Today�s digital cameras aren’t like the venerable Leica that is fully
mechanical. They depend on battery power to operate and the camera’s LCD
monitor and flash can drain your batteries very quickly. If you use the
wrong batteries or don�t conserve power you can easily run out of battery
power after only a few pictures. In this section we look at the specific
issue of digital camera batteries.
Every year over 15 billion batteries are produced and sold
worldwide. Many are alkaline batteries which are discarded after a single
use. There is an old ad line in a TV commercial for an auto maintenance
service that goes “You can pay me now or you can pay me later.” The same
line can be used when discussing batteries. Because alkaline batteries are
so cheap, many people buy them for their camera only to discover that they
are consumed at a shockingly fast rate. To keep battery costs low in the
long run, you have to spend more up front for rechargeable batteries and a
battery charger. When you take the plunge, don’t be enticed by
rechargeable alkaline batteries. These are good for some uses but they are
not a good alternative for use in digital cameras. They typically have an
even lower capacity than standard alkaline batteries. This means that if a
standard alkaline only lasts for a few exposures, a rechargeable alkaline
will last for even fewer!
Despite alkaline batteries being a poor choice for economic
reasons, they will work in many digital cameras. In fact, if you have run
all of your rechargeable batteries down, they are the battery of last
resort. When desperate you can find them in almost any store anywhere on
the planet.
Choosing rechargeable
batteries
Thanks to recent advances in both batteries and battery chargers there
are now alternatives to alkaline batteries. In fact, most digital camera
manufacturers recommend higher capacity and more economical rechargeable
nickel-metal hydride (NiMH) or lithium-ion (Li-ion) batteries. When
replacing batteries for a camera you own, read the manual that came with
the camera to be sure you select the correct type.
NiMH (Nickel-Metal Hydride) batteries are the
most popular digital camera batteries. Search long and hard, talk to
everyone who knows anything, read as much as you can, and the answer is
always the same; Nickel-Metal Hydride batteries are what you want. They
are rechargeable, environmentally friendly (made from non-toxic
materials), and relatively inexpensive. More importantly perhaps, they are
designed for high-drain applications such as digital cameras and give you
more pictures per charge than any other standard battery type other than
the much more expensive lithium ion batteries. If they have any weakness,
it’s their overall life; lasting only about 400 charge and discharge
cycles.
NiCad (Nickel Cadmium) batteries were
traditionally the most widely used type of rechargeable battery overall
but are rarely used in digital cameras. However, they are made from highly
toxic cadmium and create an environmental nightmare. They charge quickly,
last approximately 700 charge and discharge cycles, and perform well in
low temperatures.
It’s widely believed that if you don’t fully discharge a NiCad
battery before you recharge it, it will develop a memory effect.
Over time, the stored charge gets smaller and smaller and the
battery fails more quickly when used. For instance, if you
repeatedly recharge a 2 hour NiCad battery after using it for 30
minutes, it will develop a memory that limits the battery’s run
time. The only way to avoid this phenomena is to fully discharge a
battery before you recharge it. NiMH and LiOn batteries don’t have
this problem to any noticeable extent.
So do NiCad batteries really have a memory
effect? Answering this question is a sure way to start a
flame war on the internet so the simple answer is yes and no. NiCad
batteries do suffer from a voltage depletion phenomenon that is much
like what people call the memory effect and which can be reversed by
conditioning
the batteries. The more common damage to NiCad batteries, which
is irreversible, is caused by poorly designed chargers that continue
to deliver current to the batteries even after they are fully
charged. “5- hour” and “8-hour” chargers can easily damage NiCad or
NiMH batteries.
Do NiMH batteries have memory
effect? NiMH batteries can
experience voltage depletion similar to that of NiCad batteries.
However the effect is much less noticeable. To completely eliminate
the possibility of NiMH batteries suffering any voltage depletion
effect some manufacturers recommend an OCCASIONAL deep discharge of
NiMH batteries followed by a full recharge. However, this isn’t
something digital photographers have to worry
about.
LiIon (Lithium Ion) batteries last twice as long
as NiMH batteries of equal size and don’t lose their charge as quickly
while in storage. The problem is that since they are newer than other
battery types, they are not yet available in as wide a range of models and
are more complex to manufacture and therefore expensive. They can be
charged and discharged as many times as NiMH batteries but normally become
unusable after 2-3 years.
Which are better, NiCad batteries or
NiMH batteries?
For electronic devices it is better to use NiMH batteries
than NiCad batteries. NiCad batteries use Cadmium, a highly toxic heavy
metal, that can damage the environment if not disposed of properly. (They
should be recycled; not discarded). NiMH batteries usually have a higher
capacity than NiCad batteries of the same size. Some people argue that
NiCad batteries deliver faster discharge rates than NiMH batteries. While
this may be true under certain circumstances, the difference is not
relevant when considering power sources for electronic devices such as
digital cameras or portable music players. (If you are choosing a battery
to drive a high torque power screwdriver, then NiCads can outperform
NiMH). NiMH batteries require more sophisticated chargers than those
typically used for NiCad batteries but smart chargers designed especially
for NiMH batteries are now readily available.
What about Lithium and Lithium Ion (LiIon)
Batteries?
Lithium and LiIon are batteries are used in some digital cameras.
Although both use the element lithium, they are functionally quite
different. Lithium ion batteries are rechargeable, lithium batteries are
not.
Lithium batteries come in standard sizes and voltages, deliver two to
three times as many shots as alkaline batteries of the same size, and have
a shelf life of up to ten years. However, they are much more expensive
than alkaline batteries. While they may be too expensive for everyday use,
their excellent shelf life and high capacity make lithium batteries ideal
as spare batteries. Lithium batteries are well worth their high price if
they mean you will be still able to get a great shot after your
rechargeable batteries have run down.
Rechargeable lithium ion batteries are used in some digital cameras,
especially those made by Canon. The good news about LiIon batteries is
that they have an excellent shelf life and have a higher storage capacity
than NiMH batteries of the same size and weight. They also have a
predictable voltage curve which allows cameras to have a reliable “fuel
gauge” indicating how much charge is remaining.
The bad news about LiIon batteries is that they are not available in
standard sizes such as AA and are much more difficult (expensive) to
manufacture. This means that, unlike NiMH batteries, you won’t have much
choice when it comes to buying extra batteries or faster battery chargers.
Be prepared to pay as much as $50 for a LiIon battery and even more for a
charger. (If any one is aware of third party LiIon batteries or battery
chargers please let us know, we will be happy to pass that information
along.)
Batteries are rated by voltage and milliamp hours (mAH). Most AA-sized
NiMH batteries are rated between 1200 and 1600 mAH. A 1600 mAH battery can
deliver 1,600 milliamps (mA) for one hour (H). Generally speaking, the
higher the rating, the more pictures you can take (all other factors being
identical). How many you actually get depends on how energy efficient you
are because the camera consumes energy between shots as well as when
shooting. If you’re careful, you might get about 100 shots per charge.
However, if you use alkaline batteries, do lots of zooming and focusing,
or leave the monitor on all the time, you might get only 25 or so.
Choosing a battery charger
There are so many battery chargers on the market it can be hard to
choose among them. Just keep in
mind that many features add to the cost of a charger. They range in price
from about $8 for stripped-down models to $50 for fully-loaded models.
Generally, the faster and more flexible a charger is, the more expensive
it will be.
NiMH
and/or NiCad? Most NiMH battery chargers can also handle NiCad
cells. But the reverse is not always true. If you want to charge both
types of batteries make sure the charger you get is designed for both.
Don�t use a NiCad charger to charge NiMH batteries. It won�t necessarily
damage them, but it won�t fully charge them either.
Many of the inexpensive NiMH battery chargers are simply
NiCad chargers that have been modified slightly. Typically a 5 hour NiCad
charger has a switch that allows the charge time to be increased from five
hours to eight hours making it into an 8 hour NiMH charger. You might have
to be careful when using this type of charger. While it is less expensive
to manufacture than a smart charger, it can lead to overcharging and
battery damage.
Size
of cells? Most digital cameras use AA size battery cells.
However more and more cameras are starting to use proprietary battery
sizes. If your camera uses something other than AA or AAA batteries you�ll
need to buy a special charger designed specifically for your camera�s
battery and your choices will be very limited and probably very expensive.
As far as we know, if your camera uses LiIon batteries, you will need to
use the batteries and battery charger provided by the manufacturer.
Number of cells? Since it�s important to keep
your batteries together in sets, you will want to choose a charger that
can charge the same number of cells that your camera uses. Almost every AA
battery charger can charge four cells at once. But if your camera uses
only two or three cells, you should get a charger that also charges just
two or three cells at a time. Even if your camera uses four cells at a
time, you may decide to start using rechargeable batteries in your FRS
radio or MP3 player. In that case, the ability to charge two or three
cells might be useful.
Charge time? How quickly a charger charges a set
of batteries is probably the most important issue to most people. The
speed of a charger also has the biggest impact on the price of the
charger. Ignore labels such as “rapid charger” or “overnight charger” and
find out how long it really takes a particular charger to charge a set of
high capacity NiMH batteries. The fastest chargers on the market (as of
2/2001) can charge 1600 mAh cells in a little over two hours. These
chargers have a charge rate of about 800 mA.
It’s pretty easy to estimate how long it will take a charger to charge
your batteries. Simply divide the capacity of the battery by the charge
rate of the charger, then increase the amount of time by about 20% to
allow for a certain amount of inefficiency. As an example, a battery with
a capacity of 1200 mAh will require about 6 hours to be fully charged by a
charger with a charge rate of 250 mA. (1200 mAh/250 mA x120%).
Incidentally this example is pretty typical for a standard AA NiMH battery
and a typical “rapid charger.” Keep in mind that a battery that is only
partially discharged will be recharged in less time.
Some people wonder if rapid charging reduces the life of
their batteries. It can, but it won’t if the batteries and charger are
designed for quick charging. With the right smart
charger, most NiMH batteries can be recharged in as little as an hour
without any damage or reduction in their life.
Do you mind AC adapters and
cords? Battery chargers normally get power from an AC
outlet. Some chargers plug directly into AC outlets. These plug in
chargers have built-in AC to DC converters which provide the DC power
necessary to charge the batteries. A plug in charger normally makes for
the neatest solution. If you decide to buy a plug in charger, you may also
want to look for one with a plug that folds into the charger when it�s not
in use.
Many chargers require an external AC adapter known as a “power brick,”
that plugs into an AC outlet and connects to the charger with a thin power
cord. Since the brick and cord adds to the clutter of your home or office,
it�s something to consider. In addition to being unsightly, the power
brick and cord can be a nuisance when you travel, adding still more
clutter to the adapter and cable collection already required by your
camera and PC. One advantage of chargers that use a the brick and cord
type of adapter is that they often accept a “car cord” that plugs into a
car cigarette lighter outlet (more on this below).
Charge control. Any battery charger
that charges batteries at a reasonable fast rate, needs a way to stop the
charge cycle when it�s complete so the batteries are not
overcharged. The worst thing you can do to your batteries is
overcharge them. The way to prevent this is to use a microprocessor
controlled smart charger that monitors the battery charge and knows just
the right charge for them. Avoid chargers that charge for a fixed length
of time, regardless of what’s needed. These 5 or 8 hour “rapid chargers”
deliver the same charge to every set of batteries regardless of how much
charge they actually need. Their only control is a simple on/off timer.
One of these chargers is like a coffee shop waitress who refills
everyone’s cup at your table with 8 ounces of new coffee, no matter how
much is left in each cup. These chargers cause problems two ways:
If you insert fully charged or partially charged batteries
into the charger it has no way to sense this, so it gives the batteries
the full charge it was designed to deliver.
If you interrupt the charge by pulling the plug and then
plugging it back in, a complete charge cycle starts again, even if the
previous charge cycle was almost complete.
The best way to avoid these scenarios is to use a smart
charger with microprocessor control. The most sophisticated types of
actually have separate circuits to monitor the charge level of each
individual battery being charged. A smart charger can determine when a
battery is fully charged and then depending on its design, either shut off
entirely or switch to trickle charge. The point of the trickle charge is
to keep the battery fully charged without overcharging it.
Dual
voltage. If you will be traveling in other countries that don�t
have the US standard AC power, a charger that also works with 220 or 240
volts AC is nice to have. Chargers that use an AC brick and cable often
have the special AC adapters available as an (expensive) option. Some
plug-in chargers automatically work with either voltage.
LEDs
and Audible Alerts. LEDs are standard on most chargers. They
make it easy to tell when the charge cycle is complete or if the batteries
haven’t been inserted correctly. Audible alerts on some chargers are nice,
but they certainly aren�t a must have.
Car cords. Some chargers that use an AC
power brick also have an option to use a car cord. Although these may be
useful at times, you’d probably be better off carrying a spare set of
batteries in a battery
wallet and charging them at night.
“Trickle” charge. All but the least expensive
chargers now provide a trickle or pulse charge mode that maintains the
batteries� charge after the normal charge cycle is complete. Many battery
manufacturers do not recommend trickle charging. To be safe, fully charge
your batteries and store them in the freezer.
Conditioning Circuit. Some
smart chargers also have a “conditioning” circuit. This is basically just
a discharge circuit, which discharges the batteries before it charges
them. It can be useful to help prevent the voltage depletion effect that
occurs in NiCad batteries, but it�s not too important for NiMH batteries.
The only time it�s really useful for NiMH batteries is to quickly
condition the cells when they are brand new. Since it takes a few
charge/discharge cycles for NiMH batteries to reach their full capacity, a
conditioning circuit makes it easy to run the batteries through a few
cycles.
Once your batteries are charged, the goal is to keep them
that way as long as possible. When you are out of battery power, you have
to stop shooting. There are ways to prolong your battery’s charge. In this
section we discuss some of them.
When you first get new
rechargeable batteries, charge and discharge them a few times so they get
fully charged.
When photographing, turn off
the power hungry LCD monitor and use the optical viewfinder. It’s better
for taking pictures anyway. When you have to use the LCD monitor, turn
down its brightness, or use the black & white mode if it’s available
on your camera.
If it’s cold out, keep the
camera or batteries under your coat to keep them warmer. Cold batteries
deliver less power and die faster than warm batteries.
Confused?
In one place you read that batteries retain their charge longer
when stored in a cold freezer, and in another place you read that
you need to keep them warm to prolong their charge. What gives? Well
if you think about batteries as small chemical engines, it all makes
sense. When batteries are cold or frozen their chemical reactions
slow down and the batteries will keep their stored charge longer.
However, if you try to use the batteries when they are cold, there
isn’t enough of a chemical reaction to generate the power you need.
Warming them up speeds up the reaction and gives you more power to
draw on.
If the camera is set to
full-time autofocus, you’ll hear the lens “hunting” for a focus point when
you point the camera in different directions. To conserve power, switch
full-time autofocus off so the camera only focuses when you press the
shutter button halfway down.
If using NiCad batteries,
fully drain and recharge them periodically. The easiest way to do this is
with a conditioning charger that drains the batteries before recharging
them, or a pulse charger that uses a negative pulse to remove the gas
bubbles that build up on the cell plates.
Occasionally clean the
battery contacts in the camera and charger with a cotton swab and rubbing
alcohol (isopropyl alcohol). Most charging problems are caused by dirty
contacts on the battery or charger.
When not using the camera
for an extended period, remove the batteries and store them in a cool, dry
place. (Also remove flash memory cards from the camera when not in
use.)
NiMH and NiCad batteries
start to lose a few percentage points of power a day when stored at room
temperature. But they will retain a 90% charge for several months if you
keep them in the freezer after they are fully charged. When freezing them,
put them in tightly sealed bags so they stay dry and also let them return
to room temperature in the same bag before using them.
When using the camera to
display, print, or download images, use an AC adapter so the batteries
aren’t being drained.
Batteries don’t last forever. Depending on their type, they’ll last
between 400-700 recharge cycles. For heavy users that’s about 1 to 2
years. Generally, you can tell they are failing when they no longer hold
as long a charge.
Carrying and storing your
batteries
There’s nothing more disappointing than having your batteries die just
when there are important photos to be taken. The only way to prevent this
is to have spare battery sets with you at all times. However, this
presents a carrying and storage problem that can be solved with Battery
Wallets� and a Battery
Caddy�.
To make it easier and more convenient to carry batteries, you use a
battery wallet that slips into your purse or pocket or attaches to your
belt. Not only do battery wallets make batteries easier to carry, they
also make them easier to store. Battery sets should be charged and used as
if they were a unit throughout their life and these wallets make it easy
for you to keep them together. (Tip: When charged, put batteries in the
wallet right side up. When dead, insert them right side down. This way
you’ll always know which battery sets are charged and which aren’t.) Some
photographers keep a set of AA Lithium batteries in a wallet as a
permanent backup. Not only do they have three times the capacity of
alkaline batteries, they have a shelf life of 10 years!
At home it’s easy to misplace your batteries. Letting them just roll
around on the counter isn’t the ideal solution. It’s easy to mix up the
sets and it can be dangerous if the batteries short out on each other. To
keep them organized, you need a desktop battery caddy. Like a wallet, a
caddy keeps battery sets together and makes them easy to find. Just as
with the wallet, when charged, put batteries in the caddy right side up.
When dead, insert them right side down.
Unity Digital�s ProPower Pack ” is an external battery pack containing
NiMH batteries that deliver 2700 milliamp hours of sustained power. The
battery pack clips onto your belt and a cord connects it to the camera.
One side benefit is that you can remove batteries from the camera and
lighten it a lot. If you choose to leave them in the camera, they will act
as a reserve when the battery pack starts running low on power. When the
camera�s battery indicator tells you the batteries are running out,
disconnect the ProPower Pack from the camera and the internal batteries
will automatically take over. A battery charger and lightweight cables
that connect the camera to the ProPower Pack are included.
When flying, be sure your batteries are charged. You may be asked to
turn the camera on at a security check point. Also, be sure you can
recharge your batteries. In the US, the power system is 120 volts and
60Hz. Overseas it’s 220 or 240 volts and 50Hz. On top of this, there is a
wide variety of wall plugs. To plug in battery chargers, AC adapters, and
notebook computers, you need an adapter kit: preferably a universal plug
and voltage adapter.
Converters can harm appliances over time and shouldn’t be used for more
than a few hours at a time. Transformers can be used for longer periods.
The only problem with transformers is that they are much heavier than
converters.
You are sometimes off the road, perhaps on a canoe trip, and need to
recharge your AA rechargeable batteries. To do so, you need a solar
battery charger. These charge batteries very slowly (as long as 12 hours
of direct sunlight for a full charge), but when you have no choice, they
are a lot better than nothing.
According to the EPA, each year over 2 billion used batteries are
disposed into solid waste facilities in the United States. This
constitutes 88% of the highly toxic mercury and 54% of the cadmium
deposited into our landfills. Many kinds of batteries, like those used in
digital cameras, can be recycled instead of thrown away. When they wear
out, try to take them back to the store where you bought them. Many stores
collect the used batteries and then send them to a factory to be recycled.
NiCad batteries use Cadmium, a highly toxic heavy metal, that can damage
the environment if not disposed of properly. (They should be recycled; not
discarded). NiMH (Nickel Metal Hydride) batteries are the most
environmentally friendly batteries because they are made from non-toxic
metals.
Can I use my NiMH batteries in
other devices?
Once you have an investment in batteries for your
camera, the question soon arises, “Can I use them with other
devices?” Yes you can. For most high drain electronic applications
NiMH batteries are ideal substitutes and you needn’t worry about the
apparent voltage differences. Even though alkaline batteries are
rated at a nominal 1.5 volts, they only deliver 1.5 volts when they
are fully charged. As they begin to discharge the voltage of
alkaline batteries continuously drops. In fact, over the course of
their discharge, alkaline batteries actually average about 1.2
volts. That’s very close to the 1.2 volts a NiMH battery retains for
most of their discharge cycle.
There are a couple of cases where actual voltage
difference may be important to you. In the case of a device like a
radio, where a higher voltage can mean a stronger signal, a fresh
alkaline battery may be more desirable -but more expensive- than a
rechargeable NiMH battery. This is also true for a flashlight, which
will be brighter with the initial higher voltage of alkaline cells.
These minor difference may not be important to you and are probably
offset by the much lower cost of operating NiMH batteries.
The one time when the voltage differences of the two
is important is in the case of a device checks the voltage of a
battery to estimate the amount of charge left on the battery.
Because the voltage of an alkaline battery drops at a very
predictable rate it’s possible to estimate the amount of capacity
left in an alkaline battery based solely on its voltage. (1.5 volts
– fully charged, 1.25 volts – 50% charged, 1.0 volts – almost fully
discharged). But a NiMH (or NiCad) battery stays at about 1.2 volts
until it is nearly completely discharged. This makes it almost
impossible to know the amount of capacity left based on its voltage
alone. (When a device that’s using NiMH batteries indicates the
battery is low, it’s time to change the batteries
now)!
- An adapter is used to plug a dual voltage appliance, converter, or
transformer into a wall outlet that doesn’t match the device. - A converter is used with electric appliances such
as hairdryers. - A transformer is used with electronic devices such as
computers.
| The Glossary of Batteries
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