Model Boat Mayhem

Mess Deck: General Section => Model Boating => Topic started by: tt1 on February 08, 2010, 06:58:28 pm

Title: Fuse rating Advice needed
Post by: tt1 on February 08, 2010, 06:58:28 pm
Hello all, can anyone please advise how to fuse (especially the rating) an Msonik4 25amp esc and an MFA combi drills torpedo 500 motor using a 6volt battery. I am assuming that there should be fused protection. also where in line should the fuse be? between esc and battery, between battery and motor or etc etc.
You can tell by the very nature of the question electronics isn't my forte.
                              Cheers, Tony.
Title: Re: Fuse rating Advice needed
Post by: grasshopper on February 08, 2010, 07:12:28 pm
The fuse should be fitted between the motor and the ESC. that was if it gets weeded up or the shaft locks it protectes the ESC from getting frazzed. If the ESC also supplies the power to the receiver, at least that way you'd still have steerage.

Rating wise on the information you've supplied would be difficult but 20A would be the max fuse I would put in line - if the ESC is rated at 25A there's margin for error!
More info on hull type/design peformance and prop info would help.
Title: Re: Fuse rating Advice needed
Post by: PMK on February 08, 2010, 07:36:57 pm
Tony, do you have an ammeter?
If it's a digital meter, you need to connect its red lead to the 6v battery positive terminal, then connect its black lead to the positive terminal at the motor. Now connect the battery negative terminal to the negative terminal on the motor.
Making sense so far?
Make sure that your meter is set to the Amps range, then pop the model in a tub of water and, while the motor/propellor is spinning, take a note of the meter reading. Let's assume that your particular setup is pulling 5 amps with the motor under load. All you need do is to remove the two ammeter leads and stick the 5A fuse in place of. As a rule-of-thumb, you might want to opt for a slightly higher value, say 6amps, or even 7.5amps.
A picture says it far better than I can, so you might want to point your browser here...

http://www.action-electronics.co.uk/home.html

Click 'Diagrams and Articles', followed by 'Wiring Diagrams', then select any of the links. From within you should be able to glean the needful.
Good luck.

Incidentally, if your ammeter is of the analogue flavour, then you'll likely need to reverse the red/black leads.
Title: Re: Fuse rating Advice needed
Post by: malcolmfrary on February 08, 2010, 07:45:25 pm
It all depends on what you are trying to protect.  My inclination is to have the fuse as near the battery as possible, in the positive lead.  This protects against the possibility of a fault inside the ESC (not unknown) and problems with the ESC wiring.  The ESC should carry its own protection against problems coming from the motor.  If the fuse blows and steering is lost the chances are that you wont notice, as steering doesn't happen with a stationary boat.
Title: Re: Fuse rating Advice needed
Post by: tt1 on February 09, 2010, 02:42:46 am
It all depends on what you are trying to protect. 

Thanks for responding guys, and being honest re the point you made Malcolm, I don't know what I should protect :embarrassed: don't know why but the esc was foremost in my thoughts, and my only consideration of possible cause was the prop being jammed or shaft seizing. Thanks for the link info PMK.
                                     
         Regards to all, Tony