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!
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
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
• 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
Pila 123A replacements and table
Low Self Discharge rechargeable AA/AAA
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"
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.