Just a few years ago, our battery options were largely limited to
disposable alkaline batteries and NiCd rechargeables. Neither type
works very well with digital cameras and related gear. Today’s
rechargeable NiMHs and Li-ions, as well as lithium disposables,
usually are a better choice. Although your choice of battery can
be limited by what your device accepts, understanding your battery
type can help you get the most out of it.
NiCd. The old rechargeable standard, these batteries are known for
their limited capacity. They also have “memory” effects,
which seriously degrade performance and the battery’s life
span: Unless the battery is fully discharged before recharging,
the battery’s capacity will go down with every recharge cycle
until it’s useless. NiCds contain cadmium, a heavy metal that’s
decidedly unfriendly to the environment. While NiCds still work
nicely for power tools, they’re not your best choice for photo
NiMH. The first real alternative to alkalines and NiCds, NiMH batteries
can store as much as 40 percent more energy than NiCds, and they’re
far more resistant to cold than alkalines, providing superior capacity
in those conditions. NiMHs don’t suffer from memory problems
like NiCds, so you can freely recharge them without needing to drain
them all the way first. Since NiMHs can be recharged about 500 times,
they cost next to nothing to run.
In flash units, NiMHs recycle your flash in half the time than fresh
alkaline batteries. Unlike alkalines, NiMHs’ recycling times
won’t get longer and longer as the battery’s charge
is used up.
So what’s the catch? Like all rechargeables, NiMH batteries
may lose 1 to 2 percent of their charge per day just sitting in
your camera bag. If you charge your battery and let it lie around
for a few weeks before you use it, you’ll only get a fraction
of the shots you were expecting. Let your batteries sit longer between
uses, and you could come back to a discharged battery.
Li-ion. These batteries have terrific capacity, they’re much
smaller and lighter than other batteries that hold the same energy,
and they’re even more resistant to cold than NiMHs. Like NiMHs,
they’re free of memory problems, and they can be recharged
up to 1,000 times.
Li-ion batteries also self-discharge and will need to be recharged
after sitting for several weeks. These batteries require a dedicated
charger; if you use a third-party unit, make sure it’s compatible
with the battery you’re charging.
Alkalines. While alkaline technology isn’t at all new, it
works well enough in flash units and other devices that get only
occasional use. Alkalines aren’t the best choice if you’re
going to be shooting lots and lots of images, but they do have some
advantages: Unlike rechargeables, you always can buy more of them
at the supermarket—or in the Grand Canyon—and they’re
Digital cameras drain alkalines quickly, making the batteries costly
to use if you shoot a lot. In flash units, recycle times increase
dramatically as the batteries are used up; before the alkalines
are spent, you’ll wait twice as long or more for the “flash-ready”
light to come on.
Lithiums. Disposable lithiums greatly outperform most other batteries.
Although lithium disposables cost a little over twice the price
of an alkaline battery, they last about three to five times longer
than the alkalines do in digital cameras and electronic flash units.
Like the rechargeables, lithiums recycle your flash unit quickly
and maintain most of that speed until they’re used up. They
share Li-ion batteries’ resistance to cold and can deliver
the bulk of their capacity even in freezing weather.
Lithium disposables also have about double the shelf life of alkalines—if
your camera can use them, disposable lithiums make a great backup
Whichever battery you choose, how you use your camera and the type
of pictures you take can affect battery life. One of the best things
about digital photography, the LCD monitor, also is among the hungriest
for battery power. Turn your camera off when you’re not using
it, and keep image review times as short as possible.
For those of us making time exposures at night, keeping the shutter
open—and the sensor live—for long periods eats power
more rapidly than quick handheld shots. Cooler temperatures at night
don’t help power consumption either—if you do a lot
of this kind of shooting, make sure to have spare batteries on hand.
“Is It Dead Yet?”
Except for alkaline batteries, which put out less and less power
as they’re discharged, other battery types put out a fairly
constant voltage until they’re nearly exhausted. That’s
generally good news, as it means your gear will keep working consistently
while the batteries have juice, but there’s a downside. The
first is that apart from the alkalines, there’s little warning
of impending battery exhaustion—your batteries can produce
normal power levels one minute and be dead shortly thereafter.
Because most battery-check indicators rely on output voltage to
estimate batteries’ remaining strength, the indicators in
your camera aren’t much better at predicting battery exhaustion
than you are. At best, they can merely report that you’re
“nearly” exhausted, just before the battery quits.
At their worst, battery-strength indicators can be fooled by unusually
heavy drains on the battery—the indicators sometimes can report
your battery is nearly dead when it isn’t. These heavy drains
can come from repeatedly rapid-firing your camera through a large
number of frames and by operation in cold weather. Under these circumstances,
the battery indicators can show a depleted charge, but the batteries
come back to life some time after the load is removed or after the
batteries warm up.
While you also can “rest” batteries that really are
nearly exhausted, don’t do it. You risk losing your images—and
rendering your media card unreadable—if the battery dies while
the camera is trying to write to the card. Using rechargeable batteries
that are that close to being completely discharged shortens their
life, too. It’s always a good idea to keep a spare battery
Charging Your Batteries
Although Li-ions and NiMHs have eliminated the NiCd’s memory
problems, there still are a few things you can do to help the batteries
last longer and deliver maximum capacity. The first is to prevent
them from becoming deeply discharged—exhausted to the point
where internal damage occurs.
Along with ignoring the urge to squeeze out just one more shot from
batteries that need recharging, make sure the batteries’ charge
levels don’t drop too far while they’re in storage.
It’s a good idea to top off your batteries at least once a
month, whether you’ve used them or not. Some camera makers
offer a dock that keeps your camera battery fully charged automatically—the
docks maximize your batteries’ longevity while making sure
you’ve al-ways got a camera that’s ready to go.
In the past, the heat generated by overcharging batteries was a
threat to battery longevity, but modern chargers use a more advanced,
three-stage system to prevent this problem. Avoid using older fast
chargers with your NiMHs, or chargers for other kinds of cells.
If you’re going out to buy a new recharger, keep in mind that
the faster ones generally get your batteries hotter in the process,
shortening their life somewhat. Whether the extra convenience makes
the batteries’ shorter life span worthwhile is up to you.
Li-ion batteries have dedicated chargers, so you don’t have
to worry about overcharging them or how fast a charger to get—just
use the charger designed for the battery. Li-ions and NiMHs have
one special need, though, and that’s to condition them by
fully charging them before the first use, then discharging them
all the way before recharging. Repeat this cycle three times, and
you’re good to go—you’ll get the best out of the
batteries, and you can recharge them whenever you want to.