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Author Topic: Why do I ever get 'normal' problems? Help please  (Read 7182 times)

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Why do I ever get 'normal' problems? Help please
« on: March 25, 2016, 09:04:58 pm »

today I set up my 4 servo winches. Each one works fine, unfortunately they only work fine when plugged in individually. Plugging a second one in at the same time results in the receiver light switching from green to red and back again whilst the servo slowly turns.


 I suspect it may be that the battery packs need a better charge even though they are above 6v. They are Turnigy 6v LSD 2300 mah. I am running the servos through a UBEC but I don't know if the jumper switch is on 6v or 4.8 (I'll have to dig out the destructions.)


Now it's just an idea by someone who lacks knowledge of electrics but if I was to join the batteries in series making it a 12v pack (if possible) and then run it through a 6v BEC would this be better than running 1x6v pack through a 6v BEC and risking going below 6v and therefore not having the voltage to work it correctly.
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inertia

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Re: Why do I ever get 'normal' problems? Help please
« Reply #1 on: March 25, 2016, 11:09:48 pm »

You need a battery of at least 0.5v higher than the required output for a UBEC to work.
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Re: Why do I ever get 'normal' problems? Help please
« Reply #2 on: March 26, 2016, 06:26:28 am »

Thank you Inertia I assumed it may be something like that.


About the joining of the packs, is it a reasonable idea or is it ridiculous? My reasoning is that my Battery pack is 6v (which charges to over 7or 8v) and it settles quickly back down to 6v. If my UBEC needs 0.5v higher then maybe my problem is lack of power even with a reasonably charged pack. I have a battery tray for the shape of the pack and if I can get away with not ordering a bigger battery then all the better.


Any help appreciated.   U2

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Umi_Ryuzuki

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Re: Why do I ever get 'normal' problems? Help please
« Reply #3 on: March 26, 2016, 06:44:51 am »

I think the problem may be that the BEC is not providing enough amperage to your
reciever and servos. A BEC that will provide 6 volts, and 3amp to 5amps may be required.
Check for a company that provides stand alone BEC, or try hooking a six volt battery directly
to your receiver via the BATT connection on your receiver and see if providing a dedicated
receiver battery solves the problem.


 :-)

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Re: Why do I never get 'normal' problems? Help please
« Reply #4 on: March 26, 2016, 01:02:18 pm »

Whoopee I've managed to sort an electrical problem and all four winch servos now work :} :} :} :}


I decided to join two receiver packs in series giving me 12v. This then runs through the same stand alone BEC as before but with the extra voltage it mustn't now dip below the minimum requirement needed to power everything. OR as Ryumi stated it must now have more amps.


I'm really happy............
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inertia

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Re: Why do I ever get 'normal' problems? Help please
« Reply #5 on: March 26, 2016, 02:54:02 pm »

A BEC has what's called a drop-out voltage, which is the minimum difference between the input and output voltages required to overcome the internal resistance of the regulator. This is usually of the order of 0.5v. A nominal 6v battery will only exceed 6.5v when freshly charged, so under load your BEC was not being supplied with enough volts to provide your receiver and whatever else you have connected. You'll probably now find that the BEC gets a lot warmer with a 12v input, but I'm still at a loss to understand why you want to connect 2 x 6v batteries in series to give 12v and then drop it back down to 6v again. As Ami says, a simple connection of one 6v battery to the receiver would do the same thing and do away with the BEC.

I would be tempted to power the winch servos from their own separate battery pack and by-pass the receiver; the circuit is easy enough.

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Re: Why do I ever get 'normal' problems? Help please
« Reply #6 on: March 26, 2016, 05:00:55 pm »

If a casual observer gets the feeling they are missing half the story, chapter 1 is entitled "Will this work?" http://www.modelboatmayhem.co.uk/forum/index.php?topic=53875
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inertia

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Re: Why do I ever get 'normal' problems? Help please
« Reply #7 on: March 26, 2016, 06:45:38 pm »

Thanks for the reminder, Mike. I thought I'd had this particular headache before...
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malcolmfrary

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Re: Why do I ever get 'normal' problems? Help please
« Reply #8 on: March 26, 2016, 07:36:26 pm »

Most BECs act like a self adjusting resistor, adjusting themselves to be the exact right value to give the required voltage according to the load presented.  But within limits.  Too much load or not enough starting voltage, the required voltage cannot be maintained.  Too much starting voltage and too much current demanded results in the BEC protesting, by getting very hot, then signalling that it has died by letting the magic smoke out.
A µBEC, on the other hand, is a device that switches very rapidly with the switching self adjusting to give the required voltage out.  Operated within its design limits, it can handle more volts in and at a higher current without getting hot.
Upping the input voltage to give the setup enough volts out at the current wanted is probably not going to be a long lasting solution with a "normal" BEC.
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Re: Why do I ever get 'normal' problems? Help please
« Reply #9 on: March 26, 2016, 10:12:23 pm »

Microgyros


You are correct, I'm guilty as charged (Ho Ho).


After reading through the other thread I think I owe some explanations, after all you guys and gals did help me.


my knowledge of electrics is second to none, ie just below none.....

[size=78%] I [/size]
wanted 6v of power to give maximum torque to my 4 winch servos (not 4.8v)[size=78%]


my receiver takes up to 6v input


a fully charged receiver pack can go above 6v so therefore it's best to have a stand alone BEC to regulate the voltage and not exceed the 6v.


the BEC needs to be 0.5v above the dropout voltage (just quoting what I've read, I don't claim to have understood this at the time) so by adding two packs in series I get 12v dropped to exactly 6v by the BEC and enough power for long enough to power all my winches. It works!


If I plug my 6v pack straight into my receiver it's above 7.5v when fully charged and could blow something hence the need for a stand alone BEC.


With a stand alone BEC I need more than 6.5v so that's why I wanted 2x 6v packs which give 12v and is subsequently dropped back to 6v. WHY didn't I just buy a 7.2 or 8.4v pack? WELL firstly I didn't know if that would fix my problem, secondly I have a battery tray made to fit the packs and thirdly I have 2 packs here ready to fit instead of paying money for a new battery and then waiting and having to build a new battery box.


I wanted a second indipendent battery to power an ESC and motor in case of emergency.


I wanted this battery to stay inside the boat as long as possible without the need to charge it. It had to be powerful enough to power the brushless motor (11 to 18v) So it had to be a lipo and on a system that was not draining even a tiny bit of power until a switch was flicked.


Why a lipo I can hear? They hold charge and they are lightweight and they have the discharge capability to power a brushless motor.


I thank all you guys for trying to help me and I apologise for the headaches  :embarrassed:  BUT what is obvious to you guys is sometimes very confusing for people with no understanding of electrics.


Nowhere on my BEC instructions does it say 'when supplying 6v from this BEC you will need more than 6.5v  or it will stop working and only maybe power 1 servo. It does however state that it works from 4.8v up to 26v. Now I've seen a device which plugs into a 12v cigarette lighter in a car and changes it into enough volts to power a telly and thought maybe a BEC works similar to that


Now it's me who's at a loss because I can't understand why anyone would plug a fully charged 6v pack (possibly charged to 7.5 v) into a receiver that could blow if over 6v is plugged into it.


BUT at the end of the day I'm still happy, very glad of all your help and still learning 'the black arts'


Now if any of you guys need any help building I'll be only too glad to help...... Thanks again, until my next electrical problem......... A happy U2 :} :} :} :}
[/size]
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Re: Why do I ever get 'normal' problems? Help please
« Reply #10 on: March 26, 2016, 10:28:21 pm »

Hi Malcolm. I had to google the difference between BEC and UBEC and I could only find that the 'U' on UBEC meant 'ultimate' and was just a gimmick to help sales. (Please correct me if I'm wrong I wouldn't know other than looking on google for stuff I have no knowledge of)


I couldn't find the difference between BEC and 'normal BEC' how can I tell if my BEC is normal or not?


All I can say with confidence is that the number of volts going into the BEC is about 2/3rds of what its maximum is and it works fine and I'm happy and thank all you guys who have helped me........ U2



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Umi_Ryuzuki

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Re: Why do I ever get 'normal' problems? Help please
« Reply #11 on: March 26, 2016, 11:34:38 pm »

There is a slight difference between U, and u and μ.
The first two being the upper and lower case of the letter "U".
The latter being the symbol "Mu" or μ. It is often used to represent the word "Micro".


In the case of μBEC, it sometimes means "stand alone BEC"
A stand alone BEC is often rated to convert higher voltages to power your receiver and servos.
They also are often set up to provide higher amperage through the system.
Most standard BEC on speed controls will supply 500mah to 1000mah.
Stand alone BEC are often designed to be more efficient using a switching circuit to
avoid burning off extra voltage as heat, and will also supply 3000mah - 5000mah through the cirucuit.


Also the suggestion for running power directly to the winches and plugging only the signal wire
to the receiver is another good way to run high power servo without drawing that power through
the more sensitive receiver.


 :-))

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Re: Why do I ever get 'normal' problems? Help please
« Reply #12 on: March 27, 2016, 08:44:20 am »

Umi, thank you very much for taking the time to explain in terms I can begin to understand (I don't claim it will all stay in small allocated space in my brain labelled 'electrical knowledge' but I'm sure some will stay there)


So, I imagine that my original setup of four winches going through a 'normal' BEC, ie a BEC inside an ESC was only providing 500 to 1000mah. This meant not enough power was being provided to power them all and subsequently only 1 servo would work and plugging in a second servo caused too much electrical draw and resulted in 'a problem'
Someone suggested a stand alone BEC would sort out my problem so I bought a stand alone BEC and powered it with a 6v receiver (which was initially charged up to 7.5) this worked for a very short time but then the receiver kept switching off and on. For someone who doesn't know about electrics (ME at that time) this was just a variation on the original problem.
 Now that I have 12v going in and the same stand alone BEC it means that there is enough power going in and the BEC provides 3000 to 5000mah which is enough for my servos


Wow, I actually get it, and I can now see why it wasn't working. It'll also help me with future builds.


Again thanks to all who have taken the time to help, I hope that by writing it out like this may help some others who don't understand 'the black arts'......... U2



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malcolmfrary

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Re: Why do I ever get 'normal' problems? Help please
« Reply #13 on: March 27, 2016, 09:44:04 am »

Strictly speaking, there should be a difference between U, u and µ in this context, but in all probability, it depends on what the guy writing it can find on his keyboard.  The chances so far are that if it does have one of them before the "BEC", it will be a switching type with low power loss rather than a linear type that dumps waste energy in the form of heat.  It will probably join words like "electronic" and "digital" as a fairly meaningless eye catcher for the unaware. 
If the winches contain electronics, as opposed to just being a motor and gearbox, they, too will have the same voltage limitations as the rest of the system.  What type of winches are being used an what kind of load are they getting?
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malcolmfrary

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Re: Why do I ever get 'normal' problems? Help please
« Reply #15 on: March 28, 2016, 05:10:08 pm »

The UBEC shown is definitely a switching type, both from the claimed power rating and the toroidal choke on the output lead intended to stop any interference generated by the regulator.
I would only use those winches on a 5 volt supply, or at least, a regulated one.  I have let the magic smoke out on 5 NiMH cells.  I suspect that if it had been constantly working, the "freshly charged" voltage would have reduced, but it didn't and the circuit, not doing any work, saw too much voltage.  I have looked at the insides of them, and, while the mechanical bits look and work great, it is very noticeable that the circuit board is a lot smaller than that in a "normal" servo of the same size.  Being old fashioned,  have to suspect that the electronics' current carrying ability is a bit marginal as a result.
Having said that, if they are powered by a regulated supply that supports the current that they want, everything should be fine.
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Re: Why do I ever get 'normal' problems? Help please
« Reply #16 on: April 03, 2016, 09:11:00 am »

 :(( :(( :(( <:( <:(


Everything was fine until I arrived at the water for my first test...... Then the problem started again >>:-(


I think it's allergic to water!


New radio on order! If that doesn't solve it new hammer on order <*< ............
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Re: Why do I ever get 'normal' problems? Help please
« Reply #17 on: April 03, 2016, 01:25:03 pm »

Well after a morning of trial and error i actually think I have found the problem  8)  (U2 puts on dark glasses and whispers just in case the problems listening)


I think (yes think) it was a faulty battery pack. The pack seemed to charge ok originally then I started getting this problem. After all what went on (see above) I found a different battery pack today and gave it a go. No matter what I did I could not get it to fail. I re tried the other pack and after a few goes it failed. Back to the new one and Nemos your uncle....... No fail


Could it be fixed? Or could it end in tears?.........


Now for me a 'normal problem' would be plug something in and there is a fail, unplug it and all is good, re plug fail again and then you know where the problem lies. But when you plug something in and sometimes it works and sometimes it doesn't makes things hard for someone like me


Let's see how I get on, first outing as soon as the weather allows. U2





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Re: Why do I ever get 'normal' problems? Help please
« Reply #18 on: April 03, 2016, 01:56:50 pm »

It would be good to know what radio set you are using.
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Re: Why do I ever get 'normal' problems? Help please
« Reply #19 on: April 03, 2016, 08:02:55 pm »

Hi Micro, it's a Futaba T 10 cap with an R60 14 FS receiver.
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Re: Why do I ever get 'normal' problems? Help please
« Reply #20 on: April 03, 2016, 08:54:10 pm »

Then no switching bec is needed as the receiver's digital circuitry is already regulated. You could safely use a 2s LifePO4, a 5 NiMH as a receiver pack or a 6v Pb battery for the R6014 FS receiver.  With four winches I suggest you change to a 2s Lifepo4 battery in conjunction with a 2sLiFe/LiPo bar graph meter.
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Re: Why do I ever get 'normal' problems? Help please
« Reply #21 on: April 04, 2016, 08:00:48 pm »

Micro I greatly appreciate your assistance with this matter, however since I found the battery pack to be faulty I removed the said pack and the UBEC and just tried it with a new 6v NiMH plugged into the receiver and it's great I even managed a confident maiden voyage this evening and all went smooth  :} , well almost, nothing electrical just my piloting skills and a small learning curve but other than that  :-)) :-)) :-))


Thanks for the info about my receiver I didn't know that. I will stick to the 6v NiMH as I have fitted a lead which allows it to be charged in situ.


As a mechanically minded person who knows very little about electrics it threw me when the original pack said It was fully charged but still gave problems. I never imagined it to be faulty. My mechanical way of thinking is sort of like......... A cog with teeth works......      A cog with teeth missing gives problems. A cog with teeth missing never sometimes works perfectly and sometimes doesn't! The original faulty pack seemed to work just long enough to get me next to the water before 'going funny' >:-o


Thanks for your help with this as it could have meant all my hard work for nothing. Appreciated  :-))    U2

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Re: Why do I ever get 'normal' problems? Help please
« Reply #22 on: April 04, 2016, 08:48:46 pm »

Depending on the nature of its dudness, a cell in a battery can either be totally disconnected (sweet nothing from the battery, easy to spot), shorted (battery is short of a volt or two, fairly easy to spot) or one cell has gone high resistance.  Without prior experience and the right tools, this is a pig to spot, and "smart" chargers are very little help.  The failed cell very quickly reaches the full voltage and the smart charger just sees a full value of volts and not much current going in.  So, according to its logic, its full.  So it stops, as it should do.  I prefer a dumb charger and a meter for most jobs.
Hydraulically (the usual analogy used to try to understand electric) it's the equivalent of a furred up pipe.  You can have lots of pressure but little flow.  Mechanically - maybe a cog with a wonky bearing causing it to deflect ant miss under load??
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Re: Why do I ever get 'normal' problems? Help please
« Reply #23 on: April 14, 2016, 07:53:24 am »

Don't worry the problem is not back {-) ....... There was a different problem however and again it wasn't 'normal'..... (It's now sorted) Here it is anyway.....


Due to sailing in too strong a wind for my skill level my boat ended up at some very steep angles and let a bit of water in.... Not a lot but enough to wet the motor.


After a thorough drying out I tried out the motor. It didn't work :((  I noticed that when I clicked on the switch the ESC fan turned and de selecting it turned it back off again. In my head that meant that out of the 4 items in my circuit 3 were working. The battery, the micro switch, the ESC but not the motor.


But knowing how electrickery likes to con me I decided to hook up my motor to the ESC on my other boat just to double check. It worked!....... %%  It was the blooming ESC that had blown, but tried to trick me by still turning the cooling fan. Gotcha.......... New ESC ordered!


The ESC was situated too low down in the boat and had apparently also got wet. I will refit the new one to the underside of the deck out of harms way.  U2


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