Switches and speed controllers

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24 January 2021 at 10:33 #4710
gecon
Participant
@gecon
Is a fuse box as good as a switch?
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24 January 2021 at 10:33 #93364
gecon
Participant
@gecon
Hello all, having got as far as installing R/C gear and batteries in my Fisher 34 I need to air a thought or two yet again, sorry!

I have refered to DM's very informative tech-tips about 'electrickery' installations etc.

I assume that it's OK to use the fuse holder and fuse as a 'switch' in the '+' wire instead of installing an actual switch in this '+' wire -from the battery to the Sp controller?

Removing the fuse is not quite as simple as flicking a switch but I don't want to use up even more space 'under the bonnet'. Switches are not as reliable as removing a fuse I suspect?

The speed controllers (2 of them in fact) are Graupner Navy 30A. with BEC. I've removed the BEC wire from one of them. As DM writes, the switch on the Spd controller controls the signal to the Rx, it does not switch off the power supply from the battery to the controller.

I read elsewhere that winch servos (3 of them) may on occasions require more current than the BEC can supply. I don't think more than 2 winches will be moving simultaneously so I expect the BEC will be OK.

If I notice trouble here, I have dedicated a Rx battery available which can be installed later -and remove the other BEC supply so that controllers only supply the drive motor and bow thruster, not the rudder servo and 3 winches.

Any comments/advice/suggestions are welcome.

George
24 January 2021 at 12:30 #93365
Fred wooley
Participant
@fredwooley76212
Personally i would use a switch main reason for this is simple the more you put in and pull out a fuse you will not only weaken the contacts but they will also widen so to speak and cause power failure simply in mind not worth the hassle of not fitting a switch

Stavros
24 January 2021 at 13:23 #93366
ashley needham
Participant
@ashleyneedham69188
For boats with aircraft esc and no esc switch, of which I have a few, I find that simply plugging in the battery and unplugging it does the trick

As Fred says, contacts would be weakened by constant unplugging of fuses. A switch would be best, and although a bit bulky, Halfords do a 16A rated switch which should handle main battery power (when switched on, bearing in mind it would not be switching max current at the start).

Ashley
24 January 2021 at 16:25 #93370
Malcolm Frary
Participant
@malcolmfrary95515
Fuses generally need more space – you have to get your fingers around them As said earlier, regular insertion and removal does cause the contacts to fatigue.

Switches have two current ratings of interest – one is the current that can be switched, the other is the current that can be carried before the contacts start to heat up. Usually the figure quoted on the box is the switching current.
24 January 2021 at 16:28 #93371
gecon
Participant
@gecon
Oh,… OK then, off to the equivalent of Halfords tomorrow then. Unless I go for unplugging the Tamiya gold plugs which are accessible but a bit stiff to drag out and that will also tend to weaken something too! I'll have look for two good switches.

Many thanks for your valued opinions,

George
24 January 2021 at 19:15 #93373
Colin Bishop
Moderator
@colinbishop34627
I agree with the comments about plugging and unplugging fuses.

As far as a switch is concerned the Halford's types are big chunky things and rather crude. It's worth doing a bit of research on whether you can get something smaller that will handle the continuous current drawn from the battery. It is often possible to conceal a switch somewhere on deck within a box or a fitting of some kind that lifts off. I do this with most of my models so I don't need to remove the superstructure at the pond which tends to lead to things breaking off!

Component Shop do a ranges of switches which may be worth looking at but there are other sources.

**LINK**

If the toggle on a toggle switch is too long you can shorten it with a saw!

Colin
24 January 2021 at 19:45 #93374
gecon
Participant
@gecon
Many thanks again chaps,

Small-ish Comp' shop switches seem to be around 10A. My local equivalent of Halfords has a switch which looks very similar in size and rated at 30A. Seems to be about same size 20mmX11mm. Don't think it's necessary to order from UK to get this job done. I pay online and they chuck it in the boot when I drive to the car park! A spray of antibac and we're in business!

Post a photo of the 'crouded-upper-cabin' in a few days.

George
30 January 2021 at 09:57 #93449
Richard Simpson
Moderator
@richardsimpson88330
Don't forget of course that there are also in-line fuses that are held together by an internal spring and a bayonet type fitting in the holder. These can be disconnected by simply pushing and twisting the two halves of the casing that does not put any wear or tear on the contacts.

While I completely agree with the thinking that you need an additional switch to the one fitted to the speed controller as that does not disconnect the motor, I have always been happy to first switch of the receiver power with the speed controller switch then simply unplug the battery for complete isolation. If it is a Tamiya type of battery then simply unplug the white connector and if it is a lead acid then I remove the positive lead and put a cover on the terminal.

Edited By Richard Simpson on 30/01/2021 09:58:11
30 January 2021 at 10:15 #93450
Colin Bishop
Moderator
@colinbishop34627
The in line spring contact fuses are fine for low power applications but have been known to overheat where the contacts meet if the current is too high as the ends are rounded and don't provide a very large contact area.

In my smaller smodels I use the surface mounted cradle spring fuses but I don't think you can really beat the automotive blade type which have a large contact area and can pass high currents either by direct connection to spade connectors or within a purpose made holder. I don't like the idea of constantly removing and replacing any type of fuse. They and the holders are not designed for it and will become loose plus it can put a strain on the connecting wiring. If you need to turn things on and off use a switch – horses for courses.

Where batteries are installed permanently in the boat I always fit a switch immediately downstream of the battery in the positive lead to isolate anything connected to it.. This can mean two switches if you have a separate RX supply. The switches can be mounted anywhere convenient and don't have to be right next to the battery.

My two Fairey boats are fitted with LiPos which I only put in the boat when running it. They are otherwise kept in a fireproof pouch inside an old biscuit tin!

I like to be cautious!

Colin
30 January 2021 at 17:08 #93457
gecon
Participant
@gecon
Well the latest regarding my switches is that the Speed 400 motor on the bow thruster seems to have a short in it. Rather than spend more time on this, I have 'moved on' by going to plan 'B' which was established in case the thruster gave trouble at some stage. The motor is still down in the bilges and not connected to anything at all.

I now only have the drive motor connected to a single Graupner Navy 30A spd-controller. I am using the BEC wire to power the Rx. The two 5000mAh (to port and starboard) batteries are also lurking down there, but only one is connected to the system.

The other battery is standing by for use when needed. Later I will make up a Y-lead and have both batts into the system.

A 30A fuse is just downstrem of the battery in use and 'before' the switch which is in the red wire and has 30A rating. I will probably fit a 20A fuse to system before lauchday.

All above is I think approx what you are all more or less in agreement with?

George

Edited By gecon on 30/01/2021 17:14:18
30 January 2021 at 18:09 #93458
Colin Bishop
Moderator
@colinbishop34627
Never expect us to all agree George – we all have our little foibles…

Colin
31 January 2021 at 04:21 #93464
gecon
Participant
@gecon
I at least agree with myself -I think. Great to read the different ideas for a safer installation.

Again, many thanks to all,

George
31 January 2021 at 08:06 #93465
Richard Simpson
Moderator
@richardsimpson88330
i think it is important that we can all show mutual respect for each other while having our different approaches to things. If that is the case, and it certainly is on this forum, then anyone can feel free to put forward their own suggestions on anything.

In most cases there simply is no right and wrong, just different ways of achieving something, although I think we would all agree if we saw something potentially unsafe.

I completely agree with Colin that a switch and a fuse is the 'best' installation but installation restrictions might also need to be considered. I have had a fishing boat that was given to me now around ten years ago. It is fitted with a lead acid battery and has a switch on the speed controller. It does not have a switch on the battery, which is incredibly difficult to get to. Consequently it remains connected 24/7 but has never been a problem in all that time. I have considered adding a switch or making it easy to disconnect but, as the hull is crammed with electronics I haven't got the courage to dig in there!

Edited By Richard Simpson on 31/01/2021 08:06:50
31 January 2021 at 08:58 #93467
ashley needham
Participant
@ashleyneedham69188
Wot Richard (and Colin) says.

I despair on other forums at the level of animosity sometimes that greet suggestions and remarks.

Everyone should be free to offer suggestions and indeed to disagree with those other suggestions.

Ashley
31 January 2021 at 10:06 #93469
Colin Bishop
Moderator
@colinbishop34627
Yes, we can all offer our pennyworth but basically it is on a 'best endeavours' basis and the enquirer can make whatever decision suits their particular situation. Sometimes, as Richard says, you are faced with a fait accompli!

Several different views are very useful in highlighting potential risks and we can often all learn something new.

Colin

Edited By Colin Bishop on 31/01/2021 10:07:19
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