This question is two fold: I am buying two ESC's for a boat. I am using these motors: http://www.allelectronics.com/make-a-store/item/DCM-229/3-12-VDC-MOTOR/-/1.html It says on the site there that each motor draws 1.2 amps at 6 volts. I am running each motor at six volts (four AA batteries) so I assume that this ESC should work: http://servocity.com/html/c-7_speed_control.html If there is any doubt I will get a size up, better to spend a little more than to see the "blue smoke" I keep hearing about... Ok, second question. I see on that ESC a connecter that goes to the radio receiver. Then, however, I see TWO other pairs of wires, both of which are pictured at the bottom of that page. My question is, which one do I use as the terminals of the "switch" when using the ESC and what does the other pair do? Or do I connect my battery pack to one and the other leads directly to the motor?
First, this ESC will NOT work for you. 1.2 amps is no load. Once you are in the water, you will probably be more like 10A. Once you get moss on your props you could be as high as 90A /ea. You need fuses and probably more like a 40A ESC. Two: The two blue & black wires go to battery. The black three-prong plug goes to servo control The red two prong plug powers the receiver (+5V)
Do you think this 50 amp ESC would be more suitable? Money is an issue, but I don't want to burn them out either. http://servocity.com/html/c-50_speed_control.html On which end would I attach the fuse? Between the battery and the ESC? And what fuse rating would you recommend? I assume I should go just under the ESC value at ~45 amps?
Not really. An aircraft ESC has two things against it; it's not waterproof and it doesn't have reverse. A better ESC would be one of the cheaper rc car ones with reverse. They are not waterproof, but you can make them water resistant. Best ESC though is boat ESCs. They are already waterproof and include reverse.
Do you have an ESC or a site in particular that you would recommend? I'm obviously pretty new at this so I am still finding out which stores are good.
A few things I should mention: 1. This boat isn't a battleship, it shouldn't sink or get water in it at any time. 2. Obviously those motors are brushed so the ESC needs to be brushless. 3. I have a $100 budget for these, so each one shouldn't be over $50 Does such an ESC exist that can handle the 40 amp current?
This one looks pretty attractive, its a little more than I wanted to spend, but I don't think that can be helped http://banebots.com/pc/ELECTRONICS/BB-1245
Something from Mtroniks's Viper Marine series or a Dimension Engineering Sabertooth. The Mtroniks are already waterproofed, Dimension Engineering's arent but its pretty easy to use some scotchkot and waterproof it yourself. I personally like the sabertooths better, but either should work for you. What boat is this going in, what type of props are you using, gears or dogbones, etc. That makes the biggest difference on what you should get.
It's actually a research boat model, eventually it will tow a small camera sled for looking at the bottom of lakes, etc. The motors are dog boned to the shafts and the props are, I think, 1 1/2 inch in diameter.
In fact, I should go to one of the local RC combat battles when this is done and take some footage of some of their sunken boats, that would be interesting.
Oh...that changes everything. They arent good combat ESCs but for you a PROBoat ESC might work, they are already waterproof, and pretty cheap. If your motors are pulling 40 amps you have other problems besides what ESC you are using. I'm betting that the current draw for your motors when they are in the water will be in the 2.5-5A range each. I run a similar setup and mine run at the low end of that range, maybe a little lower, but they are different motors and they are geared, but I think the prop is 1.75".
If the ship isn't a battling ship and isn't in any danger of sinking, then you could get away with a standard brushed (not brushless) esc with reverse. I did a quick check on Tower Hobbies/Horizon Hobbies and found: car esc @ Visit this site another car esc @ Visit this site a boat esc @ Visit this site another boat esc @ Visit this site If low cost is the primary factor, you could go with a servo operated switch. You will have to use gears to set the ship's speed. You'll probably have to use a gearbox anyway because the motor you have chosen runs a little fast for direct drive applications (assuming you are going to use a 6v battery).
I tried the servo operated switch, however the proportional control is really important for towing; I need to go fast on the way, then slow down when I get there Thank you so much for the links, I might get one of those boat ones. In my book $80>$120
I want to get this one, I think: http://www.horizonhobby.com/Products/Default.aspx?ProdID=PRB2314 The problem is, my radio is Hitec and this uses Tamiya connectors. Is there somewhere I can buy some sort of adapter? Also, it says that it has a motor limit of "15 turns." What does that mean? Is it referring to the coil inside the motor?
Motor limit refers to the number a windings a motor has ... a common way to label motors in the rc car and boat world. That particular speed control will handle 50 amps forward and 20 amps in reverse. Should be more than enough to handle the twin Johnson motors.
Thank you all so much! I think the free membership at this forum has saved me a few hundred bucks already...
One last question though, what IS the deal with those Tamyia connectors? I'm guessing they won't work with my Hitec receiver? How do I fix that?
Ok, I figured that out; I found the manual in PDF form and it does have a hitec-compatible connector. One last question. The manual insists that I should cap my motors. I've seen this done and the manual gives directions, however I have no idea what values of capacitors to use. Does anyone know?
I love hearing that. ...I have been known to accept donations... Money, beer, sex (well.. maybe not from you, no offense.), or boat parts. [8D]
