Black Wire Syndrome

Everyone is familiar with the typical white corrosion found on lead acid battery terminals.  But there is another more aggressive corrosion to deal with when using Ni-Cad batteries.  It has been dubbed “Black Wire Disease” or “Black Wire Syndrome” because it has a tendency to creep up the wire attached to the negative terminal on the battery.  In typical DC applications, this is the black wire.

There are several theories on the causes of this corrosion.  In general, it is a chemistry issue that is enhanced by various contributing factors including lug and wire plating, insulation materials, environment, and shorted cells or cell reversal.  The problem is well documented in the remote control airplane community because they have been using Ni-Cad batteries for some time now.

In the telecom world, the “Black Wire Syndrome” becomes the “Red Wire Syndrome” because as discussed in the previous post, telecom uses a -48VDC power source.  The red wire is tied to the negative terminal of a battery string and the black wire is attached to the positive terminal.  The problem with this situation is circuit breakers are installed on the negative lead.  If the circuit breakers are a short distance (electrically speaking) from the batteries, there is a potential for the corrosion to creep up the wire and into the circuit breaker.  The corrosion then renders the circuit breaker non-functional.

For additional information see: “Black Wire Disease – What’s the Cause?” by “Red” Schoenfield published in the June 2001 issue of The Flightline by the Propstoppers RC Club