HI Dave and Alan,

Thanks to you both for the replies and advice. it all started when I got hold of the Action Electronics wiring diagrams for individual models which showed a P95 fuse unit on both the battery side and the motor side, then realised in all of the diagrams I looked at the motors were brushed and as you say Alan they don't draw a lot of current, the P95 is limited to a maximum of 25 amps anyway. My Turnigy D3536/6 1250KV draws a maximum current of 34 Chinese amps and I am trying it on a Hobbyking 50 Chinese amps boat ESC (the only one not on backorder after a two week wait) so I was looking for some additional protection. I thought of putting an inline fuse holder in the live wire from the battery to the ESC maybe with a 30 amp spade fuse.

If and when I finish the Waveney I will certainly be doing some regular checks on how everything is performing.

Cheers Shaun

HI Shaun and Alan
Fuses are best placed close to the battery as this is what delivers the power and will cause damage if there is a short or the motor stalls.
Whilst a fuse between the ESC and brushed motor will protect the motor and wiring after the fuse, any problem with the ESC will not be covered and high currents could be drawn if there is a short. Fortunately the MOSFETS in modern ESCs usually fail open circuit so the risk is possibly low.
Brushless motors require all three wires connected and will run very rough and draw lots of amps should one wire become disconnected. Using a fuse in any one of the wires would be a very bad idea as current would continue to flow in the other unfused wires.
Like Alan I run my brushless without fuses and make sure the ESC is of sufficient Wattage to meet the demands of the motor. I agree double the actual amps drawn is usually sufficient to meet the demand. I concur re the Chinese amps comment, the size of wires they use should usually give a clue as to the true figure.
Provided you check all remains cool at first installation and check after each sail there should be few problems. High power and fast speed require that you complete a regular health check on you set up, bit like a plane pilot checking everything is fully functional before take off. Bad or loose electrical or mechanical connections need to be fixed before you put in the water.
Regarding high power fuses they are available via car accessory shops and I did install a 50amp fuse in a brushed model with two motors, with seperate 25 amp fuses for each ESC/Motor.
With the high power available from LiPo batteries perhaps we should be fitting a fuse? I believe racing boats have an external emergency connection that can be pulled to cut the power.
Be good to hear others views and experience, especially with the higher power setups.

Mmmm, I do have fuses in a few of my scale models with brushed motors, but most of these motors don't take a lot of amps, 15 to 25amp car fuses.
The boats I have with brushless motors have no fuses, as a lot of these motors take a lot of amps I don't know what type of fuse you would use.
Myself and all in our club try to make sure that the ESC is man enough to handle the amps that the motor will draw.
Bear in mind that Chinese amps don't seem to resemble ours.
If we had a motor that had a rating of 80 amps we would be looking at an Esc of 150 amps
On the first sailing the boat needs to be brought in at regular intervals so that the temperature of the ESC, motor and batteries can be checked.

It is sometimes a good idea to get a few different sizes of plastic props, start with the small ones and work your way up while checking temperatures against performance, a bit of a balancing act really.


If you did fuse the three phases of the motor and one fuse popped while the motor was running, I think the motor might still run on two phases and perhaps do the motor some damage, the motor will not start on two phases, but once running could continue.
Perhaps someone more knowledgeable than me could throw some light on this.

Just my thoughts Shaun

Alan