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Author Topic: All Artisans of the Black Arts  (Read 2736 times)

RAAArtyGunner

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All Artisans of the Black Arts
« on: March 17, 2015, 03:32:15 AM »


To all the Artisans of the Black Arts I have a dilemma.

This battery pack was giving problems and upon closer examination, found that the black (-) wire had the dreaded green corrosion and was only attached by a couple of threads.
Remember reading on other threads that the solution is to replace the entire wire, in fact, I will replace both black and red wires with new wires.

My dilemma, am not sure if the corrosion will not reoccur at a later date and what preventative action to take if any.
Recall something about a leaking battery causes the problem, if so then should the battery pack be consigned to the bin.

.
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Danny

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Re: All Artisans of the Black Arts
« Reply #1 on: March 17, 2015, 07:27:16 AM »

"Black wire disease" happens mainly when ni-cads have been left in a "flat" or low voltage condition.  The resulting corrosion from cell leakage, causes poor current flow and makes the copper strands brittle causing eventual breakage.
This seems to be accelerated by the proximity of salt water!  The only safe way to 'cure' it, is cable replacement.  You may also find that the battery pack is also defunct!
A good explanation of cause and effect is given here -
http://www.barbadosrc.org/misc/blackwire.php


The corrosion can and does travel some distance from the battery pack, so don't let it get to your receiver  <:( 
Cheers
Danny

derekwarner

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Re: All Artisans of the Black Arts
« Reply #2 on: March 17, 2015, 08:19:25 AM »

 ok2...... well they say a photograph never lies..... :D

1. the +RED wire appears to have been recently soft soldered to the battery + tag
2. why not consider scraping, cleaning & washing the -BLACK battery tag with Hcl or Chloride solution [400 g/l] , then resolder the cleaned & fluxed wire...

As you know....I have near no knowledge of these black arts.......so suggest you wait for a person more competent in this craft O0..... Derek
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inertia

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Re: All Artisans of the Black Arts
« Reply #3 on: March 17, 2015, 08:49:02 AM »

I wouldn't recommend any first aid to the existing cable - chuck the whole lot away, including the connector. It's not as if they are an expensive item. Black-wire rot seems not to occur in tinned cable. Checking the battery pack seems a very sensible thing to do, too. Charge it up slowly then test the voltage across each cell - you can usually push a steel pin through the covering to act as a probe. Duff cells will show less voltage than the rest.
DM
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malcolmfrary

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Re: All Artisans of the Black Arts
« Reply #4 on: March 17, 2015, 09:04:43 AM »

Since the corrosion will have traveled up the wire, the only cure is to "mend it with a new one".  Having less and less metal in the lead over time will have restricted the battery's current delivery capability, and the battery might well be a good way along its natural lifespan anyway, so a new lead will certainly improve matters, but might not reset performance back to day one.
I have in the past tried reconnecting such wires, stripping back the insulation and cleaning the corrosion off.  This invariably just leaves a pile of bits of thin wire because the surface corrosion has gone most of the way through each strand.  Repeating the process takes you far enough along to convince you that it is an exercise in futility.
Stopping it happening again is mostly a matter of sealing the ends so that air (especially damp air) cannot get in, but if the new wire lasts as long as the old one, this might not be a real concern.  Any sealing obviously needs to happen after the soldering.
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roycv

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Re: All Artisans of the Black Arts
« Reply #5 on: March 17, 2015, 09:11:00 AM »

Hi all, most if not all of the battery packs available come with a plastic shrink outer cover.  Whether this does not allow the 'leakage' to disperse I do not know.
However I have had more than a few black wire wire encounters over the last 40+ years.  I used to think it was the soft soldering of connecting wires but I agree with the explanation mentioned before.
If I have a suspect pack I carefully cut off the shrink wrap so that it can be re-used.  Cut and file off the black wires and using a 100 watt soldering iron re-tin the battery connection point and replace the wire.
I use a multi meter on volts across the terminals and put the cell or battery on charge.  I check each cell for the voltage across it while on charge.  The nominal 1.2 volts rises to 1.4 to 1.55 during charging.
Any voltage higher than that means that the internal resistance of the cell has gone up (Ohms Law) which also means that the capacity of the cell has gone down.
If left in place it will discharge before the other cells in the battery pack and get a reverse charge as the rest of the cells discharge.
I do not think it is worth buying a new cell so I just reduce the number of cells in the pack.
If the cell seems OK then re-assemble put the outer covering back on and use electrical tape to secure it.
I have batteries of 4 and 5 cells all useful in their own way.  The 4 cell battery runs the Rx and servos.

Another point worth mentioning is looking into the back of the Transmitter if you have one with separate cells.  You can get a green corrosion of the cell contacts, this appears to start from the most negative end as well.
If you have this problem the green corrosion removes the plating of the contacts.  I clean this off chemically using a hard water scale remover, soak it into some kitchen tissue to stop it spreading.  The inter connections could be replaced if one knew where to get them but sometimes an old Tx yields them up.
For badly corroded contacts I have found that a small compresseion spring can be cut into 3 or 4 coils and 'screwed' around the contact which can then make the electrical contact to the battery.
Best practice is to take the batteries out of the transmitter when not used for a prolonged period or try and remember to keep them charged up.

Hope this helps.
regards Roy
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Bill D203

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Re: All Artisans of the Black Arts
« Reply #6 on: March 17, 2015, 12:48:44 PM »

The pack looks old to me. Time to buy another pack. 1200 amh is a bit old hat now days.
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RAAArtyGunner

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Re: All Artisans of the Black Arts
« Reply #7 on: March 18, 2015, 12:01:19 AM »

"Black wire disease" happens mainly when niggards have been left in a "flat" or low voltage condition.  The resulting corrosion from cell leakage, causes poor current flow and makes the copper strands brittle causing eventual breakage.
This seems to be accelerated by the proximity of salt water!  The only safe way to 'cure' it, is cable replacement.  You may also find that the battery pack is also defunct!
A good explanation of cause and effect is given here -
http://www.barbadosrc.org/misc/blackwire.php


The corrosion can and does travel some distance from the battery pack, so don't let it get to your receiver  <:( 
Cheers
Danny

Danny thanks for the link very informative, especially that the problem is related to NiCads, Take it then that NiMh are not effected in the same way or is that too simple an assumption.
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RAAArtyGunner

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Re: All Artisans of the Black Arts
« Reply #8 on: March 18, 2015, 12:13:06 AM »

 Thank you one and all.

Yes the pack is old and was being used after laying up for some time, by my grandson to power his recently restored Model boat.

The lead broke of and Son says Grandad can fix it?? so here I am.

Little bit out of my league but will replace wires and try the recharging and testing cells to see what happens.

Probably need to check any other Ni-Cad batteries and packs for Black wire disease.



 
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malcolmfrary

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Re: All Artisans of the Black Arts
« Reply #9 on: March 18, 2015, 07:19:30 PM »

Quote
Hi all, most if not all of the battery packs available come with a plastic shrink outer cover.  Whether this does not allow the 'leakage' to disperse I do not know.
Since the corrosion is caused by a mix of air, moisture + whatever is available and metal that said air can get to, all of the wire needs to be sealed against the air, especially the exposed bit by the solder tag.  While packs are shrink sleeved, examination shows that the end cap has a hole for the wires.  This is the path in for air, once it carries its bit of moisture with it, the moisture stays, and finds its way up the strands of wire by capillary action.  Thats why there is rarely any hope for an affected cable.  The plus-ish side is that it usually takes a few years to be troublesome with a large cable, so a new bit of wire might well outlast the cells.
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