6s set up in a Sebart 50e

[Dylan Reynolds LaserCraft Services]

Finally sorted a motor, esc and a ubec with fail safe for my Sebart 50e.

Spent the last 4 or 5 nights building and sorting out the innerds, bound it etc and the motor was running in reverse but otherwise fine, so switched 2 wires around to change the rotation, and on first fire up it did spin the correct way, but ever since that time it makes horrible grinding noises and attempts to spin in reverse again but not very well.

Also should the main battery be connected before or after the ubec battery? (never used a ubec before)

And finally is it normal to get a spark in the connectors when connecting a 6s battery? Never had one before in any other battery size, but these are my first 6s ones, so wondered if this was normal due to the power output of them.

Oh, one more thing, sorry, almost forgot, the spec for the equivalent Hacker motor (1280W 380kv) which is the recommended one suggests a 17x8 prop, whereas the motor I have installed (1350W 500KV) suggests prop sizes 15" and up, but I have to say the 17 actually looks too big for the airframe. I have not had a wattmeter on it yet due to the motor problem mentioned above.

[Allan Bennett]

"Grinding noises and attempts to spin in reverse..." can be an ESC timing issue, or a bad connection somewhere between motor and ESC. Whether you're using bullet connectors or have directly soldered the motor wires, you should check your solder joints.

In all my models I've got the stand-alone BEC permanently connected to the main battery leads, so that it gets its power the same time as the ESC does. If you have, and want to retain, a separate connection for the stand-alone BEC you should connect the BEC before you connect the ESC.

A spark is quite normal with a 6S battery pack; it's caused by the capacitors (the big round things) in the ESC charging up almost instantaneously when the battery is connected. With 6S I accept it, but in my 12S setups I've got a spark-eliminator. It's simply a resistor which is connected to the ESC's positive wire; the negative wire and this resistor are connected to the battery and a small current (because of the resistor) flows to charge up the capacitors in the ESC. After a couple of seconds, with the capacitors now fully charged, the main positive wire is connected up without any spark.

I would expect a higher kv motor to require a smaller prop for the same power output. But you really need a wattmeter on it to check that you're not exceeding the motor's amp rating, whatever prop you put on it.

[Dylan Reynolds LaserCraft Services]

cheers allan

just tried what you said and plugged ubec in first then main battery, but as soon as i touched the connectors i got a spark and 2 puffs of smoke, one from the receiver/ubec area and one fron the esc, the main battery wasnt connected at the time.

any ideas?

[Allan Bennett]

Good grief !!

So, you plugged the BEC into the receiver via its 3-wire lead and servo plug, then you connected the BEC's two battery wires to the main battery? That's the way it should work, with the BEC reducing the battery voltage down to a safe 5v (sometimes 6v) for the receiver and servos.

Sounds to me like the stand-alone BEC may have been faulty, and allowing full battery voltage to go straight through without reducing it down to 5v. Or, is there any chance you connected it to the battery the wrong way round? That could possibly fry some components and then allow full battery voltage through. What brand/model is it, and is it specced to handle the voltage of your main battery?

What were you using to power the receiver initially, when the motor spun okay but the wrong direction? If it was the BEC built into the ESC, you need to disconnect the ESC's red wire from its lead that goes to the receiver when you're using a stand-alone BEC (or receiver battery) for power. Many people say that leaving it connected will do no harm, but it's worth doing as a precaution in case the two different power sources interfere with, and damage, each other. Since you hadn't got the ESC powered-up at the time, I think this can be discounted as a possible source of the problem.

[Dylan Reynolds LaserCraft Services]

Hi again Allan

I plugged the ubec into receiver, I plugged the ubecs battery cable into a 2s battery (fail safe off of course), and as soon as the battery connectors touched, poof!

I then tried it esc battery to esc, then ubec battery to ubec and all was fine except the motor problem.

The red wire has been disconnected from the receiver wirre of the esc

The ubec is a dualsky VR-5L 5A linear voltage regulator input 6-10v (2s Li-XX), output 5-6v (adj upto 30w), reciever is a spectrum AR635, esc is an overlander XP-80A, motor is a thumper 4260.

Checked all wiring and they are all soldered to the correct terminals in the deans, so no cross polarity.

I have now gone over and over the setup reffering to the instructions with every component and I have to say I'm stumped, everything appears as it should. So I put it down to 2 possibilities, its either me (I have been known to missunderstand chinese sometimes) or there is a faulty item somewhere.

I am trying to upload some photos of the setup so you can see it.

But thank you Allan, its very reassuring to have someone to talk to about it even if we can't sort it out.

[Dylan Reynolds LaserCraft Services]

[Glyn R]

The wire from the Regulator is plugged in upside down with the positive to the signal. The other white wires are all signal. The red is power positive.

Edited By Glyn R on 06/05/2013 18:55:14

[Pete B]

That might just be the camera angle, Glyn - it's not possible to see if the red wire from the regulator is fitted to the signal or the positive pin.

Given that Dylan has disconnected the red wire from the ESC, I'll assume that he is aware that the centre pin is positive and wired correctly. The instructions mentions that the output is fitted with a JR connector, so should have been wired correctly in production.

Other than that, I still can't se anything obviously wrong. As Dean is using Deans () and few packs are supplied with such these days, the only wiring option left is that the battery pack Deans sockets may have been soldered in reverse.....a long shot, I know - but stranger things have happened!

Pete

[simon burch]

If you have seen a puff of smoke from anything electrical, it normally signals the end !! Might be worth leaving the esc and BEC disconnected and just power up the reciever with a normal rx pack just to check if you have damaged anything.

Regards,

Simon

[Allan Bennett]

Stranger things have happened -- I just went back to look at the photos a couple of times, and what I had written, but not yet posted, has disappeared

I'm just wondering if there's a 2-pin plug on the BEC output instead of 3-pin, then it would be possible to incorrectly connect it to the upper two pins instead of the lower two. This could also account for the different results when plugging it in different times -- i.e. sometimes it's inadvertently on the top two pins instead of the lower two out of three.

Also, is there a black wire plugged into the AUX1 channel, or is it a shadow?

There's no other logical reason I can think of why powering-up and plugging the BEC in before or after the ESC should have different outcomes. The reason for recommending BEC first is that it's good practice not to power up the ESC, and hence the motor circuit, without having a zero-throttle signal from the receiver. Obviously, if the receiver's not yet powered up, it can't give a zero-throttle signal.

Reversed red/black leads somewhere is an obvious possibility, except that things have worked okay sometimes, apart from the motor stuttering. But, as our Mod has said, it's not unknown for electronic items, or even the batteries themselves, to have their plugs and/or leads the wrong way round.

[Dylan Reynolds LaserCraft Services]

ok 3rd attempt at writing this after it vanished twice!

i'll keep it short, tired of losing the long version lol

yes, its an illusion, red is in centre pin and black on bottom, camera angle and thicker wires.

Aux 1 is a shadow

all deans correctly orientated

took it to the strip today for our leccy guru to give it the once over, gave it the thumbs up for installation, he then connected ubec battery, no smoke etc, connected main battery, no sparks, flicked failsafe switch and all come to life and bleeped as expected, all good so far. He tested servo operation and speedo, all worked no signs of anything being wrong.

We took it out onto the strip for him to test fly, and grin grind screetch and attempt to spin prop in reverse, hmmmm, try again, whizzz whheeerr, as it should be, strange he says, tries several more attempts and it working fine.

So he took it for a spin, everything was spot on, after a short trim flight, he landed, we swapped main battery to give it a good ringing out, he powered up, and again grind gring screetch, 2 or 3 times this happened, then it went normal again, tried several more times and he just couldn't get it to do it again, it just ran as smoothly as expected.

I then took it for a flight and the same thing happened again, then cleared

Just doesn't make sense, batteries have been swapped out several times now and everything on that side of things seems all normal, no damage showing from the previous puffs of smoke, just this motor problem

[John Olsen 1]

Could it be that the motor needs the timing adjusted on the ESC? This is not something I have ever had to do, the defaults have always worked for me, but if you check out most ESC instructions there is usually provision to adjust the timing.

John

[Glyn R]

Motor timing often causes a grinding on start up. Set it on high for a start.

[Allan Bennett]

+1 on the timing. Having said that, in the past I've had two ESCs that didn't like to "play" with their motors -- each time the ESC was the same brand as the motor it was supposed to be driving, and didn't have any timing adjustment. My only solution in each case was to go for a 3rd-party ESC.

As for the smoke, that's still a mystery, so you should still be cautious. One thing that could smoke, and not show any immediate effect, is the big capacitors at the end of your ESC and, possibly, your BEC too. They're there to protect the device from dangerous electrical "spikes" and, if they've been damaged, a more-critical component in the ESC or BEC may eventually fail. The spark you get when you initially connect the battery is caused by the capacitors taking a high momentary current to charge themselves up; if you observed no spark when you connected your battery at the field, that would seem to confirm they might be damaged.

[Ted]

If i am reading correctly I can only see a linear Voltage regulator which has a max voltage of 10 volts being cooked by a 6S Lipo. I use a voltage regulator with a 2S battery in place of a flight battery to run bench tests. But the LVR is discarded for a ubec wired into the main 5S battery for flight. Ted

[Allan Bennett]

Very good point Ted! I've read its spec now, and it's rated for 10v maximum -- 6S battery is 22v or thereabouts, no wonder something smoked, and surprising that things seem to be working for the moment.

Dylan, you must change that voltage regulator for one that's rated for 6S before you fly again, otherwise it's going to end in more tears. I use stand-alone BECs by Castle Creations, Hyperion, and Kool UBEC.

[Pete B]

Posted by Dylan Reynolds on 06/05/2013 10:33:46:

I plugged the ubec into receiver, I plugged the ubecs battery cable into a 2s battery (fail safe off of course), and as soon as the battery connectors touched, poof!

Dylan's already made it clear that he was using a 2s pack to power the regulator...

Having read the spec for the model, I think adding a second battery pack and regulator, rather than simply using a UBEC, has just complicated the issue and allowed more scope for problems, IMHO.

Of course, it's personal choice but I just don't see the need for it in a model of this size.

I use UBEC's on 4S to 6S models and they haven't given me any power supply issues at any time.

The motor turning problems are certainly symptomatic of a timing issue but that doesn't explain the smoke, so, all things considered, I'm still stumped - unless there was a fault in the v/r or switch mechanism.

Pete

Edited By Pete B - Moderator on 07/05/2013 12:38:02

Edited By Pete B - Moderator on 07/05/2013 13:04:16

[Dylan Reynolds LaserCraft Services]

Ok there seems to be some confusion on the actual setup so i'll give the run down again, just so we are all on the same page so to speak

The 6s is plugged into the esc, the esc into the motor and the receiver with the red wire removed from the reciever lead.

The the ubec/regulator is what my LMS suggested, this is connected to a 2s battery, a fail safe switch and the receiver. I was actually sold this as a ubec and not just a regulator, i asked for a suitable ubec and this is what they gave me and me not knowing any different used it as instructed.

The receiver itself is not connected to the 6s in anyway other than through the throttle lead which as menntioned has the red wire removed.

I will look into the timing setup issue and attempt to set it on high (as suggested) and see what happens.

The odd thing is I had this motor and esc setup in another model minus the ubec and never had a single problem with it..

I do appreciate all the replies of help, even if it is just confusing me even more as this is the first setup I have done myself rather than the usual bnf efforts i have used previously, certainly needs a lot more thinking about.

The plane has maidened and flies on rails, I never pushed the throttle above half mainly because of the problems, and landed well within 5 mins, didnt want to over do it to start with.

[Chris Bott - Moderator]

Dylan here's my 2p worth:-

Assuming you didn't make the thing smoke by connecting incorrectly, then I'd say the only reason for smoke to come out, would be that it was manufactured incorrectly, and the bit that was incorrect has been blown away. e.g. some types of capacitor will blow if they are connected the wrong way round, so maybe one had been inserted wrong. Same goes for things like a diode.

So maybe, you now have an ESC with a part missing. The part may even be there to ensure proper starting of the motor every time.

Of course this doesn't explain why you saw smoke from at least two different bits of gear.

[Allan Bennett]

Posted by Dylan Reynolds on 07/05/2013 17:37:07:

...The the ubec/regulator is what my LMS suggested, this is connected to a 2s battery, a fail safe switch and the receiver. I was actually sold this as a ubec and not just a regulator, i asked for a suitable ubec and this is what they gave me and me not knowing any different used it as instructed. ....

Sorry, I've got no further suggestions, though I do have a couple of comments: A "BEC" is a battery eliminator circuit, and it's supposed to allow you to eliminate the separate NiMh receiver battery when you've already got a big battery for your motor. It is, in fact, simply a voltage regulator, with its output voltage set at 5v, or maybe switchable between 5v and 6v. it can be incorporated into the ESC, or it can be stand-alone, as yours is. "UBEC" stands for universal BEC, and is the name give by Kool Flight Systems to their original switching BEC, but it's now used by many people as a generic term, like Hoover or Sellotape.

A linear BEC, like yours, reduces the voltage by converting the excess into heat. A switching BEC, on the other hand, reduces the effective output voltage by switching on and off many thousands of times per second. That produces much less heat, so allows switching BECs to be specified for higher voltage inputs and higher amp outputs.

The BEC setup your model shop has sold you is what glow modellers might use if they want to replace their NiMh receiver battery with a LiPo. In my opinion they shouldn't have sold you that if they knew you model was electric powered -- they should have sold you a switching BEC that can be powered directly from the 6S motor battery.  Personally I would advise you to cut your losses (or get the model shop to pay) and get a suitable one so that you can eliminate the separate 2S battery.

By the way, what is the "fail safe switch"?

Edited By Allan Bennett on 07/05/2013 19:35:16

[Dylan Reynolds LaserCraft Services]

The fail safe switch is incorporated into the linear BEC, dualskys words not mine, but it has a switch which cuts all signals to everything but keeping the receiver on and bound, so basically the motor or the flying surfaces will operate when you try from the trannie.

Understand now about the ubec system thank you very much for explainin it to me, at least i now know what i need

[Dylan Reynolds LaserCraft Services]

will not operate when ou try with your trannie i meant lol

[Allan Bennett]

I can't find anything about the "fail safe switch" in their blurb, and I'm highly sceptical that it'll work the way that's described, for only the receiver itself can supply the signals that switch things to their pre-determined fail-safe positions. And then, the receiver will only go to fail-safe it it loses radio signal but still has power.

What I read is that this BEC will simply stop supplying voltage to the receiver if it overheats, which will cause you to lose control of the model. But that's probably true of all BECs, whether they're stand-alone or built into the ESC, which is why you need to take care that your BEC has enough output capability when you're selecting.

[Dylan Reynolds LaserCraft Services]

On the packaging it is described as a fail safe switch, it is however in effect just a power switch, so when it is turned off it stops the 2s battery supplying power to the receiver, therefore stopping any signals to the control servos or throttle control, making the plane dead, even though the 6s is still connected to the esc, I agree, it isn't what I was expecting as a fail safe and would say it certainly isn't the correct terminology, but it is theirs, so I'll stick to it for the purposes of describing equipment and its specs. That said, this was sold to me by my LMS as a Ubec, which I'm not too happy about.

I hope this makes it a little clearer, as I don't want to come across as though i am doubting your knowledge in anyway, because I'm not, I am deeply endebted to you for your advice thus far, and looking forward to more, because this seems a lot steeper learning curve than I ever imagined.

Edited By Dylan Reynolds on 08/05/2013 17:18:13

[Allan Bennett]

Don't worry, I'm well aware that I haven't seen everything yet, and some kind of a failsafe might have been possible

As I think has been mentioned, that kind of BEC is often used by glow or petrol flyers who want to use a LiPo instead of a NiMh receiver battery. In that application the switch, provided it's on the battery input, is a good thing because it allows them to simply switch their receiver off after a flight.