Electrical snag in old One Metre

[SimonCornes]

For the last couple of weekends I’ve sailed my old boat and in both occasions I’ve had a situation occur where I’ve lost sail control with sails about half out but still with rudder control. I was able to recover the boat and indeed the winch began to work normally again but when you’re sailing with full sized dinghies about who are racing you really don’t want to lose sail control!

I wondered if it was a duff battery as I used individual AA cells in a Maplin 6 pack with one dummy cell and a PP3 connector so i bought a new welded 5 cell AA pack. 
 

The winch is a Whirlwind Olympic I think - a 6 volt one because I was using a nominal 6v pack. My radio gear is Radiolink and my Tx normally shows Rx voltage as 5.1v as supplied via the winch. At one point I noticed the voltage at 5v but it went back up to 5.1v . 
 

Does anyone know what might be happening??  
 

Thank you for any answers/advice!

Simon

Edited August 25 by SimonCornes

[Lester Gilbert]

Hi Simon

Sounds like the winch drops into "safe" mode when it can't get enough power -- amps as well as volts.  The Whirlwind would be more than 20 years old, I guess, they were unreliable from the start.  It was their first digital winch, if I remember correctly, and Whirlwind sadly went out of business as a result shortly thereafter.

The lack of power is as likely to come from inadequate wiring as from an inadequate battery pack.  If you are using a Futaba connector and servo cable, it may be that it is good for signal connections but not for power.

There is also the question of why the winch may want more power than can be delivered -- sheeting line snag or hang-up, excessive friction especially around seized blocks, rusty winch gearbox bearings?

[SimonCornes]

That’s interesting Lester and, yes it’s more than 20 years old but having said that I used it from when I built the boat in around 1995 and then there was a hiatus of around 23 which ended last year and the winch has performed perfectly since then. I haven’t changed anything but I can see what you mean about the winch going into ‘safe mode’. It was pretty breezy today and I was using the working suit.

[John949]

There is some info on Whirlwind winches in this thread:

https://www.rcuniverse.com/forum/rc-sailboats-89/4348956-whirlwind-olympic-winch.html

 

No mention of a fail safe or other low voltage protection system but it does sound the most likely answer to your observed behaviour.  I've tried to repair a couple of whirlwinds for friends with a 50% success rate.  The failure was due a track fault in the potentiometer and a can't find a replacement - even if I could the pot body has flats machined on it!  Anyway it means I have some spare parts for a red whirlwind should you need them.

If it is a low voltage issue then you should be able to replicate it by deliberately stalling the winch.  A standard AA cell is going to struggle to produce enough current for a big winch, NiMh is better.  LiPo or LiFe would be better still, but the higher voltage might fry it if it stalls.  

P.S. A 20 year old winch isn't going to be digital, indeed I have yet to see a true digital sail winch.  The control loop in some of the latest ones might use a processor, rather than analogue electronics, but the feed back is still an analogue voltage and the inputs are PPM.  

 

[Lester Gilbert]

My bad, it was the "Tensor" which was their first digital winch which was problematic, the "Olympic" was their earlier, standard analogue, design, and had very good reliability apart from a tendency to overheat when pressed.  "Digital" refers to the control electronics.

Edited August 26 by Lester Gilbert

[SimonCornes]

In my experience my David Andrews winches have all performed very well in fact I used to sail with David and Elizabeth from time to time in the Midlands District and never had any reason to doubt David's product. I'm pretty sure the winch in my Metric Magik is an Olympic, not a Low Profile and your suggestion, John, of a worn pot track might be the thing - if you stop at that point then it might not start again, until it feels like it. As its in the roughly 'broad reach' position then that's a bit awkward and if replacement pots don't exist then I may be snookered but I will carry on trying and perhaps try to sail on less broad reaches to avoid that stick position on the transmitter!! A bit of playing around may be required!! Thank you very much for your various inputs, it's reassuring to have at least half an idea of what might be happening! Mind you I wonder what the voltage drop means? Its a brand new Rx pack that I have charged twice using a modern fairly fast charger so I may switch from 0.4 MaH to 0.1 MaH to see if that helps although I don't see why!

[Trevor]

Have you tried some contact cleaner/lubricant on the potentiometer? Needs to be proper stuff as other cleaners or solvents could make it worse. 

[SimonCornes]

5 hours ago, Trevor said:

Have you tried some contact cleaner/lubricant on the potentiometer? Needs to be proper stuff as other cleaners or solvents could make it worse. 

Hi Trevor. I have never taken my Whirlwind apart so I have no idea where the pot in question might be located? Can you advise??

 

[John949]

The Whirlwind uses a 10 turn pot (like the older RMGs) - so it's a large cylindrical device located in the space under the output shaft.  It's actually bigger than the motor and the body has three flats machined onto it to make it fit into the casing (and stop it turning).  Unfortunately it is fairly well sealed so contact cleaner isn't going to be easy.  The pot itself is glued together and I wouldn't advise trying to dismantle it unless you know what you're doing.  In the one I looked at, the glue had failed so the pot fell apart.  Getting the delicate internals back together is tricky.

I'd be happy to take a look at it if you want.  Pretty confident I could at least identify what the issue is and I may be able to fix it.

[SimonCornes]

Hi John

Thank you for that. I’m thinking that if I try to sheet out further or in tighter then I might avoid that point? I know that’s a bit optimistic but I’m not seriously racing this boat.

Something that occurred to me is that most Whirlwinds are designed for 6 volts and yet my NiMh packs all charge to more like 7 volts so maybe I’ve slowly fried the pot?  I really have no idea!
 

But I may take you up on your offer but leave it with me!

Thanks

Simon

Edited August 27 by SimonCornes

[John Bennett]

Hi, after thinking you are running at too low a voltage I have just gone and had a look at an old Whirlwind Olympic in my box of bits and it is clearly marked Max 7.2v.  This in the past has meant use a 6 cell nicad/nimh (yes I know a fully charged one can be 8.4v but that's how servos used to be rated).

So I think your winch is cutting out in order to preserve the 5.1v going to the receiver and hence steerage, and when not loaded for a while the voltage will recover slightly and allow the winch to work again for a while.

You could tell us exactly what battery pack you are using so we can check if it will allow a reasonable current draw too. 

 

[SimonCornes]

16 hours ago, John Bennett said:

Hi, after thinking you are running at too low a voltage I have just gone and had a look at an old Whirlwind Olympic in my box of bits and it is clearly marked Max 7.2v.  This in the past has meant use a 6 cell nicad/nimh (yes I know a fully charged one can be 8.4v but that's how servos used to be rated).

So I think your winch is cutting out in order to preserve the 5.1v going to the receiver and hence steerage, and when not loaded for a while the voltage will recover slightly and allow the winch to work again for a while.

You could tell us exactly what battery pack you are using so we can check if it will allow a reasonable current draw too. 

 

Thanks John,

Dave Andrews made most of his winches to operate on 6v but the Olympic was the only one to have an option for a 7.2v input as well as 6v.

I used to use 5 cell NiCd packs, typically 800 mAh so 3 packs for a days racing like a Nationals. I also used an Andrews battery charger with 4 outputs - 3 Rx and 1 Tx and that worked fine. I am now using a 5 cell 2,500 mAh pack, having had issues with an iffy connection somewhere in a pack based on a Maplins  6 cell battery holder, 5 x 2000 mAh NiMh cells and one dummy cell with a PP3 connector on the battery holder and a PP3 fly lead with a Futaba plug on the end. Because of the intermittent faults Id sometimes get - complete lack of power to the Rx - I decided to buy a 'proper' pack, the 2,500 mAh one. I imagine we all charge our NiMh cells with a smart charger and I have charged at 0.4 Ah and, as you say, the cells seem to finish charging at 7+ volts but probably drop back to 6.55 or so once the charger is disconnected. I am contemplating fitting a Futaba socket to one of the outputs on my old Andrews multi charger and using that to charge my NiMh pack and maybe the charged voltage will drop to 6v ?? David was adamant with his winch labelling that it was 6v max unit and as the winch is probably 40 years old, maybe it doesn't like 7v ??   

Edited August 28 by SimonCornes

[Lester Gilbert]

On 26/08/2024 at 12:20, SimonCornes said:

a worn pot track might be the thing - if you stop at that point then it might not start again

Hi Simon

Did the winch go to half out uncommanded from close hauled or running?  Or did it inexplicably stop at half out when commanded to sheet in from running or sheet out from close hauled?  If the first, I'd guess safe mode when overheated and/or excessive voltage drop.  If the second, I'd guess worn pot, rusty gears, and/or rusty bearings.

[SimonCornes]

To be honest Lester I don’t know! When I think about it I’d say I sheeted to a broad reach rather than an uncommanded sheet movement so that would be the second option. I doubt it’s rust because I think everything is either brass or alloy with maybe steel case screws? Probably a worn pot then but I wonder if this is due to using more than 6 volts??