13 May
2014
13 May
'14
3:45 p.m.
"It is not uncommon for the electrolyte fro ma leaking battery to creep
along inside the insulation of one of the wires and corrode the wire
strands themselves. This can obviously cause an open-circuit, it can also
cause nasty intermittent faults."
This is what's known as "Black Wire Syndrome".. you may encounter it in a
variety of devices, but in my experience it's most commonly associated with
leaking Ni-Cad batteries.
The battery wiring looks OK from the outside, but the black wire is
completely corroded out inside the insulation jacket. There may still be
some electrical conductivity, but you'll never be able to reliably solder
or crimp onto the wire again.
Comes up when you're replacing internal rechargeable batteries in various
old gear. Had a case of it here, a couple months ago - in this instance, it
was the battery pack in an Epson PX-8 CP/M portable machine.
As an aside - for what it's worth, man oh man do those recent-generation
Ni-Cad batteries have some capacity! Every vintage unit I rebuild with new
cells will run for at least twice as long as the original spec. I think
this PX-8 goes for like 18-20 hrs at this time. Guess that's what you
expect, when a 3300 mA/h part drops-in for a 1200 or 1600 mA/h original!
On Tue, May 13, 2014 at 12:34 PM, Tony Duell <ard at p850ug1.demon.co.uk>wrote:
All *seems* to
be well now, other than the -ve wire from the battery
compartment needing replacing; the system powers up and seems to "work"
- I
It is not uncommon for the electorlyte fro ma leaking battery to creep
along inside the insulatio nfo one of the wires and corrode the wire
strands themselves. This can obviously cause an open-circuit, it can also
cause nasty intermittant faults.
It happens on cars too, the battery wires then gain resistnace so things
go wrong when the starter motor is used (t draws around 600A after all).
That can be 'intersting' to trace if you are not expecting it.
-tony