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Author Topic: Fuses Keep Blowing  (Read 2929 times)

RMB

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Fuses Keep Blowing
« on: June 25, 2014, 04:04:43 pm »

I have recently completed a Fairey Swordsman following Bluebirds very helpful Plan for Beginners article.  I have fitted a Hunter Systems RS540-SF motor controlled by a Mtroniks Viper Marine 20 ESC protected by a 15 amp fuse running a bog standard 35 mm 2 bladed prop.  The Swordsman sails beautifully with a good turn of speed, however, after five or ten minutes running the fuse blows.  Is it normal for this type of set up draw in excess of 15amps or have I got something wrong?

Martin Bright
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John W E

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Re: Fuses Keep Blowing
« Reply #1 on: June 25, 2014, 04:41:37 pm »

Hi ya Martin
 
Welcome to the forum my mate - when the fuse blows - is the motor and everything else red hot?
 
Just wondering if you have a coupling set up a little too close to the prop tube with very little fore and aft movement and a generation of heat is causing it to sieze up.    I have looked for the specs of this motor and typical of google you can get every other RS Motor specs apart from the one you have.
 
By the looks of it, its running current is about 13 amp which the fuse should handle quite easily - and so should the speed controller.
aye
john
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HUNTER

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Re: Fuses Keep Blowing
« Reply #2 on: June 26, 2014, 09:16:13 am »

Hi Martin,
It is very unusual for the motor to get hot under normal conditions as it has a built-in cooling fan. Likewise the ESC which has heat displacement case.
I would suggest that you look elsewhere for the problem, it could be in the prop shaft perhaps being tight in the tube/bearing caused by a small amount of bend in the tube when fitted. It could perhaps be the size and type of the propeller ie is it a fast electric propeller? Is the fuse fitted between the ESC and the motor or is it between the battery and the ESC.
 
For the motor to get hot a resistance between the motor shaft through the shaft to the propeller tends to be always the main reason. If the motor is dragging then the ESC will get hot and eventually blow the fuse as the resistance is increasing the current pull on the motor and the ESC and the fuse. If this is the case you can insert a 20 amp fuse..
If the fuse blows straight away it will mean that there is a short in the line anywhere between the motor and the battery. Check the wiring for heat if this happens as it could ignite the wiring.
Best Regards
Graham
I have recently completed a Fairey Swordsman following Bluebirds very helpful Plan for Beginners article.  I have fitted a Hunter Systems RS540-SF motor controlled by a Mtroniks Viper Marine 20 ESC protected by a 15 amp fuse running a bog standard 35 mm 2 bladed prop.  The Swordsman sails beautifully with a good turn of speed, however, after five or ten minutes running the fuse blows.  Is it normal for this type of set up draw in excess of 15amps or have I got something wrong?

Martin Bright
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inertia

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Re: Fuses Keep Blowing
« Reply #3 on: June 26, 2014, 09:32:02 am »

Graham and John both have a very good point about checking the shaft for friction etc. I have to say that a 35mm 2-blade plastic prop (probably an X35?) sounds excessive for that motor in that model. My prototypes both ran PropShop 1315 3-blade standard scale brass props. These are expensive, I know, but the reduced pitch places much less load on the motor while the increase in the number of blades seems to compensate to a certain degree. I used ACTion P80 (20A) speed controllers in both, running on 7.2v with 15A fuses, and never had a moment's problem with overheating or blown fuses.
Dave M
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RMB

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Re: Fuses Keep Blowing
« Reply #4 on: June 28, 2014, 02:08:27 pm »

Thank you Guys,
It looks as if I may have a motor/prop problem.  I will check it out and re align etc. and see if the problems goes away.  Dave, I don't want to go to the expense of buying a metal prop, do you think a 3 bladed plastic prop with 35mm dia and an 18mm pitch would be a suitable alternative?


Once again many thanks


Martin
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inertia

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Re: Fuses Keep Blowing
« Reply #5 on: June 28, 2014, 02:32:02 pm »

Who knows? It's not going to cost a lot to try it!
Dave M
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HUNTER

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Re: Fuses Keep Blowing
« Reply #6 on: June 28, 2014, 03:41:38 pm »

Dave is right, whenever I build a new boat I will go to the prop draw and pull out a prop and if not right then try another until I am satisfied with it. Then when I can afford it buy a decent one similar to the trial one - simples!
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reg

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Re: Fuses Keep Blowing
« Reply #7 on: June 28, 2014, 07:28:05 pm »

Replace fuze with a nail
that use to work in my old cars  :-)) O0 {-) %%

                                  Reg
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Netleyned

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Re: Fuses Keep Blowing
« Reply #8 on: June 28, 2014, 08:28:16 pm »

Four Inch or Six?
You probably had an Allegro {-) {-)


Ned
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inertia

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Re: Fuses Keep Blowing
« Reply #9 on: June 28, 2014, 11:00:56 pm »

From memory of my 1300 All-Agro (VAL 253L) it was the hydraulics which were the biggest pain. I think I had three new clutch master cylinders in the three months I owned it (while driving a loan Crystler 180 for two of those months).
Remove that nail and you'd have halved the value of the car.
Happy days!
DM
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