Battery safety switch

[Malcolm Fisher]

I haven't logged in for a while so have only just seen Andy48's response to my post about arming plugs and the failure of my ESC. If the extra wire length created by using one isn't an issue, why do all the people who seem to be knowledgeable about such things advocate lengthening motor wires rather than those between the battery and ESC? I have read several times that extending the battery to ESC wire is a potential cause of it overheating and thus failing especially during low throttle applications where the ESC switching is very rapid. That is why I suspect that the arming plug was the cause of my ESC being fried as I had been using a low throttle setting for much longer than I would normally. As for the soldering none of that was mine and the ESC had been in use for a few months with no problems before I introduced the arming plug. Perhaps someone with greater experience/knowledge will give an explanatory comment.

Malcolm

[Andy48]

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

Have you ever seen a 60 amp DC switch? See here:

Copper M10 studs, requires 19.5mm hole. Dimensions L 43 x W 46 x H 85mm.

[Andy48]

Posted by Malcolm Fisher on 04/08/2016 19:50:53:

I haven't logged in for a while so have only just seen Andy48's response to my post about arming plugs and the failure of my ESC. If the extra wire length created by using one isn't an issue, why do all the people who seem to be knowledgeable about such things advocate lengthening motor wires rather than those between the battery and ESC? I have read several times that extending the battery to ESC wire is a potential cause of it overheating and thus failing especially during low throttle applications where the ESC switching is very rapid. That is why I suspect that the arming plug was the cause of my ESC being fried as I had been using a low throttle setting for much longer than I would normally. As for the soldering none of that was mine and the ESC had been in use for a few months with no problems before I introduced the arming plug. Perhaps someone with greater experience/knowledge will give an explanatory comment.

Malcolm

14 gauge stranded copper wire has a resistance of 8 ohms per kilometre, 16 gauge 13 ohms per kilometre. You can do the maths to show that even an extra 10cm of wire will have a negligible resistance. I run all my planes using arming plugs, and the ESC never gets warm even with extended lead lengths. I also use in-line current sensing telemetry, which introduces a far greater resistance than an extra length of wire.

The fact that the soldering wasn't yours doesn't mean it was well done!

I do find your last comment insulting. How can you know what my experience/knowledge of electronics is?

[PatMc]

Posted by Andy48 on 04/08/2016 21:24:32:

Posted by Malcolm Fisher on 04/08/2016 19:50:53:

 

I haven't logged in for a while so have only just seen Andy48's response to my post about arming plugs and the failure of my ESC. If the extra wire length created by using one isn't an issue, why do all the people who seem to be knowledgeable about such things advocate lengthening motor wires rather than those between the battery and ESC? I have read several times that extending the battery to ESC wire is a potential cause of it overheating and thus failing especially during low throttle applications where the ESC switching is very rapid. That is why I suspect that the arming plug was the cause of my ESC being fried as I had been using a low throttle setting for much longer than I would normally. As for the soldering none of that was mine and the ESC had been in use for a few months with no problems before I introduced the arming plug. Perhaps someone with greater experience/knowledge will give an explanatory comment.

Malcolm

14 gauge stranded copper wire has a resistance of 8 ohms per kilometre, 16 gauge 13 ohms per kilometre. You can do the maths to show that even an extra 10cm of wire will have a negligible resistance. I run all my planes using arming plugs, and the ESC never gets warm even with extended lead lengths. I also use in-line current sensing telemetry, which introduces a far greater resistance than an extra length of wire.

The fact that the soldering wasn't yours doesn't mean it was well done!

 

I do find your last comment insulting. How can you know what my experience/knowledge of electronics is?

The cause of the problem isn't resistance, it's when the combined L & C reactance is at, or near, resonance with the switching frequency. This will result in a voltage magnification [ Q factor]. The lower the resistive reactance in the circuit, the higher the Q factor.

Edited By PatMc on 04/08/2016 21:55:17

[Allan Bennett]

My understanding of the long battery wire problem is that the wires can induce spikes of high voltage, which can damage the capacitors in the ESC, which will then allow the spikes to get to the electronic components and damage them. The damage may take some time to reveal itself, depending in the wire lengths and the quality and capacitance of the stock capacitors on the ESC, which is why you'll see many people saying they have "no problem" using long battery wires.

[Josip Vrandecic -Mes]

Posted by Derek Stevenson on 04/08/2016 14:45:43:

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.

By the way Derek, today is the anniversary of the death of the famous Merilyn Monroe , and I also wonder where are these beautiful natural beauty ? ....They are today mostly plastic and too '' elegant '' .. but no back .... new time, and new E-models...

All the best

[Biggles' Elder Brother - Moderator]

Andy, I don't think Malcolm was referring to you! I read his remark as meaning "someone more knowledgeable than himself"!
BEB

[Denis Watkins]

For information, commercial soldering of PCB is as we know magnificent due to the temperature controlled ovens used in the process. Some years ago, British Aerospace abandoned soldering wires in the looms of the Channel Tunnel Tractor Unit Control Panels due to breakages caused by vibration in use, and resorted to Crimping.

As we all know, when two wires are soldered together, they do become more brittle. The original soft solder has liberated some of the zinc during the heat/smokey process, and what is left is a harder more brittle metal.

Proof is when you come to Desolder the job, then it needs much more heat to separate the joint due to the higher melting point of the new solder material

Basics are, good clean metal at the joint, good strong heat, applied quickly and as efficiently as shaking hands can do the job, and an appropriate amount of solder, producing a nice brightly finished joint.

We know too the electrical properties of a poor joint are less than helpful to our hobby

[Dave Hopkin]

Posted by Denis Watkins on 05/08/2016 15:54:23:

Basics are, good clean metal at the joint, good strong heat, applied quickly and as efficiently as shaking hands can do the job, and an appropriate amount of solder, producing a nice brightly finished joint.

We know too the electrical properties of a poor joint are less than helpful to our hobby

The precursor to a good soldered joint (apart from it being clean) is a good mechanical joint to ensure the two metals are in very close proximity as solder works at molecular level and fuses into the surfaces of the parts

[Malcolm Fisher]

BEB hit the nail on the head. I have no knowledge of Andy's qualifications or experience. My comment was aimed at trying to get someone who had given me the idea that longer wires between ESC and battery wasn't a good idea. PatMc seems to hold that opinion and confirms what I believed was the cause. We'll never really know but from my, admittedly little, experience I will never again use one of those arming plugs. As someone with limited funds to spend on my hobby I can't afford to risk burning out another ESC.

When the incident occurred, the only change in my set up was the introduction of the arming plug. The model had been flown for over a year with no problems regardless of throttle setting with nothing going amiss. All had been OK with the plug in the circuit while I was only using the motor full out or off. The "fire" came about on the only occasion I used a low throttle setting for several minutes.

Malcolm