6 Volt or 12 Volt Motor?

[DGoodrow]

After much consideration I have decided to purchase the Dumas Jersey City tugboat as my first RC boat project. The electric motor for the JC is offered in both a 6 volt or 12 volt version.

What are the merits of one over the other and are there applications for both? Which one should I buy?

[CG Bob]

A higher voltage motor will draw less Amps; in theory the lower Amp draw means a longer run time per charge. The 12V system has some advantages over 6V besides theoretical run time. Do you want a working fire monitor? Install a windshield washer pump, which runs on 12 Volts. Thinking of installing one of the Ram (http://www.ramrcandramtrack.com/) sound systems? Most sound better on 12 Volts - more sound from the speaker. Are you planning on installing working navigation lights or spotlights? The model railroad section of the hobbyt shop has lots of lights that use 12 - 14 Volts.

[ThrustTugKeith]

I was at a hobby show (when I was into model trains) and saw a demonstration of L E D s that changed color when the voltage was altered.
I always thought this would be cool for nav lights. Simply change the voltage for red, green, etc. I think all L E D s do this. Now I gotta FIND them!!!!

Scott

[LtDoc]

Scott,
If you find those changing color LEDs, let me know where! Changing color with changing voltage is not a 'normal' property of LEDs, unfortunately...
- 'Doc

[RGinCanada]

A note on the LED's:

Red LEDs glow orange if you run them over voltage, and green ones glow yellowish. The change in color is usually accompanied by a great deal of heat, then a burning smell, and then darkness :D.

There are LEDs that consist of two LEDs in one package reversly connected across the leads. If you switch polarity, the color changes, and if you run AC current, the effect is a third color. RED/GREEN/YELLOW is the most common.

Hope this helps.

PS: its cheaper and easier to just buy red and green LEDs.

[DGoodrow]

for a guy just starting out it is safe to say that a 12 volt system is the system of choice for RC boats?

Also, any comments on the Dumas JC as a first project?

[Umi_Ryuzuki]

for a guy just starting out it is safe to say that a 12 volt system is the system of choice for RC boats?

Also, any comments on the Dumas JC as a first project?


Yes 12 volts is common. I was the odd person in our club by running my destroyer on 6volts. I stuck to it for twelve years before succumbing to the fact that lights, bilge pumps, and water sensing circuitry all ran better on 12volts. I think that old VW bugs were the same way. :p

The Jersy City seems like it would be a great first boat. If you haven't run across it already, take a look at the build up Pat Tritle did in the scale section. http://www.rcgroups.com/forums/showthread.php?t=233156

And, Welcome to the boards :cool:

[DGoodrow]

Since deciding that RC boats and model boat building in general interested me, I have been "lurking" this site...and others in an effort to educate myself. It was Pat's work that convinced me that not only was the JC a good starting spot, but that this forum was the most serious that I was able to find.

Regarding 12 volt systems, I have seen that batteries can be configured as 6 volt batteries in parallel or a single 12 volt. What determines that?

[Umi_Ryuzuki]

...

Regarding 12 volt systems, I have seen that batteries can be configured as 6 volt batteries in parallel or a single 12 volt. What determines that?

I think at best, we can boast that we are serious about having fun here. ;)

How one connects the battery terminals can determine voltage and amperage outputs.
If you have two 6volt 4amp batteries;

Parallel connects the positive terminals together, and the negative terminals together. The output would then be 6volts with 8amp/hrs.
When you attach a motor or lamp to one of the batteries, it will draw power from both batteries.

Series connects the negative terminal of the first battery to the positive termal of the second battery. The motor, or lamp would then be connected to the "positve terminal of the first battery" and the "negative terminal of the second battery". It will draw power from both batteries, but the output from the batteries will be 12volts at 4amp/hr.

[martin richards]

Boats are propelled by watts; not just vollts or amps but the product of the two. So 12 volt 5 amp and 6 v 10 amp both produce the same power (60 watts). However heat produced is more a factor of amps and the 12 v 5 amp set up will run cooler.

[CG Bob]

Boats are propelled by watts; not just vollts or amps but the product of the two. And the model Watts are directly related to the prototype SHP, and the scale of the model.

Scale of Model: 1:48
Scale Factor (the Cube Rule): 110,592 = 48X48X48
Prototype (full size) SHP: 5000
Prototype Watts (SHP X 746): 3,730,000
Model Watts (Proto Watts/Scale Factor): 33.7
Model Watts + 15% Scaling Factor: 38.8
Model Current @ 6VDC: 6.5 A
Model Current @12 VDC: 3.2 A

The 15% Scaling Factor for the Model Watts accounts for losses in scaling; we can scale the models, but we can't scale the water.

The example I provided is for a USCG 210' WMEC; the full size ship has twin screws. If I use a single motor and gear box to drive the screws, the motor would draw 3.2A @ 12VDC. If I install a motor for each screw, each motor would draw 1.6A @ 12 VDC.

[DanL]

I've found that if you are going to have one or two boats, use whatever voltage works given the motors, batteries, chargers, etc that you already have around. If you plan to ahve a lot of boats and need to buy everything up front, pick a voltage and standardize all your components (connectors, wire colors, charger, battery size and type etc) for flexibility, interchangeability and convenience.
I had 6 and 12V NiMH 4/3A battery packs (4.5Ah) before I started into RC boats. The 12V (10 cell) pack was too heavy for my first boat, so I went to a 6V (5 cell) pack. It's a 36" model of a slow prototype so high speed/power and battery life weren't issues. When choosing batteries, remember that even with 12 volt batts you will also have a great 5 to 6V power supply from your ESC.
I also had a lot of AA Nicads, so hooked them up in 7 cell packs for 8.4 volts output to power my second boat, a tug. 6 volts was sluggish, 12V was too much, so I went with 8.4V. Good speed range and no significant motor heating.
Also, there are some terrific new LEDs out called YeloGlo. They are a bright white LED in 3 and 5mm size and have a slight yellow tinge (rather than the typical LED bluish cast) and they look very much like an incandescent light. The advantage of the LED's is that they last almost forever, draw low current and can be used with any supply voltage by simply using a small current limiting resistor to get the desired brightness. The Yelo Glo's are available from Walthers.com model RR supply. 10 packs are only $11 or 12 now on sale.