black wire

[Ernie]

Hi guys,

How do you check the leads for the dreaded black wire? If I scrape off a wee hole to have a look, I can't use heat shrink  to repair the hole, because it won't slide over the plugs. Maybe I just use insulating tape, but it's not very neat.. Any clever ideas?

ernie

[260 Flyer]

Ernie

Just warm the insulation by the solder joint on the cell and you should be able to push it back up the wire a quarter of an inch or so which should be enough to see the bare (solder free) copper.

I thought the dreaded Black Wire went out with Ni Cads, or maybe you're still using them.

Rob

[Tim Mackey]

I dont know if you have seen this or not, but the guy I get all my leads and plugs etc from sells a rather neat twisted servo / battery cable with a clear insulation covering on the black / negative lead. Heres a link.

[Malc. Nicklin]

 “Black Wire Syndrome” is terminal not just to the battery pack but it as the ability to travel along the Negative wire through the on/off switch and continue through to the printed circuit board in the equipment itself.

I’ll not going into details about the (electrolyte gas creep age) and the technical crap but it can be caused by leaving the gear in an uncharged state for long periods and don’t forget Ni Cads self discharge over a period of months. When this happens the cells go down to zero volts and allow the electrolyte to escape from inside the cell and mix with air and if it’s damp were they are stored the electrolyte and moisture turn into potassium carbonate and the problems start.

It can also be started by the batteries getting to hot or have been soft solded and the heat as warmed up the cell to much. 

 What to do to save our valuable equipment from the dreaded Black Wire Syndrome, if you are thinking of storing the gear for any length of time remove the batteries from both the model and the transmitter and check to see if there is any white powder or the leads are starting to get brittle change the packs at once and also check the wiring harness in the model to see if this is going brittle and change that also.

Don't try and save it get rid of the cable before the Black Wire Syndrome Cancer gets into the equiment. 

This can be a saftey issue so please check it out  

Happy Landings  Malc. Nicklin VH 56289

[260 Flyer]

Malc

Has BWS been noted on anything other than Ni Cads?

Rob

[Tim Mackey]

I beleive it is the chemistry of nicd that creates it, so generally speaking it is unlikely to occur with Nimh or lithium....

[260 Flyer]

Thanks Timbo

That's what I thought, just the way the subject re-surfaced out of the blue made me tw-tw tw-tw-tw tw-tw-tw-twitchy!

[Tim Mackey]

....

[iawnski]

glad ive gone all nimh  ican relax now  no bws(dont bws spell bus in english) sorry going off on one i will change honest

[Former Member]

[This posting has been removed]

[iawnski]

 i lke it eric

[Roy Hill]

Hi guys,sorry to bring it up but being a retired motor engineer i can remember the days when vehicles had side and flasher lamp connections exposed to all sorts of weather, although they were covered by a rubber boot, the earth wire used to suffer from bws, also trailer sockets were particularly vulnerable.It was usually only the ground wire that was affected.imo the common denominator seems to be moisture,so  whatever the type of cells,keep them dry and check regularly,and don,t put your tranny on the grass, use a mat! regards,roy. ps. does anyone know the chemical composition of the corroded copper /green verdigris(bws)? pps.just a thought, on the vehicles bws happened on both pos and neg earth types     sorry for this,iawnski, don,t panic,roy. gotta go ,verbal diarrohia attack etc

[Tim Mackey]

As far as I know...( and I am no expert ) it is caused by the potassium hydroxide paste ( which is the basis of the cell's electrolyte ) mixed with carbon dioxide present in the air which then becomes potassium carbonate. The humidity of damp, or simply generally humid places then causes this white powdery stuff ( sometimes called "salting" ) to almost return to a liquid which can then creep back along the wire. In all cases it requires that some of the cells electrolyte has leaked out - albeit in very small doses - possibly through either overheating, cell inbalance causing one cell to get "driven" by the others, or simply a leaky vent.

As the electron flow is out from the battery along the negative wire and back in via the positive wire it results in a wicking action out along the negative lead and is why it affects the negative lead more than the positive.

I imagine the strong sulphuric acid based electroyte in older car batteries would have a similar corrosive effect.

[Chris Dowsett]

Standard "O" level chemistry reaction.  Acid + Base = Salt + Water.  If any one wants to do further research try http://en.wikipedia.org/wiki/Acid-base_reaction_theories  Timbo's KOH paste is a very strong 'base' which would explain why NiCad's are worse than NiMh.

Modern TX's and RX's in plastic enclosures help reduce condensation.   Use crimped, welded, or gold plated connections.  Always connect batteries via a gold plated plug and socket (especially the TX).

[Malc. Nicklin]

Hi chaps, well I started something and nice that people have taken note of the problem.

 NiMH use the same sort of electrolyte (potassium hydroxide) and the construction of both cells are basically the same so you can expect to have simular results with NiMH cell but I have not personally seen it.

Some times there is a residue of electrolyte left over from the manufacturing process which can start the ball rolling, soldering directly on to the nipples of the cells instead of tags will get it started very quickly as these cells don't like getting localized heating.

There is a good artical on this site re using Li Po's in the TX which I think is one of the best ideas yet.

I beleive in the future all our gear will be supplied with Li Po cell technology so the problem will go away.

 Happy Landing Chaps .

 Malc...