Break-out Blade for Easy Battery Current Measurement

To meaure battery current you have to break the circuit and insert an ammeter. This is fiddly as you have to ensure the meter probes contact the cells without them springing out.

Here is an easy low cost way to solve that problem.

Two core wire, small piece of plastic, small piece of self-adhesive copper tape.

Watch the video, and read below for EXTRA TIPS how to make a VERY thin flexible blade, or a very STRONG but thicker blade (these tips are not in the video, they only in this Instructable).

Cut a small bit of thin plastic to this shape - I used plastic from an old milk carton.

Stick the copper tape to both sides the plastic blade. It doesn't matter if it overlaps.

Cut the balde to shape and trim the corners so that it will fit in the battery holder.

Do a final resistance check to ensure the sides are not shorting together.

Strip the wire ends and solder to the blade. Check to ensure there is not a short circuit of the wires.

If you want a really thin blade, you can omit the (milk carton) plastic and simply stick the tape back-to-back, but only remove the backing paper from one strip. The backing from the other strip will insulate the two sides. The blade is not as strong, but very thin and flexible. To prevent the wires pulling the sides apart you should use thin flexible wires.

If you need a rugged blade and have the space, you can use a small piece of double-side printed circuit board (PCB).