Battery safety switch

[Attilio Rausse]

As others have mentioned, nothing other than physically (not electronically) cutting the main power feed to the ESC will guarantee that the motor is disarmed. So long as the power is there, there's the potential for the motor to start unexpectedly due to interference (no), faulty ESC(no), faulty receiver(no), incorrectly set fail-safe(yes), to name but a few.

Can you name a few more please.

[Attilio Rausse]

When talking about large electric models then I think that an arming plug could be quite dangerous because you are recommending that the power is on when you engage the device, you could have a very serious situation if the motor suddenly burst into life.

[Martin Harris - Moderator]

At the risk of repeating myself, the best way to ensure safety is to adopt safe practices - arm from behind the model, restrained appropriately and never reach through the prop arc. Arming plugs are great until something like a helpful bystander pops it back in to avoid you losing it, you forget to remove it, something shorts out the internal wiring etc. etc...most unlikely I admit, but we've all fallen victim to Murphy's Law so many times in the past!

Simple rule - use safety devices by all means but never rely on them.

[Andy48]

Posted by Martin Harris on 22/07/2016 15:18:58:

Arming plugs are great until something like a helpful bystander pops it back in to avoid you losing it, you forget to remove it, something shorts out the internal wiring etc. etc...most unlikely I admit, but we've all fallen victim to Murphy's Law so many times in the past!

I would be very very annoyed if anyone started fiddling about with my model. In any case, when I have finished flying, I put the transmitter down on the ground, remove the arming plug, clip it to my neck strap, then switch off the transmitter and remove the model from the field.

[Martin Harris - Moderator]

Of course you would - as would most of us. I'd be even more annoyed if I'd made an assumption that my safety devices were infallible and lost a digit through trusting my assumption!

Routines are wonderful until something unexpected interrupts them...

[MattyB]

I have been debating this very issue myself recently re: my Sebart Miss Wind. It is a stunning model, but there is one horrible bit of design on it - the battery hatch is secured by a tiny screw about 10mm behind the prop! This means once armed you have to get right up behind the prop with your screwdriver with over 1kw of power available from the motor... (Pic below is not my personal model, but you get the idea from the position of the thread behind the spinner):

At the moment I have a Dualsky ESC which does feature the disablement switch on a fly lead favoured by the OP. I am rather conflicted on this - it's very convenient and gives another layer of safety with the ESC deiabled even with the battery connected, but in general the quality of such switches is pretty low and I don't much fancy dead sticking it in due to a switch failure! I have witnessed an accident with an arming plug too though, so nothing is infallible - I think I may just fit a better quality switch and go with that.

[Martin Harris - Moderator]

Personally, I'd modify the hatch fastening arrangement.

[MattyB]

Yes, that's another good option but there is so little room around the motor at the front it's not that easy to do with a hook at the front, catch or magnet at the back type arrangement. Maybe I can get some magnets in up front, but there's not much room and I really don't want the hatch departing in negative g manoeuvres...

[Geoff S]

Could you replace the screw at the front with a vertical dowel and magnets or a screw in a safer place?

Except in certain models (perhaps Matty's Sebart is one?) I don't see how an arming plug is any safer than connecting the battery just before you fly. Indeed the arming plug harness illustrated by John F above is so close to the actual battery plug that all it does is add an extra complication.

Geoff

Edited By Geoff Sleath on 22/07/2016 20:01:19

[Former Member]

[This posting has been removed]

[Malcolm Fisher]

I used one of the Deans type arming plugs for a few months in an electric powered glider. All was fine as I only used the motor at full throttle to gain height then switched off and sought lift. On one occasion - the last time I used the device I struggled to find any lift and stooged around with the motor at a low throttle setting. After a while the model stopped responding to any control inputs and drifted away in a circular flight pattern much like a free flight model. When I eventually reached the plane smoke was pouring out of the canopy. This stopped when the plug was pulled. The inside of the model was badly scorched and the ESC a mass of charcoal. I suspect that the extra wire length between battery and ESC was the cause and have never used the plug since.

Malcolm

[Andy Butler]

Be very careful here guys - In all of the ESC's I've used the fly lead that has a switch attached isolates only the BEC output not the power to the motor. It allows you to switch off power to the receiver and servo's, hence why the switch is usually small as the currents are not very high. With the switch in the off position, power to the motor is not switched off and the motor could suddenly start for any number of reasons.

[Andy Butler]

posting from work so I always have to press the button twice to get it to do anything so double posts - apologies.

Edited By Andy Butler on 04/08/2016 13:05:49

Edited By Andy Butler on 04/08/2016 13:06:05

[Christopher Long 1]

Any good reason that this from HK should not be used?

**LINK**

Chris

[Derek Stevenson]

What about the good old oily dirty ic engine, lots of mess but much safer? Also all the fun of getting it started and keeping it running. The note from the ic engine when in flight is sooooooooo soothing.

[Derek Stevenson]

What about the good old oily dirty ic engine, lots of mess but much safer? Also all the fun of getting it started and keeping it running. The note from the ic engine when in flight is sooooooooo soothing.

[The Wright Stuff]

Posted by PatMc on 20/07/2016 23:16:28:

Posted by Spikey on 20/07/2016 18:45:50:

Question arises from a combination of arthritic fingers, tight XT60 connectors and an earnest wish to avoid digit damage ...

I find these a boon. Also worth buying some spare adapters in the same order - but at the moment the tool with adapters are listed at less than half price !

Have to say I'm a bit surprised that Pat's solution has been largely ignored. Solve the original problem (difficulty in separating the plug and socket) rather than introduce new problems and more complexity. You really don't need plugs, switches, or yet more wiring...

I've successfully used an even simpler version of this. Drill a small (1.5 mm) hole in the centre of the plug and another in the socket plastic, well away from the metal contacts, and then use a pair of external circlip pliers to gently and effortlessly lever the plug out of the socket. Just insert the tips into the holes. Works every time - no more wiggling and pulling! Plus the long handle places your hand further from harm...

 

Edited By The Wright Stuff on 04/08/2016 15:01:38

[Engine Doctor]

Posted by Derek Stevenson on 04/08/2016 14:45:41:

What about the good old oily dirty ic engine, lots of mess but much safer? Also all the fun of getting it started and keeping it running. The note from the ic engine when in flight is sooooooooo soothing.

With you on that one

P.S It also stops my Tinnitus ............but possibly helped cause it in the first place

[Dave Hopkin]

Posted by Engine Doctor on 04/08/2016 16:07:24:

Posted by Derek Stevenson on 04/08/2016 14:45:41:

What about the good old oily dirty ic engine, lots of mess but much safer? Also all the fun of getting it started and keeping it running. The note from the ic engine when in flight is sooooooooo soothing.

With you on that one

P.S It also stops my Tinnitus ............but possibly helped cause it in the first place

Tsssh you and your 19th century technology..............

[Andy48]

Posted by Malcolm Fisher on 22/07/2016 20:47:27:

I used one of the Deans type arming plugs for a few months in an electric powered glider. All was fine as I only used the motor at full throttle to gain height then switched off and sought lift. On one occasion - the last time I used the device I struggled to find any lift and stooged around with the motor at a low throttle setting. After a while the model stopped responding to any control inputs and drifted away in a circular flight pattern much like a free flight model. When I eventually reached the plane smoke was pouring out of the canopy. This stopped when the plug was pulled. The inside of the model was badly scorched and the ESC a mass of charcoal. I suspect that the extra wire length between battery and ESC was the cause and have never used the plug since.

Malcolm

The extra wire length between the battery and ESC could not have caused it to fail. There will be a slight increase in resistance in the wire to the ESC, this will have the effect of reducing the current to the ESC.

Also if this could cause the ESC to fail, then what about using an older lipo with an increased internal resistance? That too would cause the ESC to fail.

No, plain and simple the ESC failed due to either dodgy electronics in the ESC, too much power going to the motor, or some dodgy wiring/ soldering to your arming plug.

[Andy48]

Posted by Christopher Long 1 on 04/08/2016 14:20:46:

Any good reason that this from HK should not be used?

**LINK**

Chris

Yikes! Nooooooooooo!

While that switch is labelled heavy duty, and has XT60 connectors on it, there is no way a switch that size could handle 20 amps let alone 60 amps.

Notice there is no mention of how much current it will handle, my guess is a max of 5 amps.

[MattyB]

Posted by Andy Butler on 04/08/2016 13:04:10:

Be very careful here guys - In all of the ESC's I've used the fly lead that has a switch attached isolates only the BEC output not the power to the motor. It allows you to switch off power to the receiver and servo's, hence why the switch is usually small as the currents are not very high. With the switch in the off position, power to the motor is not switched off and the motor could suddenly start for any number of reasons.

Yes, I have wondered about that, it's one of the reasons I am not keen on my current setup with the Miss Wind. When I plug the battery in with the flylead switch in the off position I get no tones from the ESC/motor; they occur only once I switch it on. However, I am not using the ESC BEC (red wire has been removed, I am using a separate SBEC which livens up the RX and servos as soon as the battery is plugged in). Question is does that mean the motor is powered or not when the battery is plugged in with the flylead switch off? Can probably test with my multimeter, but it will mean some fiddly disassembly - I may just continue to treat it as "live" at all times and seek an alternative canopy latching solution.

[MattyB]

Posted by Andy48 on 04/08/2016 17:57:40:

Posted by Christopher Long 1 on 04/08/2016 14:20:46:

Any good reason that this from HK should not be used?

**LINK**

Chris

Yikes! Nooooooooooo!

While that switch is labelled heavy duty, and has XT60 connectors on it, there is no way a switch that size could handle 20 amps let alone 60 amps.

Notice there is no mention of how much current it will handle, my guess is a max of 5 amps.

Seconded, that unit is a crime against safety - I cannot believe they sell it with no warnings that it is not to be used between a battery and ESC; newcomers will look at those connections and just assume it is fine to do so. Madness!

[John F]

Posted by Andy48 on 04/08/2016 17:57:40:

Posted by Christopher Long 1 on 04/08/2016 14:20:46:

Any good reason that this from HK should not be used?

**LINK**

Chris

Yikes! Nooooooooooo!

While that switch is labelled heavy duty, and has XT60 connectors on it, there is no way a switch that size could handle 20 amps let alone 60 amps.

Notice there is no mention of how much current it will handle, my guess is a max of 5 amps.

I am not being pedantic or challenging but how do you know that the switch cannot handle anywhere near the 60 Amps that the xt60 connectors can?

Edited By John F on 04/08/2016 18:56:36

[Dave Hopkin]

Posted by John F on 04/08/2016 18:48:30:

Posted by Andy48 on 04/08/2016 17:57:40:

Posted by Christopher Long 1 on 04/08/2016 14:20:46:

Any good reason that this from HK should not be used?

**LINK**

Chris

Yikes! Nooooooooooo!

While that switch is labelled heavy duty, and has XT60 connectors on it, there is no way a switch that size could handle 20 amps let alone 60 amps.

Notice there is no mention of how much current it will handle, my guess is a max of 5 amps.

I am not being pedantic or challenging but how do you know that the switch cannot handle anywhere near the 60 Amps that the xt60 connectors can?

Edited By John F on 04/08/2016 18:56:36

Looking at the wire gauge used it doesnt look like something I would be happy to use for 60A !!!!