Bending uninsulated terminal is safe?

[Camillo]

A friend of mine is an electrician and works on ultralights electrical systems. He is very well known for his competence.
He looked at my main power cable (for battery and/or alternator power) 6AWG uninsulated terminal which I terminated on my own and told me that it is not safe to bind the terminal part of the terminal to match the bus bar. This will lead - he says - to breaking along time.
My doubt is that Van's suggests to do this on battery + uninsulated terminal with Odyssey instructions.
Does anyone know if this is a common and safe practice or not?
Thanks.
Camillo

 

[kevinh]

He looked at my main power cable (for battery and/or alternator power) 6AWG uninsulated terminal which I terminated on my own and told me that it is not safe to bind the terminal part of the terminal to match the bus bar.

Hmmm. I don't quite follow - can you rephrase this question? Is he saying that the metal tab on the terminal will crack due to vibration.

 

[Camillo]

Yes. Exactly. I installed a 6AWG uninsulated ring terminal. This terminal has to be screwed to tha main bus copper bar. Due to the difficulty to bind 6AWG cable, I preferred binding of approx. 45? the ring part of the terminal, in order to let it stay flat with the bar without spring action.
Thanks.
Camillo

 

[Radomir]

Just to make a small ESL correction -- Camillo means BENDING the terminal (not binding)

I've seen it done, but I can see how it could raise some concerns..

 

[kevinh]

I've seen it done, but I can see how it could raise some concerns..

Oh! Bending - I was confused about the binding part! I've seen it on a friends RV with many hundred of hours, though I bet you'd want to be careful to have a curved edge on whatever tool you use to bend it.

 

[Camillo]

Yes, bEnding. A little vocal can make a lot of difference...
I bent it gently with a pair of pliers. I did the same for Van's terminal which goes to battery +, as per drawings.
I hope they both will last a few hours...
Thanks.
Camillo

 

[flion]

As mentioned, a radius on the bend is necessary. The other factor is support for the cable, which is true even for an unbent terminal tab; they tend to break at the cable side of the tab. After crimping my terminals and making sure they were oriented correctly, I soldered them and made sure there was a well-formed solder fillet (it should be concave, not convex). With that and good support for the cable, I'd not expect it to break.

 

[SteinAir]

Of course straight is preferred, but the good or bad of "bending" (and how much you can bend it) really can depend on the types of terminals you use. If they are good quality aviation type terminals, they will have a brazed seam and will be of good solid construction. Many auto type terminals are simply folded up tin with no brazed seam...aviation terminals are (or should be) tin coated copper. Quite a lot heavier, a bit more expensive, but all around pretty darned good. I think a lot of people have some small bends in them and I wouldn't get overly concerned about that...you really have 2 layers of metal in the good quality terminals.

My 2 cents!

Cheers,
Stein

 

[Bob Axsom]

One Bend is OK

When I read that you bent the terminal with pliers I cringed a bit because sharp bends and tool marks can lead to cracking over time. If you bend the terminal with some radius in the bent and you do not bend it back (work harden it) I wouldn't sweat it at all. I would never solder the wire to the terminal if I could avoid it (even with SN63 solder, concave fillets and feathered edges to the base metals) because it directly affects the flexibility of the wire in the area where it is most vulnerable.

Bob Axsom

 

[az_gila]

Stein... is this true for...

...
...you really have 2 layers of metal in the good quality terminals.

My 2 cents!

Cheers,
Stein

...a heavy terminal that goes on the battery (see post #1)?

They really seem to be a single piece of metal to me (AC Spruce terminal)....

This commercial one may be two layers, but it seems to come with a built in stress point where the tube was squished flat....

B&C seems similar to Spruce -

 

[L.Adamson]

I would never solder the wire to the terminal if I could avoid it (even with SN63 solder, concave fillets and feathered edges to the base metals) because it directly affects the flexibility of the wire in the area where it is most vulnerable.

Not too long ago, there was a thread here, debating the pros & cons of solder.

I'm very aware of the possiblities of "wicking" solder back into the wires from the joint; and that flexing can break the wire, since it's multi-strand flex ability is removed.

However, I did silver solder my large terminals to the battery, alternator, and starter motor, after crimping. These heavy wires are well supported, and several layers of shink tubing cover the solder joints. I also kept the heat at the terminal, so that the solder does not wick back into the wire strands.

I feel better about this, because of an electrical failure experienced in another aircraft, where the wire became loose in the terminal fitting. It did a lot of electrical arching, before becoming loose and blackened.

When it comes to small wires, some of mine are soldered with heat shrink for support, while others are just crimped.

L.Adamson --- RV6A

 

[SteinAir]

Gil is quite right....I got a little tongue tied between my brain and hands, and apparently didn't quite finish what I intended to say...in fact just as Gil stated (and I wanted to, but didn't), there is a big difference between aviation and auto grade terminals as shown in his fine bit of research. Buy from a reputable place and you won't have to worry!

Cheers,
Stein

 

[az_gila]

Thanks Stein...

Gil is quite right....I got a little tongue tied between my brain and hands, and apparently didn't quite finish what I intended to say...in fact just as Gil stated (and I wanted to, but didn't), there is a big difference between aviation and auto grade terminals as shown in his fine bit of research. Buy from a reputable place and you won't have to worry!

Cheers,
Stein

...I was trying to show the difference between "good" ones and commercial ones...

Definitely buy from a reputable source (skip Home Depot), but Stein forgot to mention he is also a source for good terminals....

http://www.steinair.com/terminals.htm

 

[Camillo]

I bought my uninsulated terminals from both B&C and Steinair. I don't remember which of those I used (if from B&C or from Steinair). Anyway, they were identical (as per first photo shown).

I bent them with pliers (I have its mouth covered with insulating tape) and it really took little effort to bend it (I think one may bend it with hands on the angle of a wodden table). Also, I bent it only once.

I can deduce that this wouldn't effect its strenght, even though not bending would have been obviously better! But if I did not bend it, I would have had a hard curve on the 6AWG cable with quite spring back force. I think that this would have been far worst!

Camillo

 

[Rivethead]

I had a 90* bent terminal on my Cessna's + battery connection. It broke right along the crease after some time and looked to my untrained eyes to be caused by metal fatigue. It wasn't so bad that it broke, it was when it broke. Who's the guy that says the worst things happen at the worst time? I'm so bad with names.

 

[mburch]

Strain relief

I was worried about battery cable terminals breaking, so I made sure to use adel clamps at both ends. That way the clamps will take the strain instead of the more fragile terminals. This is not a great photo, but you can just barely see the adel clamps at the top and bottom of the main battery positive cable:

I figure stuff like this is cheap insurance for later on down the road.

good luck,
mcb