10 most important things to know about batteries

10 most important things to know about batteries Page 1
http://videoexpert.home.att.net/artic1/225cbat.htm 09/11/2004 07:44:02 AM
225c
THE 10 MOST IMPORTANT THINGS TO KNOW ABOUT BATTERIES
1. Buy several batteries; like potato chips, one is never enough.
With several batteries, some can be charging while others are being
used. Also you can fill your pockets with several batteries so that
when one dies you have another to quickly replace it.
2. If you shoot infrequently (like once a month or less), use lead
acid (gel cells) to power your camera. Gel cells are relatively
inexpensive, and once charged, retain their charge for long periods of
time without self-discharging. After using a gel cell, be sure to
recharge it immediately; if left discharged, the components inside
will sulfate and self-destruct leaving you with a useless battery
after a couple of days.
3. If you use your camera frequently, use NiCad batteries. They
recharge many times, and hold a large amount of current per pound of
weight. Most can be "quick" charged within a couple of hours allowing
you to keep up as other batteries are used.
Remember that NiCad batteries perform poorly when cold and
should not be recharged when very hot or very cold. Handle NiCads
gently. Although the exteriors may look fine, concussions can damage
the sensitive interior of the batteries causing internal shorts which
bleed the life out of the batteries as they sit.
4. Whenever possible, recharge NiCad batteries the day before they
will be used. NiCads in good condition generally lose about 2% of
their charge per day as they repose on the shelf. Batteries with mild
10 most important things to know about batteries Page 2
http://videoexpert.home.att.net/artic1/225cbat.htm 09/11/2004 07:44:02 AM
internal shorts drain themselves even faster. A NiCad with a serious
short (drains itself dead in one day on the shelf), may still be quite
useful to you; charge it immediately before use, then put it right to
work. You will drain the power out of it before it drains itself.
5. NiCad memory is a curse primarily of consumer and prosumer gear.
NiCad memory is a condition that occurs when you have used the battery
for a short period of time and then recharged it, used it again for a
short time, then recharged it, and repeated this process a number of
times. Eventually the battery "forgets" its original capacity
(perhaps 30 - 50 minutes), and only operates your camera for a short
period of time (perhaps 10 minutes). The memory is due to a chemical
change causing cells in the battery to reduce their voltages by about
10%. Consumer camcorders often have circuits which require 10.5 volts
from the 12 volt battery. When the battery goes below this voltage,
the mechanism shuts down. If the battery has memory, or one or two
cells are weak for some other reason, it is very easy for the voltage
to reach the cutoff level causing shutdown. For this reason,
consumers and professionals need to "exercise" their batteries, making
sure that they perform long duty cycles. There are also devices that
discharge and recharge NiCad batteries to exercise them, reducing the
memory effect.
Professional video gear is less susceptible to memory problems.
Battery packs often contain eleven or twelve cells creating 13.2 or
14.4 volts for a camera that needs only 11 volts to operate. The
camera's power circuit uses only the voltage it needs, disregarding
the extra. If one cell in a 14.4 volt battery goes awry, there are
still 13.2 volts remaining to power the camera. If the NiCad cells
develop a memory, losing 10% of their oomph, there are still about 12
volts coming out of the battery pack; the camera remains happy. The
battery pack is truly expended when its voltage drops to 11 or so
volts.
6. If you use a lot of batteries, team them up with a "smart" charger
designed for the batteries (Anton Bauer, Cine 60, Frezzi). These
NiCad batteries have sensors to determine whether the batteries are
overheating while charging and whether the batteries have reached
their full potential. Meanwhile, the smart charger is monitoring each
cell's temperature (being careful not to overheat and damage any of
the cells), while also monitoring each cell to assure that all get
10 most important things to know about batteries Page 3
http://videoexpert.home.att.net/artic1/225cbat.htm 09/11/2004 07:44:02 AM
recharged.
7. Rotate your batteries so that some don't do all the work while
others sit idle; they all need exercise.
8. The lithium batteries that power some camcorders recharge
quickly and appear to have no memory problems but are more
expensive.
9. If your gear gets wet, especially in salt water, remove the
battery first, and do it immediately. Once the salt water gets into
the circuits, there is no way to turn the machine off and it will go
into rapid meltdown.
10. Power your lights on a separate battery from your camera. Not
only will both shoot longer, but cameras refuse to work with weak
batteries, whereas lights don't care. There's no sense having your
lights drain off the camera's "good" power, and be able to operate for
a half hour more after your camera shuts down.
About the author About Today's Video 3rd. ed. Return
home