First time builder looking for wiring advice, BEC to Gpro

[Euclid]

I'm building my first heli, a Trex 450l 6S, everything so far has gone great despite (or because of) Align's manual! I've have learnt a lot about the heli from the build experience, much much more than if I'd have just bought and flown a ready made model.

My next step is wiring and here the manual has let me down and I can't find the answer searching the net.

I'd like to confirm that the signal output from the BEC (Align RCE-BL45X) plugs directly into the THR port on the Gpro and I can ignore the BATT connections at the bottom of the GPro? This being the case I'm guessing the Gpro and servos get their power from the Red and Black leads on the cable and the BEC gets the motor speed signal from the white lead.

i appreciate this might be a bone beginner's question but wanted to check before I get an escape of magic smoke from either the BEC or Gpro.

[DaveG]

Your right in your thinking, the Gpro will draw power from the THR connection from the BEC of the ESC and feed it to the powerbus of the Gpro to all other channels.

Dave

[myxiplx]

Yup, you're understanding it correctly. All the servo and throttle wires on any FBL unit share a common power bus, so you can actually feed power in to any of them via the red and black wires.

The BATT port is for use when you have say a nitro helicopter with a throttle servo, and need a separate port to feed in power.

On larger helicopters and high end BECs you'll often get two power leads, one which you connect to the THR port, and then a second lead that goes to the BATT port and gives you a backup lead as well as more current to the FBL.

[Euclid]

Thanks for your answers Gents, there is something to be said for having such a poor Instruction Manual. It makes you question why you are doing something as well as what you are doing.

[Euclid]

Next question if I may? Having found a local(ish) hobby shop that sells Deans' connectors I've now managed to power up the Gpro and bind it to my transmitter. The spark I pulled when I connected to the 6S to the BEC/ESC gave me a bit of a surprise and the question is, 'Is pulling a spark normal every time the battery is connected?'

Years ago I promised myself a decent soldering iron but never got around to it, oh how I'm regretting that now! My £10 Aldi/Lidl special managed the Deans' connectors but what a struggle.

[Granpappy]

My 6S pack sparks every time I connect it. It also gives off a slight 'crack' noise. It's never done any harm and I assume it's normal.

You need to make sure that you've soldered the deans connector on properly. If you are using a low wattage iron then it might not have done a good job even if you get an electrical connection.

I use a 100 watt iron which is about £16 from Maplin. I wouldn't trust a low wattage iron to do the job because it won't be long before the connection fails and it all ends in tears.

[Euclid]

Thanks for the reassurance Graham, not quite the behaviour I was expecting from a low voltage circuit but happy to know it's not just me. What I'd really like is one of the high end soldering stations I've used in anger at work over the years but investing 3 or 4 figures in one is not going to happen. I guess a trip to Maplin is on the cards.

[Granpappy]

Thanks for the reassurance Graham, not quite the behaviour I was expecting from a low voltage circuit but happy to know it's not just me.

No worries. It's not really low power. 6S is 25 volts with lots of amps when fully charged. A 12 volt car battery will crack a bit. A 25 volt Lipo battery will crack a bit more. They might be small but there is a lot of energy there.

[tourerjim]

Thanks for your answers Gents, there is something to be said for having such a poor Instruction Manual. It makes you question why you are doing something as well as what you are doing.

Crap is more the word i would use.

[Euclid]

No argument from me with that description.

[myxiplx]

Yeah, the spark is normal, there's a ton of current as you first connect a lot of ESCs as it feeds straight to the capacitors. You can buy anti-spark circuits (although I wouldn't bother as people get hundreds and hundreds of flights without), and some ESCs include anti-spark features.

Just be aware that with a spark you might want to think about changing the connectors after 500 flights or so, just keep an eye on them as they will eventually pit and wear out.

And a decent soldering iron is a worthwhile investment, there's a reasonable amount to solder in this hobby, and when you have hundreds or thousands of pounds of kit in the air vibrating like crazy you really need to be able to trust your joints! It sounds like you know soldering though, so you may be able to get away with a cheap iron, but you can pick up a budget soldering station for not much money and it's probably worth it.

[Euclid]

During my early working life I'd have my head in a cloud of solder/flux fumes at least once a day. Those were the times of thermionic valves and components big enough to see and pick-up. Thankfully as things got smaller, the wattage requirement reduced and my eyesight got worse my times on the bench got less. I'm already looking around the web to find something suitable and will consign my Aldi/Lidl special to the bin. Somehow I think my other iron, a fine point 25w jobbie, isn't going to cope.