Keep an Eye on Those Ring Terminals

[az_gila]

Originally Posted by rvbuilder2002

Actually I think a lot don't. It seems new builders are getting talked into it all the time, so I think it is worthwhile for it to be mentioned.

On the other hand, getting a good crimp on a 6 to 2 gauge wires without a special tool is difficult and prone to errors.

Heck, even Vans shipped starter cables with loose crimp connections at one time -

https://www.vansaircraft.com/pdf/batterycables.pdf

Keep the terminal screws tight and heat shrink the soldered joint and it will be OK...

[rvbuilder2002]

Originally Posted by az_gila

On the other hand, getting a good crimp on a 6 to 2 gauge wires without a special tool is difficult and prone to errors.

Heck, even Vans shipped starter cables with loose crimp connections at one time -

https://www.vansaircraft.com/pdf/batterycables.pdf

Keep the terminal screws tight and heat shrink the soldered joint and it will be OK...

Gil, what exactly is your point?

I doubt that the wire on the terminal that started this thread is 6-2 gauge.

That fact that a mistake can be made by a human when crimping only?

The point is a properly done crimp is totally sufficient. Improperly using solder (proper soldering takes a lot more knowledge and skill than crimping) can cause a lot more problems than it solves. I have seen it first hand. Even on heavy gauge cables.

[az_gila]

Originally Posted by rvbuilder2002

Gil, what exactly is your point?

I doubt that the wire on the terminal that started this thread is 6-2 gauge.

That fact that a mistake can be made by a human when crimping only?

The point is a properly done crimp is totally sufficient. Improperly using solder (proper soldering takes a lot more knowledge and skill than crimping) can cause a lot more problems than it solves. I have seen it first hand. Even on heavy gauge cables.

My point is that solder applied correctly is acceptable, and crimps are not as infallible when made in a garage environment, especially for the large wire sizes.

I did assume it was a heavy gauge wire from the amount of heat generated and with no breaker trip. How many solder blobs/drops can a small gauge soldered wire terminal create?

Quite a few amps must have been involved and the wire itself did not fail.

We also don't know if the failed terminal was on the protected side or the bus side of the switch and/or breaker.

[Toobuilder]

In this case, it was the protected (load) side. 14 AWG.

[az_gila]

Originally Posted by Toobuilder

In this case, it was the protected (load) side. 14 AWG.

Thanks, at 14 g all of the solder must have drained onto your leg...


The other interesting question about the use of switch screw terminals is the use of lock washers.

Some switches come with them and other seem to not use them. Since the lock washers are usually steel, I presume that they don't fully deform against the copper terminals and can actually be re-used, but haven't found any literature confirming this.

Did your terminals have lock washers?

[Bavafa]

Originally Posted by rvbuilder2002

Gil, what exactly is your point?

I doubt that the wire on the terminal that started this thread is 6-2 gauge.

That fact that a mistake can be made by a human when crimping only?

The point is a properly done crimp is totally sufficient. Improperly using solder (proper soldering takes a lot more knowledge and skill than crimping) can cause a lot more problems than it solves. I have seen it first hand. Even on heavy gauge cables.

What are the downside to solder after crimp if it is done right?

[Ironflight]

You wick solder into the wire, making it stiff. Where the stiffness ends, and the flexible wire begins, you end up with a spot where the wire flexes with vibration, and can eventually fail. This really isn't an issue with solder joints in the middle of wires, but can create broken wires at terminals, where one end of the wire is constrainted, and the unconstrained wire can move.

Soldering can be done right, and is used throughout aerospace - but crimps are designed to last forever without soldering.

This is a case where adding suspenders to your belt can actually hurt you.

BTW Mike, when you said solder was dripping out from under the panel, I figured it was just another typically warm day in the Mojave....

[gasman]

Originally Posted by Bavafa

What are the downside to solder after crimp if it is done right?

I don't like crimps. I also don't like eyes and screws.... I like push-ons. They do give a superior electrical bond pressure at contact point.

So I do crimp.... but as I do it, I push a small tail through the crimp tube to extend 1/16th or so on to the flat. I heat the flat with a solder iron from under side and touch a SMALL amount of solder to the tail. It never wicks even to the center of the crimp tube.

I heat shrink all connections.... The original plastic collar was removed at the start.

The next time you go to solder a connection, see how much solder you need to apply for it to drip in a 1G situation. I expect it to be over 10 times the amount needed for a proper connection.

It was not the solder, It was the application. Like all the other skills needed to build your A/C, take a little time to learn how to do it right..... But wait, did I do it right?......

[JanRV6UK]

Not all crimps are created equal

http://www.ebay.co.uk/itm/like/17142...s=true&ff13=80

or ...

http://www.ebay.co.uk/itm/like/35155...s=true&ff13=80

PIDG ... Expensive but very good when used with the right tool ...

[vlittle]

Originally Posted by vlittle

Conventional strobe circuits are notoriously hard on switches. Any kind of resistance will cause thermal runaway. Sounds like you've experienced this. You may have to replace the switch as well.

There was quite a bit of discussion on this about 8 years ago on the Aeroelectric list.

Cheers,

Update: Thermal runaway is caused when there is a negative correlation between circuit voltage and load current. Most switching power supplies, including strobe power supplies, exhibit this effect.

For example, at 12 volts, the circuit may only draw 3 amps;
At 6 volts, the circuit would draw twice the current, 6 amps to deliver the same power.

Now put a resistive bad connection or cheap switch in series and the power dissipation of the bad connection quadruples (proportional to load current squared). The heat generation further degrades the connection, increasing the current and so on.

The terminal is toasted and the switch is toasted.
Terminal: http://www.vx-aviation.com/rv-9a/pho...IMG_0935_2.JPG
Switch guts:http://www.vx-aviation.com/rv-9a/pho...IMG_0956_2.JPG