Flashlight Care (maintenance):

A topic that frequently arises in my email box is the question of caring for a flashlight. What do I need to do? What should I not do? What products do I need?

Luckily, care for a flashlight is actually rather simple. Like any tool, a little bit of preventative maintenance will go a long way.

When you first get a light, it's a good idea to take it apart to the point normal for a flashlight and inspect it.

First, check for corrosion and dirt on the contacts. Heavy dirt can be removed from most contacts with a pencil eraser. Don't scrub, just rub. The eraser will do all the work. You should wind up with a fairly shiny metal contact for the batteries and bulb. Be sure to blow out the eraser dust left behind. If the contact is coated with a metal plating (some are gold plated copper) be careful with an eraser - it may take the plating completely off!

Caig Laboratories DeOxit is a great product to chemically clean and treat the contacts and will not harm the surface. The solution is 20% cleaner, 80% lubricant and contact preservative. Even contacts that don't appear corroded can usually benefit from a good wipedown with DeOxit cleaner. I found the best value to the the 59mm bottle 100% liquid solution (undiluted) based on cost/oz. and my amount of usage. I suspect most folks will find this bottle will last them a long time. Radio Shack carries a spray twin pack of DeOxit and ProGold, but the spray is only 5% DeOxit, 95% inert carrier/propellent, so you are getting a lot less for your money.

UPDATE: You can get small tubes of 100% DeOxit from FenixStore.com at a reasonable price. Click here for the DeOxit page.

If you don't need a cleaner per se, the 100% ProGold (now called DeOxit Gold) is 5% cleaner, 95% preservative/lubricant. This will help keep clean contacts clean. Again, get the liquid 100% product and avoid the sprays since they are only 5% product and 95% inert carrier. A thin layer is all that is needed.

Next, check the threads on the body tube. If they have grit or shavings on them, clean them off. This is especially important for metal flashlights as the shavings and grit will wear down the threads and make installation/removal of the threaded areas difficult. First; carefully remove any O-rings from the area where you will be working on the threads or you risk damaging the O-rings! If the threads are really filthy, scrub the threads of the body tube with an old soft toothbrush and some isoproply alcohol in a well ventilated area.

For the threads inside the head or tailcap, be careful; you don't want to flood the head or tail with alcohol. Hold them open side down and use a soft terry cloth, cotton balls, or Q-Tips either alone or dipped in the alcohol to clean the threads. Allow all parts to dry thoroughly.

Check your O-rings and seals. You should have carefully removed them before working on cleaning the threads. Clean the O-rings with a mild cleaner and damp cloth. Coat them with a thin layer of silicone grease. A good way to do this is to put a dab in a plastic bag with the O-rings and massage it around with your fingers to cover the O-rings with the silicone grease. This seems to work well and keeps the silicone grease off your hands. You don't have to buy the expensive stuff that the "connoisseurs" will tell you to get. Dielectric silicone grease from an automotive store is inexpensive and works well (the link shows the exact stuff I use all the time). Replace the O-rings carefully.

Lubricate the threads. On plastic lights I use the silicone grease, but on metal lights I prefer "Superlube" which is more of a liquid gel and contains teflon. You can get it at just about any hardware store in little precision application tubes, or from Radio Shack. Apply a thin layer.

If you are lubricating a dive light, Or a light that will be exposed to a lot of water, use a fairly thick layer of silicone grease on the threads and O-ring. Silicone grease is more resistant to washing away than Superlube and helps repel the water.

What is the difference between a thin layer and a thick layer of lubricant? A thin layer generally can't be differentiated from the surface it is sitting on. It coats the surface. A thick layer can easily be seen resting on top of the surface and will glob up a bit, but not excessively so.

Relubricate the threads and O-rings as described above at least once a year, or whenever they appear dry. Always wipe the threads and O-ring off with a dry soft cloth first before relubricating to get rid of any grit that may have accumulated. A full disassembly and cleaning is a good idea once a year if the light sees normal use.

For the lens and body, just use a mild cleaner and a damp cloth to clean it. Don't use harsh abrasives, especially on the lens. Polycarbonate lenses will scratch easily.

My Batteries Leaked! What do I do!:

If your batteries have leaked and damaged your light you have two options:

First, you can contact the battery manfacturer. The big name brands should all have guarantees that cover damaged products if the damage is caused by leaking cells. They may want you to send the product in to them for inspection, and if they determine that the batteries caused the damage you should get a check from them.

Second, if the damage isn't too bad you may want to fix it yourself. If there is still liquid electrolyte inside, dry it up and wipe out the light as best as you can with a damp cloth, then allow it to dry completely before proceeding. Clean all the contact areas carefully using the products mentioned above. You may have to use very fine sandpaper or those old ballpoint pen erasers (white, and tend to be abrasive) to scour the contacts a bit and make them shiny again if Deoxit doesn't cut it. When all the corrosion is gone, lubricate and protect your contacts with ProGold or Deoxit and your light should work again.

To prevent this from happening again, don't leave batteries in lights that are not commonly used, don't run a flashlight completely down and leave the cells in (this is the most common reason cells leak), and inspect your infrequently used lights at LEAST every 6 months and change out the cells as required.

Flashlight Feeding (batteries):

Batteries store energy and by their very nature can be dangerous. They contain hazardous chemicals and may explode or leak. When changing out the batteries, following these suggestions and safety precautions will help ensure that your light lasts a long time and doesn't suffer damage from either the energy stored in the cells, or from the chemicals that make them work.

• READ THE INSTRUCTIONS FIRST, NOT LAST.
• Use well known and proven brands of batteries.
• Always replace all batteries at the same time with new, unused batteries.
• Install batteries according to polarity (+ and -) diagrams.
• Do not use batteries that are not specifically recommended by the manufacturer.
• Do not mix new and used batteries.
• Do not mix brands (or types within brands) of batteries.
• Do not mix rechargeable and non-rechargeable batteries.
• Remove depleted batteries immediately.

That last one is something that a lot of people don't consider. When a battery is dead it is much more likely to leak and damage the inside of your light.

Other general safety precautions:

• Properly dispose of used batteries immediately.
• Do not attempt to recharge non-rechargeable batteries.
• Do not heat, burn, or puncture batteries.
• Do not dismantle batteries.
• Do not leave batteries accessable to children or irresponsible individuals.
• Follow all battery manufacturer recommendations and safety precautions.
• Follow all device manufacturer recommendations and safety precautions.
• Do not run with scissors.
• Do not cross the street without looking both ways.
• Do not play with matches.
• Do not jog though grizzly country while covered with barbecue sauce.
• Do not do anything that could be preceeded by the phrase "Hey! Y'all watch this!".

Sorry, I got a little carried away there...

Large battery manufacturers often have a guarantee that states that they will replace a device damaged by their batteries. If you have a battery leak and damage your light, contact the battery manufacturer and see what they will do for you.

Unlike what popular rumor states, you should never keep batteries in the refrigerator or freezer. When you take them out, condensation will form and cause corrosion. Store them in a cool, dry place.

Battery contacts can be cleaned with a pencil eraser if they get dirty.

In storage, alkaline batteries have a shelf life of 5-7 years, lithium batteries have a shelf life of around 10 years.

Here are some other articles I have written about batteries that you may find helpful:

Batteries explained (simply!)

Exploding 123A batteries???

Warning about using rechargeable 123A cells!

Pila 123A replacements and table of compatibility.

Low Self Discharge rechargeable AA/AAA NiMH cells!

Battery table of capacity and table of Li-Ion rechargeables (plus Q and A)

Useless Battery Trivia:

NiMH cells are Nickel Metal Hydride - most people know this. But did you know:

Alkaline cells are Alkaline Manganese Dioxide-Zinc
123A cells are Lithium Manganese Dioxide
L91, L92 cells are Lithium Iron Disulfide

What most people call "batteries", really aren't. A "battery" is a number of similar articles, items, or devices arranged, connected, or used together. The fact that there are a group of them working together is what defines a battery. This is why we call a group of artillery cannons working together, a "battery" of cannons.

To an engineer, AA, AAA, C, D, 123A "batteries" aren't "batteries". They're "cells". A 9V battery consists of a group of cells working together inside its case to make 9V, so it is a true "battery". Lantern batteries contain 4 F cells, so are also a true "battery". Car batteries also have several cells inside to produce and store electricity.

However, in common usage, "battery" and "cell" have become interchangeable and now mean the same thing when referencing a chemical power storage device that supplies an electric current.

123A Lithium cells are one 2/3 of an A cell. Hence 123A. (Yes there once was an A sized cell.)

Some 9V batteries contain six 1.5V AAAA cells, but each AAAA cell lacks the outer "can" so it is shorter than normal, and has the "nub" on the negative side of the cell instead of the positive side.

A 23A 12V cell (Used to power a Glo-Toob) actually contains 8 tiny 1.5V button cells in a stack surrounded by a wrapper.