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Author Topic: New question ... power for four winches?  (Read 1531 times)

Unsinkable 2

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New question ... power for four winches?
« on: February 07, 2016, 07:58:34 pm »

 :embarrassed:  I took the winch servo from a boat were it was using too much power from the ESC and causing problems with the other servos. The winch was not faulty just greedy!


Anyway, my new boat will require 4 sail winches, one rudder winch and will have a brushless motor connected just in case as a backup.


So my questions are.......


Am I better off powering everything from a 12 gel battery or a lipo for the brushless and individual nicads for each of the sail winches?


If individual nicads are used can they be wired to charge simultaneously?


If using a 12v gel battery with plenty of oomph is it the ESC that shares the power to the sail winches?


I just want the power to turn 4 winches and a rudder and be able to run the  11.1 brushless motor in emergency, this probably will not happen all at the same time as they will be controlled individually by dials on my radio, but I don't want to turn a dial only to find the servo won't respond.


I'm sure this has been covered before but a search threw up thousands of threads....... Thanks in advance. U2


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Umi_Ryuzuki

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Re: Last problem solved..... New question
« Reply #1 on: February 07, 2016, 11:00:37 pm »

You are better off powering the receiver directly from a 6v gell cell or
high amperage 4.8v NiMh or similar rated battery.


 :-)

dreadnought72

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Re: Last problem solved..... New question
« Reply #2 on: February 08, 2016, 12:09:00 am »

:embarrassed:  I took the winch servo from a boat were it was using too much power from the ESC and causing problems with the other servos. The winch was not faulty just greedy!


Welcome to my world! I have been there and worn out the teeshirt.


My ultimate electrical solution for Racundra was to use a big 12v 7A/hr lead acid battery. This powers two ESCs - one for the 12v motor, one for a home-brewed 12v jib winch. It also runs into a voltage step-down gizmo giving me loads of amps for the six-volt stuff. The receiver (and therefore main Hitec winch and rudder servo) run off the gizmo. I have one battery to charge, and can switch the motor out of circuit for virtually endless sailing-only time.





Andy
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malcolmfrary

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Re: Last problem solved..... New question
« Reply #3 on: February 08, 2016, 10:40:14 am »

Anyway, my new boat will require 4 sail winches, one rudder winch and will have a brushless motor connected just in case as a backup.


So my questions are.......


Am I better off powering everything from a 12 gel battery or a lipo for the brushless and individual nicads for each of the sail winches?


If individual nicads are used can they be wired to charge simultaneously?


If using a 12v gel battery with plenty of oomph is it the ESC that shares the power to the sail winches?


I just want the power to turn 4 winches and a rudder and be able to run the  11.1 brushless motor in emergency, this probably will not happen all at the same time as they will be controlled individually by dials on my radio, but I don't want to turn a dial only to find the servo won't respond.


I'm sure this has been covered before but a search threw up thousands of threads....... Thanks in advance. U2
As long as the emergency does not involve low voltage on the LiPo, your backup should be fine.
Does the ESC share power?  It has a voltage regulator circuit (BEC) that gives a regulated 5 volts on the red wire to power whatever is connected that way.  Mostly it is powering electronics, but in the case of servos that do not have a separate power supply, it it providing power for the servo motors as well.  If it can supply enough current to work them all, great.  If not it is time to consider other options.
If the separate voltages are supplied by different batteries, then if you use the right kind of circuit you can charge them simultaneously from a common point.  If you feel the need to ask, you would be better off charging separately.  Gel cells need to charge at a set voltage with controlled current, NiCad/NiMH need a constant controlled current, LiPo need a shop-bought specific charger.
Brushless motors do not specifically need LiPo batteries.  They are just bits of kit that don't care where the power comes from, as long as enough is available.  So far, the main brushless users have been those looking for high performance and low weight, so the combination of brushless and LiPo makes sense for them.  From this has grown the incorrect idea that ANY brushess motor MUST be supplied by a LiPO. A smaller, less demanding motor will be quite happy with any other type of battery.
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Re: New question ... power for four winches?
« Reply #4 on: February 08, 2016, 01:21:21 pm »

Thanks for the info guys and gal.........


Malcolm 'does the ESC share power?' That was my question but as you pointed out it has a BEC which gives 5v on the red wire that I think I may have my answer now....... Read on (maybe have a good laugh but if you do please let me know where I am going wrong)


DN72...... I want one of those tee shirts so here goes


I need a minimum 11.1v for my brushless motor (up to 18v)
I need a good 6v to power my winch servos (minimum 4.8 but at a lesser torque, I want 6v)
I prefer to have 2 smaller 6v batteries joined in series than one big 12v (easier to position in the hull and lower down!)
I want to charge the batteries at the same time with one connection.


 SO, will this work?........


I get 2x 6v gel cell batteries and join them together to give 12 v
I cut the red wire on my ESC and connect it to the 12v supply and plug it into my throttle channel on my receiver
I get a 12v to 6v reducer and plug it into a spare channel on my receiver


I think (hope :embarrassed: ) that gives me a constant 6v for my servos and should I need to use my motor it will run at 12 volts







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malcolmfrary

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Re: New question ... power for four winches?
« Reply #5 on: February 08, 2016, 08:15:03 pm »

Quote
I cut the red wire on my ESC and connect it to the 12v supply and plug it into my throttle channel on my receiver
I'm hoping I read that correctly.
The big thick red wire on the ESC goes to main battery positive.  The ESCs internal BEC provides a stable +5 volts for its own internal control and out via the thin red conductor for the rest of the system.  The "rest of system", with the thin red wire disconnected (don't cut it, just winkle it out of its housing and tape it back for possible later re-use), can be powered via either a separate battery or a more powerful uBEC connected to the main battery.  It is also, with a few more leads, possible to power each winch separately.  Be aware that while a lot of model control electronics was designed and developed with the use of nominal 6 volt SLA supplies, a lot of modern electronics, especially devices containing PIC chips, might well have an absolute max voltage of 5 and a very small bit.
Connecting 2 same capacity 6 volt batteries will give a 12 volt battery, but as you say, in a more convenient package.
Appropriate wiring diagrams live at - http://www.modelboatmayhem.co.uk/forum/index.php/topic,6169.0.html - and were put there to give beginners a good start.
How much sail area are these winches going to control?  I have used some 9Kg pull arm types and later some of the new drum types, both standard servo size quite happily in fairly serious conditions in a Victoria, which is a 5 lb boat carrying about 200sq in of sail.  No problems on 4.8 volts.
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Re: New question ... power for four winches?
« Reply #6 on: February 09, 2016, 07:55:33 pm »

Hi Malcolm, thanks for the reply. Reading it back my wording could (and was) easily be misinterpreted as the big red wire being cut. I was in fact talking about the small red wire that accompanies the black and white wires that plug into the receiver.


From your reply I now understand the ESC provides +5v to power itself and does not in fact reduce the main battery input down to 5v for the receiver.


Here is (hopefully) what I want to achieve and why......


4 sail winches which apparently use up to 0.35a at working current. A rudder servo (not sure how much it uses but it is a standard size servo with a bit of extra torque) and I have a small brushless motor that I would like to use should the wind stop or my sailing skills fail ( hi possibility as I have limited experience) I do not know how much power this motor uses. It says 11.1 to 14.8v


Now why....


Once I had built Lena I started having trouble with my rudder servo and my sail winch kept turning slowly even when the input to the sail winch was stopped. Ie the rudder stick was pushed full left and the servo slowly went left and at the same time the sail winch started to turn slowly. Sometimes I got a red light on my reciever indicating no signal. Power off and back on sorted the signal loss. Unplugging the sail winch sorted out all the problems.


My diagnosis was therefore a problem with the sail winch. I tried it by itself in the same reciever with all other things unplugged and it's fine.


At that point I asked about servo testers on here and opened a can of worms.....


Having being convinced that my servo was taking too much power (and therefore 4 would be way way too much) I have been trying to come up with a way of powering them, (6v)  and also having enough voltage to power my brushless motor if and when need be.


I now understand that my sail winches are not as power greedy as I was first informed.


So having been told that they use too much, then that they don't........ Use a 12v gel cell, then avoid a gel cell, use a 12v to 6v reducer, use a BEC, use the BEC in your ESC....... The BEC in your ESC if powered by a SLA might change the UBEC or the KV ...... OK I made the last bit up but none of it makes any sense to me so........


What I am going to do......


I am going to setup a system on my workbench with the four servos and attach a weight to each of them. I will then connect up my lipo and brushless motor and give it a go. They are supposed to be able to pull up to 10kg at 6v but I'll be happy just to see them all work before I fit them in my boat.


I would have preferred a battery that I could charge without removing it but I'll settle for a system that works and put up with removing and re fitting the battery.


You asked what boat it's for........ It's for my Alantis, which is virtually the same as an Atlantis


I'll get there in the end........ U2









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malcolmfrary

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Re: New question ... power for four winches?
« Reply #7 on: February 10, 2016, 09:15:36 am »

Quote
Once I had built Lena I started having trouble with my rudder servo and my sail winch kept turning slowly even when the input to the sail winch was stopped. Ie the rudder stick was pushed full left and the servo slowly went left and at the same time the sail winch started to turn slowly.
Most ready built sail winches act like a normal servo - they take the pulse coded signal from the receiver, turn it into a voltage, compare that with the voltage from the position sensing pot and if there is a difference, drive the motor until they agree.  Staying put does need the voltage to the servo to be stable, any change will cause the servo to drive to a new position. 
Unfortunately, there are faults internal to the servo that can give very similar results.  My home made winches, when I just used the original servo innards, did suffer from the very narrow deadband that servos have.  Using a "proper" ESC to control the winch motor cured that.
Add to the servo telling itself that it needs to move, there is also the possibility that something might be happening in the other parts of the information chain between thumb and receiver output - the pot on the transmitter, the transmitter encoding that into the information stream for transmission, the transmitted signal, the receiver sorting it all out to the right channels.  Of course, the voltage to the transmitter pot needs to be stable as well, to ensure that the right signal is generated. In a digital world, it tends to be forgotten that there is a lot of analogue stuff in use, even in boxes marked "digital".
Eliminating the transmission chain is where the tester comes in handy.
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