You do it your way and I will do It my way. I'm passing on what is successful for me. I'm done with this topic!

Lew
Florida, USA

Hi Lew.

Secondo me, le trattazioni "Motor to Power" e "Fuse position Rttl installation mod " di questo forum andrebbero "fuse".

In my opinion, the "Motor to Power" and "Fuse position Rttl installation mod" discussions on this forum should be "fuse". (in Italian "fuse" is merged)

Excuse the play on words, but these two topics actually discuss the questions about the usefulness of putting a fuse and where to position it.
We also talked about the different positions of fuses in a simple circuit.
I expressed my opinion in the fourth message of that topic and subsequent ones, but there were important contributions from ColinH, Dgoss999, GregHiltz, Rowen and RodC, which I took into serious consideration.
In addition to the position, the intervention thresholds and intervention times were taken into consideration.

I received important suggestions on the choice of the intervention threshold and I thank everyone who gave them to me.

Now, by reading well (carefully) all the messages in the two topics, everyone can get an idea of whether or not the fuse is useful in an RC circuit (even a simple one), and how to position it.
Therefore I invite all those interested in this topic to read the other one too.

For example Rogal118 (in his tenth message) drew a truly logical conclusion.

In my opinion, in this context, it is preferable to give advice not by referring to a particular model or situation, but in general.
Not everyone knows, for example, whether or not their ESC is protected from surges (it may not be). You may have received the ESC as a gift, you may have forgotten whether your ESC is protected or not, or you may never have known.
But even if you are sure that your ESC is protected from overcurrents, I still prefer not to have its protections intervene (especially if it is an expensive ESC) but to intervene first and protect it with a fuse.
Furthermore, we said that the fuse can save not only the ESC but also the motor.

For these reasons I suggest the fuse even in simple circuits.

In general I reiterate that putting a fuse (or two) costs nothing in terms of money, weight and work, so: why not do it?

My comment on the need to fuse a SIMPLE circuit (receiver, servos, ESC, battery, motor) might be better explained in the sketch I provided here.

If the fuse is placed between the battery and the ESC (most fuses are at the source of the power) it seem to serve no purpose except save the ESC which likely has an overcurrent protection. I see no reason to add a fuse to a simple circuit.

However, if you are running other items, horns, lights, etc., off the main line (input to the ESC), that is a different issue and I can understand the need to add a fuse (or more fuses) for the current draw / circuit protection.

Remember, the use of an ESC is two fold. To supply receiver power (~4.8-6.0V) and motor power (0 to XX V).

I only mention this as the majority of my boats don't have other taps off the source (battery power) voltage.

Con-FUSE-ing?

Lew
Florida, USA

Thanks Hermank, your suggestion is very clear and precise.

I want to follow your method, in particular also the indications that ColinH and DGoss999 gave me (even if they differ a little from each other) in the topic of this forum "Fuse position Rttl installation mod".

Despite the small differences, the methods are based on considering the motor and ESC nameplate values, one being more conservative than the other.

I have adopted an empirical method that is too conservative and therefore I risk blowing the fuse long before the current is dangerous for electronic devices.
I had measured the currents involved and doubled the values. I don't think it's good.
The value I chose for the fuse (20 amps) is probably too low.
The fact that it has never burned so far is not significant.

To adopt the ColinH method, I must take into account the rating of my motor and my ESC.

Sorry but I wouldn't consider the value declared by the (unknown) manufacturer of my ESC at all. I don't believe it supports such current intensities at all.

I will only consider the engine.

GRAUPNER Speed 600

Operating voltage range 3.6...8.4 V
Diameter 35.8mm
Free shaft length 8.7 mm
Case length 57 mm
All-up weight, approx. 235 g
Maximum efficiency 69%
No-load current drain (A) 2 A
Charging rate at max. efficiency 12 A
stall current 85 A
Permissible motor direction R and L
No-load speed 18200 U/min
Nominal voltage 7.2 V
Shaft diameter 3.17 mm

The important value is this: stall current 85 A

I could use an 80 amp fuse, if I understood your teachings correctly.

For the moment I don't intend to reach such high values so I will put a 30 or 40 amp fuse and do some tests (in the future).

I intend to measure higher currents, under more severe conditions, but I can't do that with my multimeters that go up to 10 amps max. I'll borrow a clamp meter.

I thank everyone for their informative contributions and for sharing their experiences.

Amigo italiano
I always is fuses 2 A less than the maximum of the ESC.
If the ESC is 10 A I put fuses in of 8 A
Doing this you never have problems
Hope this helps to avoid trouble

Hello Hermank, Belgian modeller friend.

I think you're right to use fuses.

Out of curiosity, can I ask you if you remember what ampere threshold they have?

Alessandro sp Bongorno amigo Italiano
I always use the Marx decaperm motors. Unfortunately they are hard to find. All of my models are between 115 and 125 cm long and always put fuses in between and never had esc fuming😴

Hi Lew.

Protections are generally used for accidental failures or errors.

If you've never had any problems it means you've been lucky or you're very good.
I believe the second, you are very good.

Indeed, choosing the ESC, batteries and motor with the right values ​​(the result of the modeller's experience) and using quality equipment (from guaranteed brands) could avoid any inconvenience.

You're right about that, but what harm does putting a fuse or two in?
They cost very little and weigh very little.

If they are placed by an inexperienced model maker who uses poor quality materials (like me, for example) the fuse will certainly be useful, even essential.

If a very expert model maker puts them in, who uses good quality materials (like you, for example) the fuse will stay there, good, good, without ever being used but it won't hurt.

I would say to an even more inexperienced modeler than me: follow Lew's advice on choosing the motor, ESC and batteries, but put a fuse anyway.

I add one last thing: an expert modeller can choose and calibrate all the devices in the best way, so that he will not have problems during navigation, but it may happen that he carelessly causes the positive terminal to touch the negative terminal directly. This is a rare occurrence with current connectors, but it could happen. In that case 20 cents and a few grams of fuse will save 50 or 100 euros of equipment.

Even if the devices already have protection against short circuits, I prefer to intervene first.

Sorry, I just didn't understand what the "military stance" is.

Hello Mike.

Ok, now I understand correctly.

The question of the positions of the weights and how to secure them well is very important in sailing.

Do you use a buoyancy reserve in your models?
On mine, unfortunately, I didn't have enough free volume under the bridge to be able to do this. I don't need to tell you, you will have already seen it for yourself.