How do you clean your alligator clips?

[MrAl]

Hello there,


This sounds like a very strange and simple question im sure, but when i was charging some Li-ion cells
and looking into the series resistance vs time issues i ran into the problem where my clip leads were
a surprisingly very high value. In fact, one of them was up to a full 1.000 ohms! That's way too high
especially when charging cells because the circuit (two wires only) slows down a bit even with only
an extra 0.1 ohm lead resistance.
I started testing several of my multitude of clip leads (one alligator on each end) and found that many
of them had much higher resistance than expected, like 0.08 ohms and even that is higher than it should
be.
Investigating a bit further, i found that one of the main causes was that the alligator clips were partly
oxidized so the teeth do not make good contact. Using a very small file, i cleaned the teeth carefully
and then retested and some of the resistance readings went down to as low as 0.01 ohms. That's a
really big difference. I dont want to move to a four wire system as it is more of a pain and really
should not be necessary, so i need a way to clean the alligator clips without removing any of the
plating or whatever they put on the surface to reduce oxidation. i would even consider some sort
of plating even if it isnt too complicated.

What isnt a good idea so far:
Obviously an eraser does not work as the teeth will dig up the eraser and it will just ruin it.
I used a file, but that removes plating.

Any other ideas?

[Robert Reed]

I have that problem too. I use a small cylinder shaped wire brush to clean the teeth. Also if the clips have an insulating boot, they can restrict movement somewhat as far the clips closing tight and the clips seem to lose a little tension over the years. One thing I do to alleviate that is to squeeze the clip into the jaws open with one hand. Hold it there and squeeze the jaw tips partially shut with the other hand. This improves grip strength. There seems to be a wide variety in the quality of these gator clips and I have found Mueller to be the best, but no matter what brand they still require periodic cleaning ( maybe once a year).

[MrAl]

Hi Robert,


Small cylinder shaped brush? Where did you get that?
I have a small round one but it wont fit in between the teeth too well, and the bristles get
folded over really fast with those things.

[gerty]

You can go to Walmart or a gunshop and get a bore cleaning brush. They are available in brass, bronze, or copper bristles. the daimeters vary from .180" on up to .500.
The smallest being for a .17 caliber, the largest for a .45 caliber.
The biggest problem I encounter with jumpers is the wire where it connects to the clip, repeated flexing causes some of the strands to break and after a while you only have a few left.

Edit: the brushes are typically about 2-3 inches in length.

[haklesup]

In most cases these clips are made of a cheap base metal plated with Chrome. While Chrome resists oxidation, is a hard surface to wear and has good conductivity, I think that it would be very easy to wear a thin (read cheap chinese) layer away and expose the base metal which is likely to oxidize easily at the jaw surface.

Better quality clips would have a thicker final plating and a quality base metal alloy. If you want the best connection, you could consider gold plating the clips but that may be overkill. Brushing the jaws is obviously the cheapest solution.

For me its failure of the wire where it crimps to the clip or banana plug that is my biggest problem.

[Robert Reed]

MrAl
I had scrounged these from the maintenance dept. where I used to work. Down to my last two and don't know what I will do when they are gone, but Gertys reply sounds like a good idea. Like others My lead wires periodically break off inside the insulation and are hidden from view. Biggest headache here is the 5-10 minutes wasted to figure out what you did wrong in your test setup! If you have a hot solder iron sitting on your bench at the time - then no problem its a one minute fix.

[Bob Scott]

For me its failure of the wire where it crimps to the clip or banana plug that is my biggest problem.

About ten years ago I found that Radio Shack started to manufacture their clip leads without using solder like they used to. The crimps looked like someone without the right tools made them by squeezing the joints with pliers instead of a crimper. After a while they get intermittent or resistive as the copper wire oxidizes. You have to solder them yourself.

[jwax]

Exactly Bob! The wizard marketing guru at Radio Slack came up with that concept to encourage hobbyists to buy a soldering iron from them to fix their alligator clips! Jenius!

I like the gerty idea- buy a bronze or brass bore cleaning brush from a sporting goods store or gunshop. You can even chuck it up in a drill for fast teeth cleaning!

[MrAl]

Hi again,


Oh yeah, i have them break off at the solder interface too, but what i do is pull on the wire
and if it stretches then i know it is broken off inside and needs fixing again. I've had this
happen quite a bit too, but there are two different (at least) types of stranded wire, those
with some number of strands and those with more than usual strands for the same AWG.
The type with the larger number of strands does not break as fast as the wire with the lower
number of strands, so replacing them with the good wire is a good idea too.
They also make special test lead wire if you are interested in fixing all of your leads (i use the
cheap wire but most of them are made from the stranded wire with the larger number of strands).

The silicone wire is really nice for this kind of thing, but i think you have to buy a huge number of
feet to get it, and it's not cheap. It is something to consider though if you really use jumper
wires a lot.

I check all my RS jumper wires (he he) for non solder type, and solder them myself. The last
bunch i bought were already soldered, which was a surprise for me.

Another thing to be careful about is when fixing the lead by soldering the wire right to the very
end of the clip. It's a better idea to solder the wire about 1/4 inch past the very end and then
actually crimp the wire insulation with the little crimp on the end of the clip. It doesnt break
as fast that way either.
The interface between wire and clip is more intricate than it looks. We want the wire to be
solidly attached yet we want some flexibility so it doesnt break fast. It's not too hard to get
that combination if you have a good full inch of length to work with but when you only have
that 1/4 inch it's very hard. Another idea is to solder the wire about 1/4 past the very end
and then wrap the insulation around the last 1/4 inch with strong 'coat' thread. That holds it
securely but allows for some flex before it starts to break.
Of course the more exact way to do it is with a spring...
The reason it breaks in the first place is because of the bend in the wire at the very end. Limit the
bend angle and it lasts a lot longer before it breaks. If the wire goes through a spring and the spring
is mechanically attached ridgedly to the very end of the clip, the spring limits the bend angle which
means it lasts a lot longer before breaking inside the wire. I imagine it would take quite a bit of
time and dedication to solder little springs to the end of all your clip leads though.

Anybody ever try metal cleaner used for fine objects?

[yusha]

I have used a Dremal rotary brass wire brush which works well.after cleaning with brush ,spray with contact cleaner and they will stay clean longer.