jasonw

Rather than try to explain it go to the folowing page. Its on my forum maybe somone here can help? boat motor cooling?

FHHuber

What kind of power are you running to that motor? Sounds like you may be running WAY too much current... (too many cells or the motor is bound up... not getting up the rpm its supposed to.)

The cooling should be provided with a 1/8 id aluminum tube coil wound around the motor. (wind it a bit tight.. so you have to spring the coils out to shove the motor in.) There will be a water pickup line that has a metal tube beveled to face a bit into the direction the boat travels, and the water return lne should have its end beveled to face to the rear.

Too large of a prop... too many cells in the battery... binding in the drive line. Those are the places I'd be looking first.

At this point... you've probably already ruined that motor.

jasonw

I dont think I have ruined the motor yet. This is why I am seeking help so I dont mess it up. If I toss it in one of my cars it gets hot but dont all motors? Still runs strong and has butloads of power but just in the boat it fills the hull with smoke. I was runing 14.4V to the motor "2 7.2V packs" Now I only run one pack to it but it still gets just as hot and smokes just as much. I know this motor is an old one as the plane it came out of was old and out of production. I used the motor in my HPI RS4 MT for a while but Normaly I only do some rock crawling with that truck and it proved to not have good enough tourq for that. Trying to get more out of it I messed with the motors timing. Could it just be a timing problem? I dont know how to set the timing on these motors properly any other advice? As far as the aluminum tubing. The way the motor is mounted in the boat I can not wrap the tubing all the way around. Do they still make water jackets for electric motors? I can run the aluminum tube up each side "as I already do" and then down the bottom. Water Valume is also no problem. When runing at full speed it shoots the water 3-5 feet out the back of the boat were the exit tube is. Well hope to here back soon I hate leaving this boat on the shelf.

FHHuber

The problem is.. you've alread started to "let the smoke out" of the motor. The smoke is from burning the insulation on the winding coils. Once the insulation is burned... the windings start shorting out, reducing resistance in the motor... allowing higher current to go through until... you melt something and the circuit opens... (when all the smoke's out... it don't run no more.)

You'll hear people say its OK to put 2 battery pack in series on a motor... they're often wrong. A motor has a fixed internal resistance. (until you start letting smoke out...) voltage (E) is related directly to Current (I) times Resistance (R) (E=IR) IF E - 7.2 and I = 30 amp... R = 30/7.2 = 4.167 ohms. Increase the voltage supplied to 14.4... R is constant (can't change it) and current goes to... 60 amps! (this all assumes an un-loaded motor...) Add a load and the motor draws more current because there's an effect of the motor rotation increasing the internal resistance... otherwise, and un-loaded motor would have an essentially infinite unloaded RPM on 1 volt power. As the motor speed increases... just the drag of the brushes and the bearings can become a significant load... and excess voltage WILL burn up an unloaded motor.

You have to get into some college leve IEEE theory and calculus to prove all this... but the end result is, you've applied double the voltage the motor was designed for. You've toasted it. Its amazing that you didn't toast the ESC too.

jasonw

Well as far as the ESC gose I was not using one with the 2 packs I used a servo and micro swtch set up. So what you are saying is the whole problem is the 14.4V right? So If I stick with a single pack and spend a small fortune on a new motor I should not have this problem? Thanks for all the help be the way

FHHuber

The excess voltage was almost guaranteed to be a major contributor to the problem.

You still need to verify that there is no excess binding in ghe drive line. a tiny warp in the shaft can cause a lot of binding n the tube. A minor misalignment of the motor to the drive saft can also cause binding. Any binding will cause the motor to overheat. An ovesize prop for the motor would also cause excess load... and overheat the motor.

Inadequate cooling would almost never cause the insulation melting on the leads between the motor and battery. You've got to be putting too many amps through th motor for that. You might check what the max amp ratiing for the motor is and put a fuse in the + lead. Then if the prop is oversize and/or there's drag in the drive line... the fuse blows rather than trashing the motor.

jasonw

Well I took my new truck motor and put it in the boat and still the hull is full of smoke when the battery is done. I checked and the motor workes verry good and stays cool in the truck and just by feeling the boat drive train "by turning the prop with my hand" has less binding than the truck "by holding one wheel and turning the other with a hand" this is verry strange. I wish I coiuld figure it out as is is hurting my R/C boating fun. I almost never go out anymore. My activities now consist of 99.5% cars and.5% boatswhile it use to be the other way around

Pagemaster

Prop is too big and the boat is too heavy. In car terms imagine running the same size pinion gear and spur gear. What would happen? Not enough torque. Same thing on boats only most boats dont have gears, the prop acts as the gear system. Try a much smaller prop.

Steven Vaccaro
www.OffshoreElectrics.com