Optipower BEC guard - do I need it for Kosmik?

[crash at 42]

Tom can the bec guard be used in conjunction with the r2 supercapacitor

[dl7uae]

Yes, of course, just connect to the output of the BG.
Same for the UG.

Things we design fit to each other of course.

[crash at 42]

Thanks your stuff rocks not sure everyone knows (EE) you and linus are the architects and backbone behind all this

[EEngineer]

r2 supercapacitor.....


What happens when the R2D2 is overvoltaged by non-brushed servo back EMF voltage spikes?


The caps are not rated to withstand such spikes.

[dl7uae]

What happens when the R2D2 is overvoltaged by non-brushed servo back EMF voltage spikes?
The caps are not rated to withstand such spikes.

Are you about to dismantle the "EEngineer" which you pretend to be?
Your question can not be serious, right?

[Pard]

Is there a problem, and if not, why not?

I understand that Western Robotics does not approve of the use of the BEC guard, ot capacitors in line with their products as well? Why?

Respectfully, I just wish to benefit from correct information, and am considering purchasing your products.

Thanks very much.

[dl7uae]

Ok.

First of all: We should avoid to mix up everything,
. voltage source Ultra Guard
. cap-based buffer
. protector BEC Guard

We also have to distinguish: Who is protected from whom, or who can be damaged by whom?

1. EMF kills R2 buffer caps? Caps (buffer) and voltage "spikes" by back EMF: Cap: Current comes before voltage. Those spikes are over before they can rise the voltage considerably. The caps "eat" the spikes.

2. BEC can kill R2 buffer? Supercap buffer standalone behind a BEC: In case the BEC gets defective and lets the raw voltage passing through the R2 buffer will probably be destroyed too (besides other electronics).
A BEC Guard between BEC and R2 buffer (all electronics) avoids that (overvoltage cut off).
Btw the BEC Guard also clamps the R/C voltage to a maximum of 10V, - see 1.

3. R2 buffer can kill a BEC? Yes, some BEC's are sensitive for getting voltage at the outlet which is higher than the current output voltage. External voltage is inevitably higher if the BEC is off for any reason.
The R2 anti-reversal option (R option for the R2 buffer) avoids that.
The BEC Guard avoids that.

3a. Other "dangerous" effects from a R2 buffer to a BEC? No. The maximum charge current is delimited and can be adjusted.

4. Can an Ultra Guard kill a BEC? Ultra Guard stepping in with a voltage 0.5V below the initially seen (measured/remembered) R/C voltage. This happens if the R/C voltage drops or the BEC shuts off. Same as 3. Some BEC's can be damaged by an external voltage been higher than the current output voltage (at least if no output) - eg Castle BEC and especially Western Robotics (+0.5V are already sufficient for a kill):
R2 buffer + R option: No reverse current, BEC protected.
R2 buffer or Ultra Guard or any buffer battery AND a BEC Guard between them and the BEC: BEC is protected from damage by an external voltage, every BEC!

So:
The BEC Guard (I intentionally do not use abbreviations as "BG" and "UG" anymore to avoid confusing of topics.) protects EVERY BEC from aspects that could be dangerous to a certain BEC. It also "cures" the R/C voltage in general and especially protects ALL electronics from every BEC.

WR: There must be some mistake. The BEC Guard cannot harm the Western Robotics BEC but an Ultra Guard w/o the BEC Guard could do (see 4.)

[Pard]

Thanks very much for the explanation.

[dl7uae]

[Vinger]

Will the BEC gaurd on its own between Kosmik and electronics times two for the master and slave cure the bootup problem with high power servos?

The reason for asking again is that you mentioned that the Ultra Gaurd will be supplying power to initialize the RX and hence the Kosmik.

[malc1]

I think that you will need an Ultra Guard with revised firmware to sort this.
Sounds like the same problem as I had.
I couldn't get my VBar with satellites to initialise correctly at all.

[dl7uae]

... You asked me that already and my answer was.
That has not changed during the last 2 days.

In most cases the powerup problem will be eliminated:
a) All voltage madness is locked out.
b) Because of the lockout the BEC will not have the additional problem with the load because it is disconnected by the BEC Guard during that short critical time.

Check the image again and watch the "goodie effect" by disconnected load (red circles):



If the BEC voltage nevertheless drops again below 3V then the BEC Guard cannot help either.

Some setups suffer from contact and line resistance in relation to current drawn by extremist servos. They suffer also from supplied devices which are very sensitive to voltage drops (above all: SPEKTRUM Sat).
To buffer these problems away because nobody can cure it with today's servo connectors, to avoid that a SPEKTRUM sat starts undervoltage blinking already at startup, - we developed a still "experimental" (not deployed yet) change of the firmware for the Ultra Guard. With this firmware the UG acts as a normal "battery" during powerup, measuring the nominal R/C voltage a bit later, and afterwards acting as dynamically fast stepping in buffer in the known manner of an UG.

experimental/not deployed yet: If somebody wants to have the firmware right now: just PM to Linus. (your Ultra Guard needs to have an USB connector)

[Pard]

O.K. I am sold, just ordered the supercombo from experience RC. I plan to test with Vbar Control and many different servo and BEC combos.
Vbar control is the best I can do without having a scope, but at least I get real time telemetry voltage info. The dreaded 3.3 rail low voltage warning is like the sound barrier before the X-1.

Jazz 40 Internal BEC
HobbyWing 50 Internal BEC
Castle Talon Internal BEC

CC 10Amp BEC and Super BEC
WR High Volatge BEC
WR mini super BEC
Gryphon Polaris BEC
MTTEC Keto BEC

BK and KST mini and midsize servos.

Thanks.

[dl7uae]

Jazz 40 Internal BEC

OMG!
Weak buck converter with an undersized SMD inductance. Good for no more than 1.5A. Avoid short circuit, the SMD inductor often blows.

[Pard]

Originally Posted by dl7uae

OMG!
Weak buck converter with an undersized SMD inductance. Good for no more than 1.5A. Avoid short circuit, the SMD inductor often blows.

Thats what she said

[crash at 42]

So I recieved and installed 2 BG today and the low voltage problem still exists

[dl7uae]

What is your telemetry?

The plus wire in JLog's harness to KOSMIK is still connected?

If this is the case then there is the chance to build a voltage bypass around the BEC Guard which would make the voltage lockout of the BEC Guard ineffective.

The chance exists if your telemetry is Futaba s.bus2 or Frsky s.port. At the center pin of JLog's corresponding pin +3.3V output voltage of its internal voltage regulator coming out.
It's required to remove the red wire from the servo cable JLog/s.bus2,s.port --> receiver! Otherwise the bypass is: KOSMIK/JIVEpro-OPTions-port --> JLog "KOSMIK port" --> internal voltage regulator 3.3V --> JLog's s.bus2/s.port --> receiver etc.

[crash at 42]

No telemetry, yet efuel gauge planned. Currently Kosmik with 2xs BG direct to fbl, super caps direct to Sbus receiver.

[dl7uae]

I need to know all wiring details.

Wiring like this (attachment)?

[crash at 42]

Tom exactly like the pic without Jlog
2xs BG in line to fbl
futaba rx sbus
I've installed efuel gauge connected to Sbus2 rx but fluctuations exist. Once the super caps reach sustainable charge (+5.5 about 1 minute) the fbl unit itializes and subsequently the kosmik.