Special "alligator clips" for connecting to batteries

Since I occasionally test camera batteries, when I saw these special alligator clips for connecting to them on Taobao, I decided to buy a couple for myself. But as it turned out, it wasn't that simple.


I don't run these kinds of tests very often, and in the past I've used various methods, from soldering to paper clips. The latter turned out to be the simplest and most convenient.


Then I came across these interesting clips, made specifically for this kind of use, and immediately thought, “I need some too.” I ordered them, they arrived, and the seller even wrapped them in a piece of Chinese newspaper :)


The product page offers two options: a regular Kelvin clip and these special ones. You can buy them as a pair or individually, though the per-clip price is the same either way.


They look thin and small, though there's no particular reason for them to be any bigger.


No complaints about the build quality. They're made of steel and painted afterward, and the paint job is neat.


The wires are meant to be soldered to the tab. The clamping contact is on the other “jaw” from the wire soldering point. At first I wanted to add a wire to connect the two halves, but eventually changed my mind.


Inside each clip is what's called a Pogo pin—a spring-loaded contact. To keep the battery under test from slipping out of the clip, one of the jaws has a rubber pad.


The connection is very simple: open the jaws, press them against the battery contact, and let go.


On the product page, everything looked really cool and convenient.


Broadly speaking, they looked just like the photo above when I tried them on a test battery.


But as the saying goes, “It looked good on paper, but they forgot about the ditches.”
The problem is that the clips have no insulation at all (apart from the paint), and with the contacts so close together, it's easy to cause a short circuit.


And even that wouldn't be a problem; I could just insulate them somehow, perhaps with heat-shrink tubing or electrical tape, although that had its own complications.
But all these problems pale in comparison with the resistance of these clips. Even that isn't so bad; worse still, the resistance varies widely, from a perfectly acceptable 0.2 Ω (0.1 Ω per pole) to a dismal 2–3 Ω.


Conclusion.
The idea itself is pretty good; they could even be used to measure voltage at some tricky test points.
But the high resistance completely defeats the purpose of battery testing. Most of it comes from the spring-loaded contacts, so there's no point in adding a jumper between the two halves of the clip.

So, unfortunately, this turned out to be a bust. If anyone knows of links to better-quality versions, I'd be very grateful.