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.

Interesting to see so many variations on powering model boats. Most modern ESCs have overload protection.

As for me, I use the basic/minimal configuration for a single motored boat: one motor, one battery (using a BEC), no fuse.

This is my 50th year running RC boats and never had any issues other than the usual bad connections, dead battery, leaks, etc. I don't remember seeing anyone else where I run having fuses in boats. (Only exception is my 1/20 scale PT boat in which I have three fuses, one for each motor.)

Lew
Florida, USA

Hello Alessandro,
For larger ships and from a length of 90cm (35.5 inches) I prefer separate voltages.
For the sternwheeler I have 12 V= for the steamers, for the propulsion, as well as receiver as well as Leds each a 6V=, so that means one 12V= (3.2Ah) and 3x 6V= Batterie with 3.0Ah. This has been sufficient for me so far tiptop
The space is there and the few kilos do not make the roast greasy.
The distribution is the main problem here, because you forget certain electronic parts such as servos, relays, cables, switches, etc. which would then cause a small slant. But who do I tell!?!
This is well known to all here.
Please don't laugh, but the new self-adhesive lead weights for balancing the wheels are sheer madness and help the boats to take the "military stance" in no time!
Sleep well, Michel-C.

Hello Mike.

Thanks very much for your information.

What batteries do you use?
I don't think you'll use 12 volts for the receiver either (unless it goes through a BEC).

I will look more carefully at your naval models already published on this site, but if you want to add some images of your configurations (motor, ESC, receiver, batteries) to this topic, I would be very happy.

By bimetallic fuses do you mean those which, if passed through by too much current, heat up and therefore bend, opening the circuit and saving all the equipment? Did I get it right?


I take advantage of your intervention to open a parenthesis.
I often talk about current intensity and absorbed power as if they were synonymous.
I want to clarify so as not to make any mistakes.
It is obvious that the intensity of electric current and electric power are two different physical quantities. One is measured in amperes and one in watts.
But in the electronic and electrical engineering fields, at the same voltage (I repeat at the same voltage), they produce the same effects. Saying that a power supply (which has a stabilized 12 volt output voltage for example) is capable of delivering a certain number of amperes or saying that it can deliver a certain number of watts is the same thing.
At the same voltage, the Joule effects are the same, saying that the current increases is like saying that the power increases.
Everyone knows that in direct current (in alternating it is a little different) the power is given by the product of the voltage by the current, or by the resistance by the square of the current.

Ciao Alessandro,
I always use 12 V for my steamers, for this, like you, I always have two batteries, one for the receiver and the second for the motor. For larger fast models however I have 9V motors (St Raphael or Huntsman31 of my port).
Everyone makes his experience . . . I work with bimetal fuses . . .😉
Greetings from Switzerland,
Michel-C

If you want to get close to the 9V motor limit you could also use a 7-cell pack at 8.4V. You can get these up to 5A (5,000ma), and I've seen some approaching 6A.

Lew
Florida, USA

Hi Stephen, thanks for the answer, if you have an engine that supports 9 volts at most, you absolutely cannot put a 12 volt battery, because you would damage it.
If the ESC you have supports 12 volts, you could adjust the remote control stick so as not to exceed this threshold. But it is not always possible and it is a solution that I would absolutely advise against.
I absolutely don't like it as a choice.

I didn't understand why the 6 volt battery is no good.
Do you already have an ESC, do you know the parameters, at least the working voltage range?

Do you power the receiver via the ESC Bec, I'm asking you because perhaps the voltage on the Bec is too low.
In this case the right voltage could be 7.2 volts. But I always prefer to power the receiver independently with 6 volts and a battery only for the esc and motor. If you can, give us all the data of your electronic configuration.

Hi Lew, yes most motors are marked with voltage range but we thought it was strange to refer to a battery in that way! However mystery solved.

So the battery voltage needs to be about 6 to 8 volts.
Depending on what receivers you use, all the ones I use need 4.8 volts so allow for a small voltage drop in the esc to this voltage, 7.2 volts or a 6 cell battery would suit.

Many esc's have a maximum input of 6 or 7 cells, but there are also a few that work up to 12 volts or higher. As far as which voltage battery to use for the motor, I would be guided by the esc voltage limits.

If using Chinese esc's (which I do ) remember they must have their own units of current and power as they rarely translate to the ones we use!

Are you OK with the basic amps volts and ohms arithmetic? Not everyone is so don't be shy!

regards
Roy

Your question:
I have tug boat that has two 3/9 v battery’s the speed controller if I run 6 v will not power it can I run them with 12 v lead acid there joined to one controller [AND] on the motor it says 3volts to 9volts

The ratings on the motor (brushed?) is the nominal range for voltage to be applied to the motor. The lower voltage limit can be exceeded by the ESC when your control is set for running slow (lower voltage). The life of the motor will probably be shortened by running it over 9V. I would opt for a battery of 9V or less. (Those 12V lead acid batteries could actually be over 12V, possibly a little over 13V.)

Also, you need to know the ratings on the ESC before you go to to a higher voltage. Some will not handle 12V or more.

Lew
Florida, USA

on the motor it says 3volts to 9volts

No idea what he's trying to say.

Recently I tried to run a 650kv brushless on a single 6V SLA, soon learned I had to put two 6V SLA in series to get the motor to function off the ESC.

ALSO on here there was someone asking abt running a motor off one of those small rectangular 9V "transistor radio" batteries. 🤣

I'm glad I'm not the only one.
I have no idea what he said ....

Neither do I
Roy

Sorry Stephen, I didn't understand the question.

How many volts is the motor?