Optipower BEC guard - do I need it for Kosmik?

[Pard]

Just an FYI for Optiguard users:

From Me to optiguard:

I have an optipower ultraguard installed on my Trex 500 with full size Vbar. Great product .

I noticed that when the heli is not powered up, (no battery going through the BEC, and the ultra guard is off) if I move the servos, such as when folding the blades to put them in the holders after the day is done, the Ultraguard will flash the white warning LEDs and the red led will blink for a few seconds then go dark again.

Is this normal?


From OptiGuard:

Perfectly normal' the IG430 reacts to sensed volts when you move the servos manually they become electric generators in fact they can produce very high bolts 30v+ is possible on dome hence the introduction of the BEC Guard to stop back EMF at these higher levels.

The UG430 sence the volts as they are >4V and starts to arm but the time is too short to actually arm, it's doing what it is programmed to do.

No damage done unless very prolonged which is rare. Got a BEC Guard and you are fully safe!

[dl7uae]

Yep, that's normal.

It is not that the microcontroller (MCU) is running all the time (draws too much current). The only device being "active" in off mode is the enabling logic of a voltage regulator (LDO). Generative voltage ("back EMF") may enable the LDO. Because there is not enough and no stable voltage from the R/C power line the LDO gets the raw voltage from the LiPo. MCU gets supply voltage, awakes and checks the voltage situation. It signals its awakening by a LED flash. Voltage check by processor shows that there is no reason to continue processing, so it switches its own supply voltage off by disabling the LDO again (suicide).

----------

Pl8 supports charge thru balance leads only. He should be able to get it to work.

Hmm.. Then this is weird..

[PHANTMXR6]

Nope. Nothing weird here guys. Got it sorted.
I can't charge through the balance leads as I don't have an FMA balance board to support it.

I will have to order the correct balance board from Revolectrix to allow me to do so.

[Grittner]

..

[EEngineer]

Originally Posted by Wh1teAfr1can

the fuse is based on these approximate values


(table credit to AndrewJHawes)
Time Characteristic
% of Amp Rating - Opening Time (Minimum / Maximum)
110% - (100 hrs / )
135% - (90 sec / 3600 sec)
200% - (3 sec / 100 sec)
350% - (0.3 sec / 3 sec)
600% - (0.1 sec / 1 sec)


so using the above table with a 200 amp fuse you have around 2.5 seconds at ~430 amps having a "spike" that lasts for more than 2 seconds is almost impossible.

The fuse is a "Little Fuse" and it's specs can be found at


http://www.littelfuse.com/


Littlefuse has already characterized their fuses.

[EEngineer]

voltage regulator (LDO).


An LDO regulator had nothing to do with an SBEC....it's just a linear regulator which is inefficient when the differential between the input and output voltage is large.

[EEngineer]

"The caps "eat" the spikes."


No, that's not the way it works.


Caps are used to provide backup for current surges.....and not to suppress voltage spikes.


Diodes are used to suppress voltage spikes....like in an ESC's "freewheeling" circuits.

[dl7uae]

You seem to be a "DC electronics".