Black Wire Corrosion ( has it gone away?)

[kc]

Years ago Black Wire corrosion seemed to happen a lot and crashed many models. Various theories were suggested for it occurring, some blamed the actual insulation colouring. Most people found it on the negative ( black insulation ) leads but I had a red lead just as bad. In every case the wire inside went crumbly and black and eventually fractured.

Nobody has mentioned it recently so has the gradual replacement of old radios with 2.4 Ghz just eliminated the old sets or has a cure been found by changing the chemistry of the insulation or the metalurgy of the wires?

[fly boy3]

Not 100% sure but I think it is down to the chemical make up of lipos. I think the BWS was mostly on nicads

[Peter Christy]

It was mostly caused by continuously trickle charging nicads. Most people put them on trickle charge (10hr rate) the night before they went flying. But if the pack had only had 3 or 4 flights previously, it was probably only 20-30% discharged.

Once the pack became full, the continued charging caused it to vent gas - which was slightly positively charged, and attracted to the negative terminal. This gas was very alkaline, and highly corrosive! The situation got even worse when the packs were charged in a damp environment, like a shed or garage.

Mostly, it went away when everyone started using peak-detect chargers. NiMhs never did seem as prone, though early ones did suffer from high self-discharge, which also reduced the possibility of overcharge between sessions.

--

Pete

[PeterF]

When I was first introduced to RC flying by my father in law he told me to put a small dehumidifier into my shed. I have no idea if that has helped things or not, but it did appear to be sound advise, it was one of my first purchases.

[kc]

Thanks for the comments. Peter Christy's explanation seems very plausible. However I wonder if the standard Tx & Rx 'wall wart' chargers that the majority seem to use are actually peak detect?

Let's hope black wire corrosion has gone away for good - but be on the lookout for it anyway.

[Tim Cheal]

I think I have rediscovered it.

I lost control of my Acrowot today which hit the ground in a near vertical dive. Luckily I wa snot too high and the engine mount has broken. The damage is limited to the engine mount and the cowl (which was pretty tatty anyway!). On investigation back home I found the Spektrum AR6210 orange light would not stay on and the servos were erratic (much like it had been in the air). Spookily, with a new battery pack everything worked fine again, so I reconnected the previous battery pack. Although the voltage read good at 5.67v (96%) the receiver would not work properly when connected to this battery pack, but always worked fine with others. I checked all the connections and sure enough found the black wire corroded at the plug from the battery to the switch harness. I keep my models in the garage and tend to keep them on "trickle" charge with a Ripmax charger, so presumably I hit all the high risk areas for black wire corrosion.

If my diagnosis is correct then sadly it hasn't gone away!

To be honest I was a little relieved to solve the p[problem, as there is nothing worse in my opinion than not finding the problem, All works fine again after cleaning the connection off, but a new battery pack is on its way anyway (and a new Carbon Copies cowl)!

Tim

[gangster]

When I was first introduced to RC flying by my father in law he told me to put a small dehumidifier into my shed.

Peter this could be wise advise. I believe that it is made worse by keeping the models in a damp cold place. I always remove the receiver batterys and keep them indoors in the warm together with the TX.

Not had much problem doing that

Black wire corrosion can creap up the wires and affect the switch and beyond, I am sure the demise of many a model has been due to the switch going intermittent. The clue to look for is green/black on the pins of your battery plugs.

Not sure its just nicads either. I once repaired a transmitter that used dry cells the negative lead was trashed both sides of the switch and the switch had to be changed as well.