What is this for?

[alistair.howie]

I just took delivery of a Scorpion 50V 90A ESC.

Coming off the red power lead, half way up, is a loop of separate red wire which has been afixed with heatshrink (presumably covering a solder joint).

What is this wire for??

Thanks

Alistair

[millerman]

You disconnect it when connecting your batts and reconnect it once
You have done so , it's to stop the sparking poping noise ( don't know the technical term )


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[Mark_T]

I know you know what you mean Millerman, but just for the OP, the loop of wire is not the bit that is disconnected but on the main, thick, wire there is a large bullet connector in-between the two ends of the loop.

It will be obvious when you look closely, but you disconnect the thick wire so it just leaves the thin wire connecting everything together. Do this before you connect the battery then wait a few seconds while the ESC arms then connect the main wire again.

This sort of anti-spark set-up as standard is a nice addition.

[horsham rc]

Opto

[alistair.howie]

OK, that's good to know - thank you! That was the starter for 10, now three follow-ups, if you don't mind!

1) The anti spark feature has nothing to do with it being opto, does it? Opto keeps the signal side separate from the power side, right? Does the loop of wire have anything to do with that?

2) I need to fit a CC BEC pro to the power wires. Does it matter whether than is attached "upstream" between the loop and the esc, or "downstream" after the loop and before the battery connector (am using Anderson PowerPoles, so the combined thickness of the two wires is too much for the APP connectors

3) Just a though re the Opto feature, if I am using a BEC to power the receiver, does that negate the benefits of Opto because it makes a direct link between the battery and the receiver? I'm getting confused here. Should I just use a standalone battery pack (am flying a 550e with minivbar) or is that overkill?

Thanks again.

[millerman]

1) no
2) not tried it as i run it 12s and use an external reciever pack as i run a HV setup (sorry)
3) if your running 610's and a 620 you can use them 2s lipo or run a small li-fe pack far more reliable than any bec (my personal opinion)

[Mark_T]

... or run a small li-fe pack far more reliable than any bec (my personal opinion)

I tend to agree.

I'd much rather find the space for the LiFe pack than fit a BEC and associated wiring. This also makes it easier to turn on the receiver and servos for bench testing without having to connect the main power pack and have the motor live.

[alistair.howie]

Kel/Mark

Do you suggest that I run LiFE unregulated on Align 610 and 650 servos (actually the Savox equivalent but I can't remember the servo names/numbers). Rated to 6V only. If yes, what sort of capacity and how many flights (approx) would I get out of one charge on a 550e with mini vbar? If not, what step down regulator do I use? I have a CC BEC Pro, but am wanting to eliminate as much wiring as possible. Is there a simpler piece of kit than a BEC that is pretty much bullet/fail proof?

Newbie questions ... sorry!

[Gareth-71]

Hi

I run BEC on all of my heli's - some disasters over the years, but have it down to a fine art, so:

1. No
2. Even though the BEC Pro states 12s, don't! Use it as 6S. So the black wire from the BEC goes to the black wire on the ESC, the red wire from the bec goes to the 'LOOP' - the wire that joins the two packs. In this config the BEC PRo V2 has proven faultless.
3. No, it does not negate the Opto, its all to do with power paths and ground loops.

:-)

Gareth

[Mark_T]

Do you suggest that I run LiFE unregulated on Align 610 and 650 servos (actually the Savox equivalent but I can't remember the servo names/numbers). Rated to 6V only. If yes, what sort of capacity and how many flights (approx) would I get out of one charge on a 550e with mini vbar?

I wouldn't have any concerns about running servos rated at 6V on an unregulated LiFe pack.

Remember a '6V' rating means it is safe to use on a 5 cell NiCad pack which would be giving you around 6.5V under load when freshly charged, the LiFe pack is going to be giving you around 6.3V under load.

Hard to be precise about how many flights you'll get as the answer depends on how you fly and how big the LiFe pack is. The size (capacity) of the pack depends on how much space you have for it and how the weight affects the CoG.

I have seen people using 2000 - 3000 mAh packs reporting 5+ flights on similarly spec'd 550's but you must be very careful when you first use your LiFe pack to learn just how much you are taking out of it as you can't measure the remaining capacity or even estimate it as you would with a LiPo by checking cell voltage.

Best approach is to do a couple of flights then recharge it and note how much goes back in, that way you'll get an estimate for the safe number of flights you can do. Always err on the side of caution as a LiFe pack will go from working perfectly to dead in a very short space of time if you push it too far.

[scallybert]

Hard to be precise about how many flights you'll get as the answer depends on how you fly and how big the LiFe pack is. The size (capacity) of the pack depends on how much space you have for it and how the weight affects the CoG.

Which is a fairly good argument for using a BEC from the motor pack...

[Not necessarilly an overwhelming argument, though...]

[alistair.howie]

Yup - am coming full circle with my thinking here.

On a related point, why does the Trex 550e come with a BEC equipped ESC as standard, but for the 600 you're expected to use a separate receiver battery. What's the difference?

[Mark_T]

Which is a fairly good argument for using a BEC from the motor pack...

[Not necessarilly an overwhelming argument, though...]

Lots of pros and cons as ever

Main issue for me with a BEC running off the flight pack is if the flight pack fails or the BEC fails the heli is going down without control. Most BECs have pretty limited ability to supply current, only takes a couple of stalled servos for a little too long and you may overload it, much harder to do that with a straight feed from a battery.

In the end though the choices are ours to make and there is nothing wrong with a little diversity.