV without incident. Jive BEC, 8717's, and 2300 rpm there on a 5.2kg model.

[Jason O'Connell]

Originally Posted by Rob43

Point taken, kalleh!

I was also thinking of Dave Ketelhut flying the Koby 55 with MKS servos and without the issue as well.

I ordered my second Fromeco DC-UP MkII for mine. If it's only the periodic peak load scenario, the DC-UP is an effective solution. Massive capacitance without the weight. 1.2 FARADS. Not millifarads, but FARADS. Will prevent reset, enhance the servo performance, and not need a parallel power connection. Also, is small enough to mount on the side of the frame at a weight penalty of only 17g. 25mm x 69mm dimension. Plug into extra port on FBL unit or rx. Two seasons of flight on my 7HV without incident. Jive BEC, 8717's, and 2300 rpm there on a 5.2kg model.

Great! I like that way more than a buffer pack.

Ordered.

[desertstalker]

Originally Posted by kalleh

Hence my disclaimer in the last sentence of my post The test does not answer "Will the MKS servos make the sats reset in flight with the Koby 40 BEC?". It answers "Can the MKS servos generate more current draw than the Koby 40 BEC can handle?". The answer to the first question is "anecdotal evidence says no, but it seems to be pretty close". The answer to the second question is "YES".

The fact one person can force a reset does not indicate everyone should abandon the ESC's BEC (their unit may not be operating to spec).

I run DS95s and a 95i in my stretch mini P on a YGE 3/5A BEC (MSH standard YGE 60A). and the voltage is pretty stable (SK Log and spec telemetry). I only had issues with voltage dips trying to run 3 Hyp DS16s and a BLS251 on a protos but they were still short of dangerous (tripping alarm at 4.5V).

Many people have flown hundreds of flights on MKS micro servos with BECs of similar or less capacity than the one on the Koby, I have not heard of many problem reports.

[kalleh]

Originally Posted by desertstalker

The fact one person can force a reset does not indicate everyone should abandon the ESC's BEC (their unit may not be operating to spec).

I run DS95s and a 95i in my stretch mini P on a YGE 3/5A BEC (MSH standard YGE 60A). and the voltage is pretty stable (SK Log and spec telemetry). I only had issues with voltage dips trying to run 3 Hyp DS16s and a BLS251 on a protos but they were still short of dangerous (tripping alarm at 4.5V).

Many people have flown hundreds of flights on MKS micro servos with BECs of similar or less capacity than the one on the Koby, I have not heard of many problem reports.

Oh so true! I think my followup was a bit over ambitious. Everyone should try this on their own setup (it's easy!) and depending on the results make their own conclusions.

[Lompma]

I just tried to recreate a brown out condition with the same technique as the OP. I have the Koby 55 with MKS95 cyc and MKS95i tail. I tried multiple times to get a bench brown out and it just didnt happen. This is on a 4S Mini.

[r1sportbike]

Originally Posted by ScotY

Spektrum or Futaba?

And what servos?

Futaba S-Bus, VBar and MKS 92a+ and 8910a

[Rob43]

I don't know for sure I will need the DC-UP, but it can be used as an insurance policy on this model, or my 6HV, and for $35, I felt it's a reasonable cost measure to have in my stash. I can try the same test as kalleh and see if mine does this before trying to fit the device and see if I think it is needed. Unfortunately, I don't know if I have a good way of measuring the BEC amp output, like I can with my Jives using Jlog2.

[ScotY]

Originally Posted by Lompma

I just tried to recreate a brown out condition with the same technique as the OP. I have the Koby 55 with MKS95 cyc and MKS95i tail. I tried multiple times to get a bench brown out and it just didnt happen. This is on a 4S Mini.

Are you using Spektrum?

[ScotY]

Originally Posted by r1sportbike

Futaba S-Bus, VBar and MKS 92a+ and 8910a

So could this BEC issue be limited to Spektrum users?

[kalleh]

Originally Posted by ScotY

So could this BEC issue be limited to Spektrum users?

Hmm, just noticed that Captron states that the minimum voltage *when using spectrum sats* is 5.5V. This requirement is specific to spektrum.

What is the default BEC voltage on the Koby 40?

[esmoglo]

The output voltage of the synchronized BEC is adjustable from 5.6 V to 8 V. This allows for powerful supply of servos of the latest generation. So I guess if you want to set it to 6V you need a prog disk? Or one of the prog cards? Anyone on this?

[Lompma]

Originally Posted by ScotY

Are you using Spektrum?

Yes Spektrum sats. Could be 92A's vs. the 95's

[esmoglo]

Per the manual:

For BEC voltages exceeding 5.6V a redundant
receiver current supply should be connected.
Using this ESC without BEC is possible by pulling
the red strand off the connector or by ripping this

cable.

Also:

The BEC-Voltage can
be changed between 5V and 8V (0.2V steps) by

using PROGDISC...

So the card is not an option then

So if Sepktrum needs 5.5V you have a big .01V to play with I can see a brown out happening easily.

[ccnada]

Originally Posted by Jeff_Barrett

I'm stocking and using this one as it's rated for 10A (20A peak):
http://www.western-robotics.com/herc...r-mini_hp.html

That is what I'm running and it gives me alot of peace of mind. Plus I wouldn't run the internal BEC from my Hobbywing.

[kalleh]

Originally Posted by esmoglo

Per the manual:

For BEC voltages exceeding 5.6V a redundant
receiver current supply should be connected.
Using this ESC without BEC is possible by pulling
the red strand off the connector or by ripping this

cable.

Also:

The BEC-Voltage can
be changed between 5V and 8V (0.2V steps) by

using PROGDISC...

So the card is not an option then

So if Sepktrum needs 5.5V you have a big .01V to play with I can see a brown out happening easily.

Note that the 5.5V requirement might might be specific to the HC3-SX unit and how it distributes power to the sats.

[itsmillertime0]

I'm using a CC lite 50 with voltage output set to 6.0 and I can still brown out my sat receiver

[esmoglo]

So I guess I will just get the WR Bec then why on earth I spent so much on the Koby is beyond me not to mention that you need a $129 dollar Prog disk to program it (load of BS). I should have gone with the YEG 40 and a WR Bec I would have saved a few $$ VS buying the Koby.

[John Cook]

I'd say it's more of a spektrum issue.

I have an older jazz 40, and I"m using the bec with MKS92 A+ servos cyclic and 95i tail. No issues at least until I crashed it. I fly futaba and even use the 6203SBE which is a park flier rx ie stubby little antennae.

btw I don't think this is a "problem" re: the MKS 92A+/95 cyclic servos. But I think we need to understand they/MKS did put in a significantly bigger motor than a "normal" micro size servo would run, plus it's coreless vs cored motor, which I think will allow it to draw more juice as well. So inherent to the performance of the motor/servo it's going to draw more amperage than say a Hitech 5065.

I really doubt that current draws are consistently more than 1-2 amps for the electronics(servos, rx, etc..), with spikes obviously higher than that, but my point is I don't think we've exceeded the limits of the BEC persay. Now there may be some BEC's that aren't up to spec(poor design, old components, failing, crash damage etc..), or some setups, or other components that are causing over amperage conditions.

I do recall though I did have a rx reset in flight with Futaba on my 450 pro and D95 servos using the Align esc. Once I moved to the ICE in that machine all problems were moot. Also, that heli with the Align esc I don't think it was the BEC at fault but me running the stock ESC too hard and got hot and then the BEC suffered due to that. If you are getting a HOT esc and approaching limits of the ESC side, the BEC could suffer from the temps(increased resistence). Now the bench testing some are doing won't account for a hot ESC as it should be cool given the bench setup, but just throwing that out there to think about too.