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batteries for tug

Old 12-13-2004, 06:59 AM
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Brans
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Default batteries for tug

i wonder if anyone can help or suggest what power option i can use in my tug.
im using a speed 600 moto and a manual speed controller that i got with the tug.

the tug weights about 4 kg's and is aproximately 1.2m long ,
any suggestions on batteries what voltages and amps to aim for.

thanking you
brandon[X(]
Old 12-13-2004, 08:08 AM
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LtDoc
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Default RE: batteries for tug

Brandon,
With a tug of that size you have lots of options! Consider the battery(s) as also being ballast (rather than whatever is being used for ballast). It just depends on the voltage required for your motors. The sealed gellcell type battery would be my first choice. Not a typical lead/acid automotive type, but the truely sealed type. The fumes from lead/acid batteries can 'eat up' a model very quickly. Then it's just a matter of fitting the battery(s) inside the hull. If the voltage is correct and if it'll fit in the hull, then it ought to work just fine.
You never have enough current capacity, so, the higher the Ah ratings the better!
With a boat of the size you have the 'problem' isn't so much powering the thing as it is transporting the thing - LOL!
One suggestion if you happen to have a few $$$ laying around, is to convert from the 'mechanical' speed controler to an electrical one (ESC). It just makes for a more realistic acting boat. Mechanical speed controlers tend to produce lots of heat, and depending on how they are built, they can turn your boat into kindling and produce very realistic smoke (basically a resitor network, right?)...
Have fun...
- 'Doc (W5LZ) / 73
Old 12-14-2004, 10:18 AM
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Ron Olson
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Default RE: batteries for tug

If we knew the brand and name of the tug it would help a lot. I've seen the big tugs like the Dumas Miss Darby use deep-cycle marine batteries to help get it down to the waterline.
Old 12-15-2004, 08:12 AM
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Brans
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Default RE: batteries for tug

Thank you for the advise, im not to sure what the name of the tug is.
i can send you a email with the pics of the 2 tugs that i have.

I phoned our general hobby store looking for a speed controller to replace the 3 step machanical one i have.
The wanted to sell me a speed controller rating of 30amps. When he heard i wanted to use it in a tug he immediately said that im going to burn it out in 5 minutes is he wrong or do i have look at some other option.

My idea is to run either 2 6v gel battery packs in parrallel ( those house alarm batteries ). I dont want to exceed more that 25 amps.
I was thinking of running 2 7.2v , 5 amp packs is my other option.
Can i get away with running a 12v moto cycle battery in there with a regulator.
If you have any idea what power source i can use in the tug. I want to be able too run it for about 4 hours will be satisfying.

I have Managed to build a cooling coil for the moto as i see it gets quite hot after a few minutes of running.

Thanks to all with suggestions.
Old 12-15-2004, 08:30 AM
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Brans
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Default RE: batteries for tug

here are the pics of the two tugs that i got.
any suggestions on a power pack for them. One is a single moto and the other is a twin moto configuration.


thanking you
Brandon
Old 12-15-2004, 08:34 AM
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Brans
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Default RE: batteries for tug

Here are the pics of them.

Thanks
Brandon
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Old 12-15-2004, 09:21 AM
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Default RE: batteries for tug

Brandon,
The current requirements of your motor(s) determines the rating for the ESC. You find out the total current required by a motor by doing a 'stall' test on it. (Hook the motor up, supply current with the shaft clamped so that it can't turn. That's the maximum current required for that particular motor.) The ESC's current rating has to be at LEAST that much, and of course the ESC has to be rated for the voltage of the supply. Is 30 amps enough? Beats me, don't know what the motor's requirements are.
I can certainly be wrong, but I think 4 hours is sort of unreasonable. Depends a lot on 'how' you run the boat, just putting around, high speed runs, pulling skiers, etc. Duration isn't too hard to figure. Divide the total current rating of the battery(s) by the number of amps being used. For instance, a 4 Ahr battery running a motor drawing 1 amp should last for about four hours. The same battery with a motor drawing 20 amps will only last for about 15 - 20 minutes. A 10 amp draw for four hours means a battery of at ~least~ 40 Ahr rating (getting to be sort of a big battery!). Because 'real world' circuits are never quite as efficient as those on paper, the duration is always a bit less than what the 'numbers' tell you it will be. Not ~that~ much of a problem, but you should be aware of it...
- 'Doc

PS - You never have enough current capacity. The 'other' side of that coin is that you never have enough 'room' to squeeze enough capacity into a boat, unfortunately...
Old 12-15-2004, 01:27 PM
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Default RE: batteries for tug

Brandon,

Looks like a 12V flight box battery will work in those boats. I use them for my boats. They are cheap (under $20.00 each) and depending on your setup, give long run time. Also, you were asking about ESC's. I won't tell you what to buy but I will tell you I have been using Proboats ESC's for a couple of years now. They are cheap ($40.00) waterproof and very easy to set up.I purchase them from Horizon Hobbies via the internet. On that sized boats I would also consider using geared down 550 sized motors. You don't want those boats to plane, they are displacement hulls. In addition to having much more "tugging" power, the geared down motors will allow longer run time due to using less current (Amps) Like the other posts mentioned though, you have to find the stall current on the motors you are using. I believe the current rating on the Proboats ESCs will work for you but check them first. The boats look like they could be Model Slipways (the one in the foreground anyway, but I am not sure of the other one.

Hope this helps,
Pete
Old 12-15-2004, 04:31 PM
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pompebled
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Default RE: batteries for tug

Hi Brandon,

I my opinion a geared down 600 is not the best way to go, apart from the noisy gears, the efficiency is not great.
As you want long runtimes, I suggest you look for a 12-18V motor, in the 800 or 900 size and run it on 6-9 or 12V, atleast half the motors advized voltage to assure low Amp draw and long runtime.

These motors turn big props in direct drive without any problems.

Sources for suitable motors are:
- Copiers; I run a couple of surplus 16V motors on 12 V, average draw 3-5Ah, in a tug your size with a 20Ah gel batterie that's a long runtime.
- scrapyard; the electric motors that drive the motorcooling fan are very suitable, very cheap, build to last, often with ballbearings and in your tug, low ampdraw and tremendous torque.

As others already mentionened, don't go for a small ESC, when you catch something in the prop, ampdraw can/will rise dramatically and smoke your ESC 40-60 seems the minimun to me (per motor).


Regards, Jan.
Old 12-17-2004, 07:06 AM
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Brans
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Default RE: batteries for tug

I got hold of a 12v 20ah battery pack that comes out of a UPS. The only problem that I found is that there is way too much torque and rpm, it feels like a speed boat not a tug and that was running of a mechanical 3 step SC. The problem I found was the first stage on that speed controller was way to fast.
I was just wondering if an ESC would give me an idling effect and not like the situation I have at hand. Slow and realistic with the configuration im running. ( Direct Drive )
I was doing some research on E.S.C in our local area. I found one that most of our guys are running a 50amp marine ESC water proof as well. I was reading on a website that explained that running the tug slower will cause more heat on the ESC. Would I have to gear it down to suite a realistic speed at full throttle or can I leave the way it is and just setup my radios (dual rates ) to compensate the full throttle scenario.

I took your advice and tested the current draw of the motor running freely and locked.
Running freely was average of 4amps
Locked was about 8amps
I’m going to run a 2:1 gearbox in there to see if it will help with the rpm problem.
A large Tug boat is a different scenario all together as I can see.

I have another problem do I have to run 2 ESC for the twin prop Tug and would a 12v 20amp pack be alright to run x2 400 motors.

Sorry for the long post. I’m dying to get it running and joining the other people with there tugs. Flying planes is my specialty but would like to broaden my pleasure.
Thank you very much for all the info that Rc Universe has given me. Hopefully one day I can help and suggest to others that have a similar problem. I guess that it is all about experimenting and burning things out isn’t it. Ha Ha.

Thanking you
Brandon
Happy Sailing
Old 12-17-2004, 12:20 PM
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pompebled
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Default RE: batteries for tug

ORIGINAL: Brans

I got hold of a 12v 20ah battery pack that comes out of a UPS. The only problem that I found is that there is way too much torque and rpm, it feels like a speed boat not a tug and that was running of a mechanical 3 step SC. The problem I found was the first stage on that speed controller was way to fast.
I have another problem do I have to run 2 ESC for the twin prop Tug and would a 12v 20amp pack be alright to run x2 400 motors.
Hi Brandon,

What's a UPS? (I'm Dutch...)

If you ran the 600 motor you mentioned in your first post on 12V, I understand why it looks way too fast; most Speed 600 motors are designed to run on 6-8,4 V ....

If you are content with operating both 400 motors simultaniously, one ESC will do.
Again, 12V is about twice the voltage 400 motors are designed for, maybe you can wire the motors in series, to keep them from going up in smoke under load?
BUT, if you catch something in one prop, that stalls the motor, you'll probably end up smoking them both.

There are 600 and 400 motors designed for higher voltages, use one of those, and go without gearing, or burning things up.

Regards, Jan.
Old 12-17-2004, 12:21 PM
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LtDoc
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Default RE: batteries for tug

Brandon,
Another option is to use a 'finer' pitched prop (or a smaller diameter prop). That would allow a higher RPM for any particular speed. Just a bit easier than gearing the motor(s) down.

If both your motors draw 8 amps stalled, then the controler should have a rating of 20 amps or more (8 + 8 = 16 + a fudge factor) if you use one controler. Or, at least a 10 amp rating per controler if you use one for each motor ( 8 amps + a fudge factor). If you do use two controlers you will have the ability to have differential motor control, use the motors for turning. Nice to have but not really all that necessary, in general.

A very 'rough' way of saying it is that voltage equals speed and current equals duration. Lowering the voltage to the motors will reduce their RPM, but also means that more current is flowing in the circuit so duration is lowered a bit, and you'll need heavier wiring to handle the higher current and dissipate the heat.

The following is a 'war story', so take it for what it's worth. I use a tug for retrieval so want all the 'extra' power I can get. That means that if I use the 'speed' stick on the transmitter the silly thing will almost get up and plane! So, I use the speed trim control for 'realistic' (sort of) model speeds. If when I tow/push something, I use the stick. It's all a matter of self control (which I admit I ain't got much of when I start chasing the ducks - lol). I'm not saying that's how you ~should~ do it, but it is an option...

Good luck and have fun.
- 'Doc
Old 12-17-2004, 12:25 PM
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Default RE: batteries for tug

Jan,
An 'UPS' is an Uninteruptable Power Supply for computers, in case the power goes off for some reason. the same sort of batteries are used for emergency lighting in buildings (you've seen the huge 'lantern' type lights usually mounted on a building's wall? Same sort of thingy...
- 'Doc
Old 12-18-2004, 05:38 AM
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Brans
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Default RE: batteries for tug

hi there, a UPS is a backup system for computers or any electrical device. ( uninteruptable power supply )Very handy when there are power failures.

Hope that helps.

I will reply on Monday.
Thanks for the info.
Old 12-18-2004, 07:11 AM
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Default RE: batteries for tug

Doc & Brans:

Thanks for the explanation, I thought as much, but, as UPS over here delivers parcels (without V & Ah), I wasn't sure...

Regards, Jan.

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