Flashlight acting crazy! What to clean contacts with?

Hello all

I won a crelant 7g1 last year, it has actually been a pretty good light and has withstood many gigging trips where it has been dunked in salt water. I think if I can clean the threads or contacts, or something. I can get it working correctly again. It's like it is not making a good connection with the battery. I run it on lithium ion rechargeable. It will not scroll through the brightness levels right. And it flickers on and off sometimes. What should I do to it? What chemical should I use?

Isopropyl (rubbing) alcohol works best. Use an old toothbrush to get into the threads, and use a Q-tip to get into harder-to-reach areas like the tail cap.

Use Deoxit and ProGold. They are pricy but they pay for themselves. In my experience mine not only paid for itself very quickly, but over and over again. Great for cell phones.

While Isopropyl alcohol has has some utility in cleaning contacts, avoid the 70% solutions and if alcohol must be used, use the 91% mix.

Deoxit/Progold from Craig laboratories are very good, i use them in my Hifi/DIY audio hobby. It just strips/cleans the threads and gives you clean, bare, shiny aluminum. If that is too costly, then any spray-type contact cleaner for electronics is good enough also. isopropanol is ok, i have that 99.8% pure for electronics type, but not as good as contact cleaner for cleaning oxidised threads. Aluminum will always oxidise, be it an expensive Surefire or a 5 dollar budget light.

The first part of the sticky thread on lubes has some info on cleaning and maintaining lights so check that out.

The choice of cleaning products and whatnot should depend on what you are trying to clean up or dry up since some products work better for certain situations and other products not so much.

If it's just gunk from being dropped in the mud and the muck then a few cotton swabs and a drop or two of dish washing soap (NOT dishwasher soap) in water can do a great job on threads and the outside of the light. When done wipe down the threads and the light well using a damp cotton cloth. I use shop cloths that are used for nothing else but cleaning my lights but an old t-shirt or terrycloth washcloth will do the trick. Just use a cotton one and be sure that it's good and clean.

I use a good electrical contact cleaner (like DeOxit) on the tailcap and LED module contacts. I'd also do the same for the battery contacts but check the battery on a battery tester first. A dead or dying battery can make a light do strange things. By the way, just measuring the voltage will not tell you enough about the battery so use a tester. Also it's important to wait at least five minutes before putting everything back together so the cleaning fluid and DeOxit Gold can dry completely.

Doing this solves a lot but not all problems. Hopefully you'll be good to go.

If you're going to be taking a light into a damp/wet and/or dirty environment be sure that the o-rings are in good shape and that you've lubed the rings and the threads lightly and that you are using the right lube or grease.

A clean pencil eraser is probably the least aggressive of the mechanical means available to clean contacts.

There is also some kind of conductive contact goop that auto dealerships use to smooth over the contact surface asperities, thus increasing contact surface area, thus decreasing contact resistance.
It may be a cheap, temporary fix, though. That's probably why dealerships use it.

If you measure the current through and the voltage drop across these contacts we will have a benchmark for what bad contacts measure in terms of contact resistance.
Possibly more than 100 mV at rated current means bad contacts, but this number is for relays. BTW, I have some confirmation of this value when I replaced a flaky HVAC blower motor relay. The new relay read way less than 100 mV.

xul said:

A clean pencil eraser is probably the least aggressive of the mechanical means available to clean contacts...

Click to expand...

A clean pencil eraser is pretty aggressive for cleaning plated contacts.

What would be the best stuff to use if you're trying to clean off corrosion or whatever it is that forms after they have an unfortunate encounter with a leaking battery?

This has happened to me a couple times, and both times I cleaned it as best I could with a pencil eraser, then I put a drop of oil on the contact and then used the pencil eraser again. It seemed to allow the device to work again, but the contact still doesn't look as good as it could, so I'm thinking there must be something better.

Baking Soda for carbon zinc & Vinegar for Alkaline battery leakage. You might have to let it soak for an hour or two if its bad & redo it a few more times until clean.

+

DeoxIT should be an absolute prerequisite for everyone in CPF.
your stuff will run significantly better & its a must have for tricky troubleshooting

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DeoxIT® D-Series D100L Squeeze Tube, 100% solution, 2 ml,

I have DeoxIT in a "spray" tube (along w/DeoxIT Gold) which I got at Radio Shack. I guess that's ok for the tailcap & bezel contacts, but am assuming the "gel" version is best for the threads. What I've mostly used for threads is a tube of silicon "grease". Would the general DeoxIT be better than that

Is DeoxIT/DeoxIT Gold good for use on threads? Should grease still be applied? I don't think Super Lube is conductive.

DeOxit and DeOxit Gold are not lubes. They are an electrical contact cleaner/deoxidizer and an oxidization preventer/clean contact preservative (respectively). So yes, there are other products to use for cleaning and lubing threads and o-rings. Read through the sticky thread "Comprehensive Grease and Lube Thread" at the top of this section for more basic info. Since there are a lot of choices for lubes and a fair amount of discussion that has gone on for quite a while read through the info.

Basically it depends on what material the o-rings are made from and you can often get that info from the manufacturer.

Makes sense, so grease won't affect the protection from DeoxIT? Although putting grease back on will make the contacts "dirty" again...

The grease pretty much goes on the threads and o-rings only and sparingly. You then wipe up any excess with a clean, dry cloth.

The DeOxit and DeOxit Gold or any other electrical contact cleaner is dabbed or sprayed on lightly and only on electrical parts. You then allow it to dry thoroughly.

You probably do not need to use DeOxit on threads to insure contact since there is a large enough contact area.

For heavily corroded contacts I have had good luck with with a Excelta scratch brush (nylon or fiberglass - don't use steel or brass as they are way too aggressive) or a light grit sand paper held by long neck pair of forceps.

I use a cloth and a stiff toothbrush for the threads, and a clean eraser to gently clean the contacts.

If the corrosion worked its way into the actual switches, all the contact cleaning in the world won't help. You'll need to replace the switch. At best you can try to take the switch apart and manually clean the insides. I've done that to several lights of mine that flickered and had clean contacts. Sometimes a buildup will form on the switch contacts.

Might not be a problem with corrosion or oxidation. Might be a problem with the light engine being loose in the head. See if you can tighten the light engine (screw it in further). If you can, it was flickering due to loss of ground to the light body.