rust removal solution?

[monster]

i just had an intermittent fault on my bike and i tracked it down to the hall signal connector. it must be rusted or something because i just pluged and unpluged it a few times and it worked again. i use 6 pin PS2 (kbd/mouse) connectors as my hall connectors. is there an anti-rust solution that i could just dip the plug in that will clean the contacts? i think i read about it on here. was it white vinagar?

 

[joeworrall]

Phosphoric acid is the main ingredient in most rust removers, you want to get something that is based on this and it should clear the rust right up, be sure it is rust thats causing the problem first and not just a loose wire that is shorting out and tripping the BMS (happened to me a couple of times with the hall sensors). Each time connections spark a layer of carbon builds up and the connectors will become slightly disfigured.
White vinegar does contain Phosphoric Acid but it will not be as effective as buying a proper rust remover.
If everything fails, just buy some new hall connectors.
Joe.

 

[AussieJester]

Ranex Rust Converter is the best rust converter i have ever used, oxidises the rust.

Good to have a bottle in the workshop for times like this

KiM

 

[CowtownPeddler]

Coincidentally, Coca-Cola is like 80+% phosphoric acid....

 

[Grinhill]

I guess if you're talking about a connector problem, the corrosion will probably not be real "rust" (corrosion on iron or steel). So these solutions may not be appropriate for connectors coated in tin, nickel, brass, or whatever.

Our ebikes are probably a mixture of a dozen different metals, so there's a lot of electrolytic action caused by the dissimilar metals.

You can usually just use some sort of soft scouring pad to clean off surface corrosion, or there is stuff in an aerosol can called "electronic cleaning solvent" which may help.

 

[monster]

my solution was to take out the plugs and just solder the motor-controller hall connection. is this what others have done?

 

[pwrbkr31]

For non soldered and sealed connections, once the bullet, spade etc connections are good, tight and clean they should be smothered in a dielectric grease during assembly to keep further moisture out. Then the fitting should be encased in shrink fit plastic sheathing. Some heat shrink tubing comes internally pre glued which melts and adheres during the shrink process and further seals the ends where the wires emerge. If you have heat shrink tubing without the internal glue and you want to seal it or use the heat shrink as a physical hold together to stop the connection coming loose, glue gun sticks melt easily on the end of a soldering iron, don't make a mess of the iron either, very easy to wipe off the iron tip, almost zero smell, smear it on the wires insulation before the shrink tube goes over and it will heat up and stick during the shrink process. Glue gun sticks also soften enough under a hot air gun to be wiped onto the wires before the shrink goes over.

The same process works really really well all over soldered joints you never want to see or touch again.

back to dielectric grease...
I have industrial equipment that survives heavy duty pressure washing without letting ANY moisture into the wiring connectors. There are three computers on that machine that are a nightmare to trouble shoot when wires go bad, hence the dielectric grease inside every quick disconnect multi (up to 24 pin) connector. I can pull a plug apart that hasn't seen daylight for years and the dielectric is still there doing its job of not allowing corrosion to start.

I use the dielectric grease from a truck supplies. Auto parts stores have smaller tubes at higher prices.

Alan

 

[gogo]

+1 for dielectric grease used on connectors known to corrode.

This stuff doesn't physically exclude moisture from spaces within a connection like grease, but it does a good job preventing surface corrosion:

http://www.aircraftspruce.com/catalog/cspages/acf50.php

 

[ebent]

http://www.ospho.com/ will remove rust. after that you need to do something quick. It needs to be protected because it is bare metal. I have never used it with electronics.

ebent

 

[dnmun]

copper is not steel and does not rust. do not use phosphoric acid. the pins make bad connection because they get loose and don't fit tight enuff to carry the current. solder them.

 

[LockH]

"Electrolytic Rust Removal" on site instructables:
http://www.instructables.com/id/Electrolytic-Rust-Removal-aka-Magic/

 

[xenodius]

I hope you're just joking about the Coke and white vinegar. Both are pretty acidic, but Coke is not 80% phosphoric acid (I believe it is unstable at standard atmosphere and pressure at that concentration, and would in fact explode spontaneously and violently, as it would be a superacid) and white vinegar is acetic acid, not phosphoric acid. Any acid will do the trick though, you just need a hydrogen donor.

I personally like Naval Jelly. That said, preemptive use of dielectric grease is a must for halls. =)

 

[teklektik]

i just had an intermittent fault on my bike and i tracked it down to the hall signal connector.
it must be rusted or something because i just pluged and unpluged it a few times and it worked again.
i use 6 pin PS2 (kbd/mouse) connectors as my hall connectors.

Your connectors do not have 'rust' they are suffering from 'fretting corrosion'.

Before you can address the connection issue you need to understand what's going on here...

• How your connectors work:
  The connector pins are some alloy chosen for it's dimensional stability/springiness so the male pins don't bend and the female sleeves will continue to apply cortact force with age and use. The connectors are plated with tin to give corrosion resistance. When tin oxidizes, the oxidized layer of molecules prevent the air/moisture from contacting the underlying layer and the surface becomes passivated - it oxides no further. So - the dull gray color of the oxidized tin coating is intended by design.
  
  When you slide the contacts together, the contact pressure displaces the coating, you get tin-to-tin contact, juice flows, and all is well.
  
  
• What goes wrong:
  As the connector pins wiggle around microscopically (we're talking human hair width jiggling), the nearby oxide gets plowed up and collects as detritus near the (new) contact point. Any newly exposed tin oxidizes straightaway. As time goes by, a microscopic pile of insulating tin oxide builds up and works between the contact points. However, being just a pile of micro-rubble, the connection tends to fail in an intermittent fashion and often is characterized not as a broken connection but rather as high/varying resistance as the rubble pile moves around (intermittent). This is exactly your symptom.

How to fix this:

• The Temporary Quick Fix:
  Simple disconncet/reconnect the connector a few times. The normal wiping action of the pins will plow through the debris and reestablish a connection. You can often see the corrosion as a dark gray or black smudge on the male contacts. You did this already, and saw that it worked.
  
  
• The Better Fix:
  Douse the connector with 'Electronic Contact Cleaner' (Radio Shack, Amazon, etc. - e.g. 'CRC 05101 QD Electronic Cleaner'). Make/break the connection a bunch of times. The solvents and liquid will float and wash away the debris from the surface. You want to do this to start with a clean surface with no leftover contamination. There is no reaction with the tin oxide - this is a non-reactive cleaning solution that simply flushes away stuff and dries without (insulating) residue. It's safe for plastics. In a pinch, use an old toothbrush and isopropyl alcohol.
  
  Not surprisingly, when you are done the contacts will not be 'bright and shiny' - they will be the desired gray color since the protective oxide layer will remain intact - just the poo will be gone.
  
  Wipe the connector with a thin film of Permatex Dielectric Grease (Auto parts stores, Amazon) and reassemble the connector. No need to slobber it on. (Dielectric grease is primarily silicone grease and is inert making it insoluble (won't wash away easily) and safe for any plastic, but petroleum-based Vaseline is a workable second choice.) When the connector is re-assembled, the contacts will plow through the grease and work normally, but the contact point will have a tiny barrier of grease around it. This discourages fretting corrosion because the air/moisture cannot attack newly exposed tin as the contacts wiggle - with no new oxide, the pile of insulating material does not build up (or does so very much more slowly), so the pins stay in contact and signals continue to flow.
  
  
• The Best Fix:
  Use a proper connector.
  
  Connectors subject to vibration typically have some mechanical means to hold the outer shrouds rigidly together to minimize/eliminate movement of the pins. The pins themselves are often 'floating' - they are loosely held in the should so even if the shroud wiggles, the pins don't. And, of course, the pins themselves are designed for high contact force and have thicker plating. Gold plating is inert (cannot oxidize) and so is immune to fretting corrosion and presents the best step up in reliability.
  
  Unfortunately, you chose to use common PS-2 mouse/keyboard connectors. There are only rated for a limited number of insertions (poor contact pressure, thin plating), have a non-rigid shroud, and have short non-floating pins. In short, they are cheap electronic connectors that were never designed to withstand the vibration of on-road use. You can mitigate the problems with the procedures above, but basically your connector choice seems sub-optimal for this application.
  
  In this case, where the wiggly PS-2 shroud is a contributing failure component, you might wrap the joined connectors with self-fusing silicone tape (Tomy Tape, or 'Stretch and Seal' in the plumbing dept of Home Depot or similar stores). This only sticks to itself and will maintain tension on the junction. Unlike heat shrink, this is easily removed with a quick nick of a utility knife (or just fingernails in the field).

In any case, it should be clear that under no circumstances should you 'clean' the contacts with anything abrasive or acidic. This simply removes the all important plating. Things may work swimmingly for awhile, but once the protective plating is gone, you are doomed to continued future cleaning as regular maintenance, since you will have re-designed the connector to lack the original oxidation prevention mechanism.

Hope this helps....