Failed battery hack- analysis?

Werner Almesberger werner at
Tue Oct 11 00:41:54 EDT 2011

cenobyte at wrote:
> So you mean to say that headphone wire is a legitimate electrical
> connector?

Sure. You're not running excessive currents or high voltages
through it, so it should be quite adequate.

> Does it matter that I touched both color wires of each one to
> the terminals?

Hmm, not entirely sure what you mean. As long as there's one
wire from + to +, the other from - to -, and none between +
and -, this should work, though.

> and should I have used electrical tape instead of
> scotch tape?

The tape may be the problem. Not the kind of tape but whether
it actually pushes the exposed wire sufficiently against the
contact. Rubber bands may be more reliable.

Likewise, wire apparently wound around the Ben's battery
terminals can in fact have an air gap. If you can arrange both
wires such that they are under light mechanical tension, that
may help to make the connection more reliable.

> BTW the reading on the battery is 3.9-4V

That should be plenty. You can also verify with the voltmeter
that the voltage doesn't drop excessively when reaching the
Ben's battery terminals. (E.g., because of some problem with
the cable or because the battery is unhappy.)

- Werner

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