I have a Bismarck. I was at the lake today and burned out my second resistor in a week. They are 25 watt, 3 ohm resistors. I have them on a 12 volt system. I am looking at a different option to a resistor but just wanted to see all the choices out there. Also, if somebody had the same problem, please help!!
What are you using the resistor for? What circuit is it in? You're only going to be able to draw a little over 2 amps through it on a 12V circuit, If you have it in series with a motor I wouldn't be suprised if they were seeing more than 2 Amps.
What is the purpose of the resistor? Why are then in the circuit to begin with? Speed control? If so Id suggest either using an ESC or just going with a basic H-Bridge switch design, using a resistor is going to waste a lot of energy. ESCs are more expensive and easier to destroy but allow adjustable speeds. H-Bridge's are fwd-off-rev but are cheaper and easy to fix in the field.
I would run try dropping the system down to 6 volts, the motors would slow down also. If it is close, tweak the props if that is a option. Also a metal band wrapping the motor will drop it's rpms.
We used to use heavy duty wire-wound rheostats to provide speed adjustment in club ships way back, with an H bridge switch for fwd/rev (aka MAG switch). We have since moved to much more efficient geared motors and an ESC - ends up costing similar or less than the previous setup, gives variable speed, better battery life, greater reliability, etc. Cheers,
Wow, people still use this old tech in their ships??? Oh wait I've had one in my LST since 05. Wonder when that thing will die? But she's got such tinny motors and props there is no heat build up at all. My first Swampy kit came with a resistor, I was not sure what to do with it. The first thing Curly (Local vet) did when he opened my ship was laugh and toss it in the trash.
Hey are you the Alex that put up the two videos recently? I just saw them yesterday for the first time. So you already have the Biz on the water? What is your primary group IRCWW or MWCI? Thanks, Johnny
I think that is what I am going to go with, the ESC. Yes, that is me in the youtube videos. I am IRCWW.
I would like to see the finished product. You got us all excited on youtube with the teaser and all. Good luck on the upgrade. BTW one of our ace captains is using the banebots 45amp version, encased in epoxy.
Would that be Phill? I didnt know anybody was excited about my videos. I guess I will have to get the next ones out right quick.
For ESCs, If you are new to them, I strongly recommend you read the article "ESC's Lessons Learned" on the NTXBG.org knowledgebase. And, specific suggestions - Purchase an ESC rated to the maximum rated stall current drqw of all motors atttached to it. A 550 style motor can draw over 85A each at stall. If you use a 15A ESC on a pair of 550s it WILL let the magic smoke out, probably at some inopportune moment. Know what to do with the red wire (see article), or you risk letting out the magic smoke. Be sure you know the features of the ESC you are buying (there are a plethora of featuresets). What you want is one with forward and reverse, no delay in going form one to another. Some have different limits in forward or feverse, or have a delay going from fwd to rev, or the other way, or both. Some (the Polk) have a limit on time spent in rev (not something great for IRCWCC, where combat in reverse is permitted). All of the above said, I have been using ESCs for a long time, and have had great success. I highly recommend you get to know about them. But, like anything else, there is a bit of a learning curve. Cheers,
One other thing... forgot to mention. If you overload the resistor due to resistance whether through a combo of resistance of the motor prop shaft against the stuffing box, weeds or bottoming out you can overolad the resitor and burn it out. Maybe a resistor for each motor would solve the problem. If your motors are undepowered and drawing more amps due to excessive load that could translate into the resistor and cook it. Just some things I Noiticed when I was using resistors in Bismarck in the early days.
I am old school too. I have used the old swampy resistors forever. I would prefer to use those but I don't mind checking out other options. That is my current theory right now. My prop shaft is causing too much drag on the motor increasing the amps needed and frying the resistor. I ordered a new resistor and grounded and greased the prop shaft so it spins nice and smooth. hopefully it will fix the problem. I have the same set up as you for the Bismarck. One big motor, straight shaft with a dog bone, no gears. I still need to battle my beast but I would really like to go to NATS.
I will install my new resistor and let you know how it goes. If your using the same motor and prop I found that if you can spin the prop and it rotates around at least twice then your good to go. If it barely spins than you may have to run it on the table to get the grease moving around inside the stuffing tube. I remember one time I had a type of plumbers grease and I packed it in tight in the stuffing tube. Well the prop barely turned over once by hand. In the water it created a lot of resistance making the motor work that much harder. I just use lithium grease now and it works fine. How is the alignment between the motor shaft and universal joint to prop shaft? Make sure no binding there. Make sure your motor's front opening is not complety covered up. It needs air on that side of it to keep from over heating. Also when bolting the motor to the faceplate of the motor mount if that's the way you have it make sure it's not over tight. That wil put stress on the motor. Do you have the pump wired through the resistor or is it seperate? For setup I just used the original wiring setup from Swampy's old kit and it works like a charm. I still have the orignial copy from the kit. There was 2 incidents I had with this motor. One I got th e briight ideal to spray WD-40 in side the motor can. Well that's because I never lubed the darn thing after 6 yrs of hard use. Doh! 2ND was a biszarre one. Those lare openings in the motor can on the sides are quite accomodating to small bbs that spill over when loading C turret Cannon. Put a screen over this area to prevent bbs from entering the can. See a bb stuck there can jam the motor and grind it to a halt or make the worst kind of noise short of throwing a rock in a dryer on high spin. Other than that that's about it on that part. Looking forward to teaming up as well with all the Bismarck's that wil be there.
From the sound of it you and I do have the same motor. But you can never really tell untill they are side by side on a table. I have never had a problem with my pumps. I did wire them backwards so I only got a 6" stream instead of a 6 ft stream but that is really the only problem I have had with my pumps. I have grinded down the prop shaft a little bit and it is making a huge difference. I think that is why my resistors are burning out. Im thinking Im going to replace my entire prop shaft and tube. The tube had a dent in it when I bought it. I didnt think it would be a problem but I guess it is along with a couple other things. Thanks for the advice. Do they have a date for NATS?
