flickering flashlights

[demogo]

Hi,

Quick question from a newbie.

I have a couple of problem flashlights and would love to hear some feedback from everyone.

1) 3 LED pen light using 3 AA batteries and the LEDs flicker at times -- sometimes the LEDs are at half brightness, sometimes they almost go out or they do go out entirely. Shaking the flashlight a bit or changing the pressure on the cap that puts pressure on the batteries will usually fix the problem temporarily.

What's likely going on with this light? Changing the batteries doesn't seem to make a difference.

2) Reading light - incandescent bulb and a variety of AA batteries ranging from alkaline to 2700mah powerex NiMh. The light is mostly at a steady level but it occassionally will dim and then eventually brighten back up.

Again, what's going on here?

I suspect possible oxidation of the contact points on either the batteries or flashlight contacts. Am I off-base? If it is oxidation what do I do about it?

Thanks!

 

[hank]

Radio Shack will have electronics cleaner; plain alcohol will do.
Look for corrosion between the bulb and case, that has to be an electrical path, just like between batteries and center of the bulb, and batteries and spring, and spring and tailswitch if there is one, and inside the switch area.

You can get conductive cleaner (used on antistatic mats among other things) or conductive nyogel lubricant grease.

 

[hopkins]

try stretching the spring out so it pushes on the batteries harder demogo.

If you're too lazy, like me, to get up and find some rubbing alcohol
and paper towels to clean the battery ends try this: rub the battery
ends on the carpet, or your pants, etc. to polish them and remove any
dirt.
---minimum effort for maximum result - Ben Franklin

 

[demogo]

Thanks Hank and Hopkins.

I stretched out the spring and presto, the LED penlight no longer flickers.

Hopefully it will stay that way.

The other light will be more challenging because it's an odd reading light with a flexible neck that acts as a switch when it's extended -- and it uses a weird bulb. Not much I can do with it other than clean the contacts in the battery compartment with alcohol and clean the batteries top and bottom.

Thanks for the help!

 

[Derek Dean]

Well, as far as your odd reading lamp goes, I hope you aren't mixing an assortment of alkaline and NiMh batteries, a definite no-no.

Clean the contacts in the battery compartment and then install new batteries, either all alkaline (the same brand) or all fully charged NiMh cells. Also, clean the contacts where the bulb installs. That might help.

 

[demogo]

Well, as far as your odd reading lamp goes, I hope you aren't mixing an assortment of alkaline and NiMh batteries, a definite no-no.

Clean the contacts in the battery compartment and then install new batteries, either all alkaline (the same brand) or all fully charged NiMh cells. Also, clean the contacts where the bulb installs. That might help.

Nope, same battery types. I've run NiMh cells in it for many years and it's worked amazingly well.

What's odd about the reading light is the "neck" assembly. Mine isn't an LED (it's 10+ years old), but looks like this:

http://www.lumatec.com/reading/ev_150.htm

I'll give those contacts a good cleaning with alcohol and see how things turn out.

Thanks!

 

[hank]

Oh, I've still got most of the bits of one of those reading lights -- there are two flexible metal strips on that bendy pullout thing, and the electrical contacts slide along them as the thing's pulled out. So the whole length of it can get dirty, but the very bottom, hidden inside the case at full extension, is where the gunk accumulates.

There's another post recently about another flickering light where several people recommended the Radio Shack electrically conductive 'bulb lubricant' (the stuff you put on threads so you don't shatter an incandescent when you go to remove the burned out bulb, to keep it from sticking in the socket; also used for automobile bulbs a lot). That might be good. Or there are lots of more pricey options for cleaning electrical conductors.

 

[demogo]

Thanks, Hank.

I'll check it out.

 

[chmsam]

DeOxit Gold removes the oxidation and tends to keep it coming back. I use it on the contacts in the flashlight, on the lamp assembly, and on all battery contacts. Works well. Get out an old and heavily oxidized flashlight, hit it with DeOxit Gold and you'll think you put in new batteries.

Cheap fixes also include a clean pencil eraser to rub off the oxidation or an emery board (kind of a softer version of a nail file) for the same thing. Oxidation will come back with these however. Alcohol will also remove oxidation but not keep it from coming back.

 

[demogo]

Hmmm. That sounds like some good stuff.

First I guess I need to try the alcohol and make that fixes the issue temporarily.

Where would I pick some DeOxit Gold at a reasonable price?

 

[chmsam]

Caig is the manufacturer. It is available on-line and at electronics repair/parts stores. Radio Shack sells it, too.