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Terminally ill Terminal

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MrAl

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Hi,

I use those quick disconnect terminals a lot, the kind that mate with the opposite gender and are often found on mid sized Lead Acid batteries like 7Ahr sizes. I believe they are sometimes called "F" connectors. They push on and pull off.

My problem is that no matter what terminal i use, the wire always manages to break off eventually.
I found that this is caused by the wire entry point, where it enters the terminal top where it is crimped or soldered.
The wire used is almost always stranded because it has to flex a little.

There are several different kinds of terminals in that they have different shapes where the wire enters the terminal top. Most are crimp type, and you crimp the wire strands themselves (the copper strands) and anther crimp for the insulation. These kind are better than the kind that dont have that second crimp for the insulation, but they are still not quite good enough.
The type that solder or if you just decide to solder the wire on that's even worse as the wire breaks at the point where the wire enters the solder.

What i did was create a terminal with a large metal protrusion at the top, where you can wrap the wire around it at least once before soldering the end. This means the insulation plays a bigger role in absorbing some of the flax and some of the strain if the wire is pulled a little. It ends up looking funny, but it works.

What i was wondering is if anyone has seen anything like this for sale around somewhere? I would like to buy some nice commercially made units if possible. I recently bought some larger ones that i can modify myself, but i would prefer to get something ready made and nice and strong.

Thanks :)
 
Fast-on terminals are usually used for batteries. Now, I think you have a wire problem and not a terminal problem. Take a look at the wire and count the number of strands. A lot of times there is a 7/ and one higher, The 7 strand wire is not really flexible, but it is stranded. Just like the wire Radio Shack sells is cooper and not tin plated. Both will bite you.

Get a good quality flexible stranded wire. If you wand a few feet of wire, try these guys: **broken link removed** The 16 AWG Belden wire is composed of 19 strands of 29 AWG wire. when I did automation panels, I liked the 7 strand stranded. So, not all wire is created equal. Try finding these specs at most places. You have stranded, or solid. Try PVC insulated 600 V oxygen free annealed copper with tin plate 18 AWG, 16/31 or whatever.

Now, if you really want it to flex get some Litz wire: https://hflitzwire.com/litz-wire?gclid=CIGnqc31gb8CFaZ9Ogods0sAcA Think like what phono cartridges were wired with.

Th next thing you can do is use the adhesive shrink tubing on the ends.

Way back when, I think AMP made a really cool ring terminal that was insulation displacement. I don't know if I have any unused ones around anymore.
 
Hi,

You're absolutely right that better wire would help, but i happen to also know that the wire i am using works pretty well when the solder or crimp joint itself is not stressed but the stress is all pushed back onto the wire itself.

To illustrate, think about a wire the solders into a hole in a regular single sided PC board. You can push the strands through, solder it onto the copper clad, enough solder and you're all set. But the problem is that the now solid solder does not allow the wire at the very joint to flex, so it gets stressed too much and eventually breaks.
Now think about this....instead of drilling just one hole in the PC board drill three holes. One hole goes where the copper is, which is the 'normal' hole, the other two go right in line next to the first hole, so they are all drilled more or less along a line. The second and third holes are drilled slightly larger diameter, to accommodate the insulated part of the wire, and the first hole is just enough to take the strands. Then thread the wire through the 3rd hole, then up through the 2nd hole, then finally through the 1st hole with the copper, then solder it as usual.
The result is that when we pull on the wire now, the first two holes and the insulation take the most stress, and that relieves the stress on the joint itself immensely. Something like this could last a long time whereas the one hole scheme could break very soon with a little flexing.

Now apply that same idea to a terminal, which also has a wire attached, and you get the idea. Relieve the stress on the joint itself and it lasts a lot longer.

Since i posted this thread i found some interesting terminals, interesting because they mount into PC boards! Yes, they mount through holes drilled in a PC board, so i could mount them to a small PC board and then run the wires as described above for the PC board. I think this would make them last a lot longer even with the wire i have now. But i also like the idea of getting some better quality wire, which i really should do too anyway, and i only need a short length so it should not be costly as long as i can get smaller quantities.
 
I don't like poking wires in a board. Concord Electronics makes solder cups with pins which are really nice, but Concord is hard dealing with. High minimums.

How many times do you replace a battery anyway. Every 2 years? I'd like to see you get better wire.

Post your "interesting" solution.
 
Hi,

Well it's not about replacing a battery. That only has to happen every couple years or so. My Fios battery had to be replaced every 1.5 years or so though.

This is about USING the battery for various purposes, where you connect the device when you have to use the device, then unplug it when done.
In particular, i've wired up my cordless drill to the 12v battery. The drill plugs into a connector, the connector plugs onto the battery terminals using the 'terminals' we are talking about. Moving around a little with the drill means the terminals get stressed...not much, but enough to break the wire now and then. It's not too often but fixing it means breaking out the soldering iron and heating it up, then resoldering the wire.

The gimmick is just to solder more metal to the connector itself, then use that extra metal to hold the wire. It can be made in various shapes, so that you can wrap the wire around it one or two times before soldering the very end to the connector top side.
I can take a picture a little later on, but it's not pretty :) It's just functional, for now, until i get better terminals.

I also found some heavy duty terminals that i think i can use. These have a 'rolled up' sleeve for crimping the wire, and unrolling that metal will yield a nice strip of metal that is already part of the terminal body. That means more metal to mount to, which will probably work pretty well. These things set me back $6 for quantity 7 terminals so i hope they work. I picked them up locally so no wait for shipping.

I'll try to get the pics a little later today. I should have taken a pic of a broken one too but didnt do that and it's 'fixed' now, but just imagine a seven (or more) strand wire with only two strands left soldered to the terminal, the rest flapping in the breeeze :)

I thought about other ways to handle this too, such as installing better terminals on the battery. I heavy duty connector would be nice, with a mating connector to the drill, but then i'd have to do all my 12v batteries and i dont want to have to do that. I also use a "jump pack" sometimes where the drill plugs into that via a cigar lighter plug connector.

Thanks for any ideas or suggestions. I like the extra multi strand wire suggestion, and i have such a wire around too already. It's ultra flexible so that will be part of the new terminal 'upgrade'.
 
Use an Anderson Connecter. That's what they are designed to do: **broken link removed**

Even so, you can always make an adapter that takes the Anderson and adapts it to the Faston (I'm assuming).

Test Probe wire is really flexible. I used that to replace the OEM wiring on some POP-UP headlights in the early 80's.

So, I think your trying to use something in a way that it's not intended and therefore it will break.
 
Hi,

Well we are humans and humans are always inventing new ways to do things.

Here are two pics of the terminals showing Fix1 and Fix2. Fix1 (right, both pics) was done by just soldering the wire at a 90 degree angle after wrapping the copper strands around the barrel of the terminal. Fix2 (left, both pics) was to use a small piece of steel, soldering that to the terminal first and then running the wire (with insulation) through the large eyelet, then soldering the end to the terminal or near the terminal.
Even with Fix1 the setup lasted much longer than with a normal crimp or double crimp type, and i expect Fix2 would last a very long time because that's got a nice grip to it, large enough for thumb and forefinger. It's ugly though as you can see, although i could have done a better job if i wasnt in a hurry that day.
 

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Hi,

Well we are humans and humans are always inventing new ways to do things.

How true:)!
In search of a connector which combines high current capability, ability to cope with stranded wire, and durability, I found the following:

**broken link removed**

Yes, its pricey, so here's a cheaper version:

https://www.ebay.co.uk/itm/like/301...f11=ICEP3.0.0&ff12=67&ff13=80&ff14=108&ff19=0

I seem to remember, from one of your posts, that you do some machining yourself, MrAl. In which case you would be able to cut a slot in a suitably sized bolt to make such a connector for yourself.
Here is yet another supplier of these things:

**broken link removed**
 
Crappy copper wire too. And you missed a strand. Hate when that happens. Nice handles.

Yes, lamp cord and i was in a hurry because i had to use the drill :)

I am posting another solution i just did about a half hour ago in the next reply. This one uses one of the new connectors i picked up locally.
It's not too bad i guess, but always open for new ideas.
 
Hi,

Well we are humans and humans are always inventing new ways to do things.

How true:)!
In search of a connector which combines high current capability, ability to cope with stranded wire, and durability, I found the following:

**broken link removed**

Yes, its pricey, so here's a cheaper version:

https://www.ebay.co.uk/itm/like/301...f11=ICEP3.0.0&ff12=67&ff13=80&ff14=108&ff19=0

I seem to remember, from one of your posts, that you do some machining yourself, MrAl. In which case you would be able to cut a slot in a suitably sized bolt to make such a connector for yourself.
Here is yet another supplier of these things:

**broken link removed**


Those are a little big but yes i can scale it down.

More to the point though, i guess what you intended was that i use that in combination with the Faston female connector? The Faston connector is the main point of the thread, i need to be able to stick it on various size batteries, which have the male connector type on them.
But your idea could be combined with the Faston connector itself i think, so i am still going to think about this.

Here are a couple more pics more to the point of what i am after. Other ideas are also welcome of course, especially ones that involve high durability.

The one with the big metal tab soldered to it is the second type of fix, the one with the more normal looking side entry is the newest (third) type of fix, where the wire enters into the sleeve that normally gets crimped onto the insulation or wire, and then wraps around the body of the Faston by going behind it first (still with all insulation) and then coming around to the front, then the stripped end gets soldered to a little tab that was bent up from the original unmodified connector where that tab originally formed part of the sleeve. Id didnt know i could bend that up until i took the plastic off of the Faston (this one was completely covered in plastic insulation).

The third pic here shows the two connectors from the edge so you can see how the wire wraps around the metal before the end is soldered. This provides much higher durability.

If they made connectors like this they could do a much better machining job.
 

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Yes, I was thinking of leaving the Faston in place all the time, since the wire only breaks due to the repeated action of pushing it on and pulling it off. With the Faston in place always, with the free end of the wire connected to it left bare, you could stick the bare end into the split bolt connector. That way your wire would last much longer.
 
Hi again,

Well actually the wire can move about a little because it connects to the portable drill. The drill runs off the battery, and connects to the battery with an adapter that has a cigar lighter jack on one end and the Faston connectors on the other end. When the drill is used normally, the wires will move around a little although not a huge amount, so it has to be a little rugged.

The only way i can stop the wires from moving would be to mount the adapter right to the battery body, with a strap or something, but i didnt really want to have to do that. I believe with the right connector design it can work pretty well even if it doesnt last forever.
 
Hi again,

Yes it is a right angle Faston, but i dont use it the way it is supposed to be used as you can see in the pics, i run the wire with the insulation still on through the sleeve, then run the wire behind the Faston, then back up around front (so now the wire make 1 turn around the body of the Faston) and then finally bend the stripped end and solder it to the metal. I dont crimp the wire like what is normally done either, because that would defeat the purpose of wrapping the wire around the body.

Another thought was to use heavy gauge copper wire, like 14 or 12 gauge wire, to form a loop with maybe twisted ends, one lead longer though sticking out of the twisted end. The long lead gets soldered into the Faston, the wire from the device (with insulation) gets wrapped around the loop once or twice, then the stripped end soldered to the Faston on the top of the sleeve (not a right angle Faston) . Now when the wire is pulled the loop gets pulled by the wire with the insulation on it wrapped around the loop wire, and the loop pulls on the Faston but in line with the line of pull when it is normally pulled off, so all of the wire stress gets distributed around the loop where it bends.
I'll draw a quick pic up.

I can not see your link for some reason, is it working ok? I'd like to see what you are talking about there as that sounds interesting too. Keep in mind however that this is not just about pulling on the wire by accident to remove the Faston, it's also about durability even when not trying to remove the Faston, when the wire has to move around a little with the human operator while the battery stays flat on a work bench or table. I have enough wire length so it's not too bad, but it will still have to move around a little.

In the drawing, the 12 gauge wire is soldered to the Faston first, then later the 16 gauge device wire is wrapped around that and then soldered to the body of the Faston. There is a little slack left in the wire so the part that is wrapped around the 12 gauge wire takes all the stress.
 

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Hi,
I had a similar idea to that in your TerminalDrawing-1.gif. It was to braze or epoxy on handles to the female Faston connector, as ullustrated in the attached image. Two alternatives are shown. The LHS image has a cross-member fixed to the flat side of the female slot;), of a stiff material, say steel. You use your fingers on the handles to push the connector down & to pull it up. The RHS image has a plate with a flange, with an inverted L cross-section stuck to the female connector. You grip the flange to push down or lift up. In both cases there is no strain on the wire and so it should last indefinitely.
 

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I use a similar method to MrAl's. A thick wire is soldered to the connector and its free end wraps around the flexi-wire sleeve:
Termination-with-stress-relief.gif
 
Hi,

Oh yes, some very good ideas coming out here now!

I think i will have to go with a combination of the stress relieve and the handles. The handles are good for easy plug in and unplug, and the stress relieve for relieving the stress on the wire when it moves around during normal use.

Usually these things are used for batteries where the battery is more or less stationary and so is the wire. You pull them off, put a new battery in, then push them back on. Five years later you have to do it again.

This application is so different because it is so much more dynamic than that. Not only does the battery have to be disconnected and reconnected every so often, the wire moves around a little too. One time the wire had been broken through several strands near the Faston connector, just a few strands left to carry all the current.
 
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