|
EDITORIAL.
Welcome to our August
issue of DC Supply.
This is
the first issue of the second year of our publication, DC
Supply.
Many of
you have been subscribing since our first issue was
released
and we
hope that you have found the articles we have produced up
to
now,
useful.
Please
note that we will no longer be posting a copy of each
months
publication to our website. It is becoming
increasingly difficult to update
the site
on a regular basis and this is leading to issue
delays. You will
continue
to receive your copy on a subscription basis for as long as
you
wish of
course.
This
month we look at temperature compensation and automatic
boost.
Batteries, lead acid in particular, must be
maintained at a specific voltage
to get
the best performance from them. Our article on
temperature
compensation will show you how to make
sure your batteries perform
regardless of temperature
fluctuations.
Boost is
a feature often required on charging systems. Often the
facility
is
manually operated but there are applications in which an
automatic
boost
facility is required. Take a look at our second
article where we
explain
where, how and why auto boost is required.
We hope
you enjoy this months issue.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Editor: Alan Fidler.
Alan is the owner and manager of CBC
Design, a leading battery management company
based in the UK. He has worked in the
industry for over nineteen years and has designed
charging equipment and battery monitors for some of the world
largest companies.
_____________________________________________________________________
_____________________________________________________________________
ARTICLE: Temperature Compensation: Alan
Fidler.
In some
environments where ambient temperatures vary over a wide range,
batteries
cannot
perform to the best of their ability unless the charging voltage is
raised or
lowered
in accordance with a fall or rise in
temperature.
Typically, a lead acid battery has a
compensation value of about 2.5mV per cell per
oC
depending upon the battery type. This would
mean a 12V battery charged at 2.26 volts
per cell
at 25oC would require a charging voltage of approx 13.75VDC at 15oC
and
13.9VDC
at 5oC. In all cases, the charging voltage increases as the
temperature falls
and visa
versa.
Sadly,
temperature compensation is rarely used and the result is premature
failure
of hundreds of thousands of batteries
worldwide. This may be good news for
battery
suppliers but is certainly bad news for us
and the environment too. The facility is
often
inexpensive, consisting of nothing more
that an RT (resistor/temperature) matched
probe
connected to the charger control
circuit.
Certainly long life batteries designed
to operate for 7 years or more must be properly
charged
at the most appropriate level. They will never perform to
specification if the
float
voltage is too high or too low for a given ambient and the result
will be premature
failure.
If you use 7 or 10 year life batteries in your
installation and they fail before they
should,
look at the charging method and take ambient temperature readings.
It may be
that your charging equipment
needs to be temperature compensated.
Contact
your charger supplier and ask them if temperature compensation can
be
retro
fitted to your installation. If not, you may need to adjust your
charging voltage
manually, depending upon the temperature.
Reputable battery manufacturers will
be able
to provide you with the actual charging potentials required for a
given
temperature.
One
thing is certain, a lack of compensation on a battery installation
subjected
to wide
temperature variations will be detrimental to the health of
your cells. They
will
fail well before they should and you'll be throwing money
away.
Remember: Look after your batteries and
your batteries will look after you!
______________________________________________________________________
______________________________________________________________________
CLASSIFIED ADS:
*** NEW!
Electronic Constant
Current Battery
Dischargers***
A new concept in battery
discharging equipment!
Constant
Current discharge characteristics for easy battery
analysis!
Wide
operating range from 20-130VDC for true
flexibility!
Available in low and high power
versions!
Takes
the guesswork out of battery capacity factory acceptance
tests!
new
products
page!______________________________________________________________________
______________________________________________________________________
ARTICLE: Auto
boost. Author: Alan Fidler.
Most of
us are familiar with the word boost but for those of you who
are not, it is a
term
used to describe a condition under which the charging voltage is
raised to
increase
current into the battery, i.e. boost.
Most
boost facilities are included for equalisation purposes. It is
unfortunate that
batteries connected in series have a
tendency, over time, to become slightly
unbalanced. Boost corrects this by taking
the battery to a specific potential
that forces each cell to display the
same on charge voltage, i.e, equalisation.
The
boost function is often manually controlled using a simple
switch.
As well
as the manual boost system, an automatic boost system is also
used
in
applications where some degree of automation is required. The two
most
widely
used boost systems include semi or fully automatic
boost.
Semi
automatic boost is used in an equalising role. The boost function
is
manually
initiated and a timer switches the charging system back to
float
mode
after a pre-set period. This sort of system is used one a month as
part
of an
established maintenance regime.
Fully
automatic boost systems tend to be used on batteries which
require
a high initial charging
voltage that switches down to float when the
battery
reaches
a pre-set potential or a timer operates, whichever comes
first. This
type of
boost facility is particularly suited to applications where the
batteries
are
subjected to deep discharge.
More
complicated automatic boost systems include voltage monitors
which
determine if and when the boost facility is
required. An battery installation
that is subjected to both deep or
partial discharge will not necessarily require
boost on
every charging cycle. The depth of discharge determines if and when
to
activate the boost function to
prevent excessive gassing following a light
discharge
cycle.
In all
cases, consult the battery manufacturers documentation to
determine
if and
when a boost facility may be required. Using boost unnecessarily
will
damage
your batteries and invalidate the warranty. It is worth noting
that
temperature compensated chargers are rarely
fitted with boost.
______________________________________________________________________
______________________________________________________________________
CLASSIFIED ADS:
*** NEW! 110 & 230V AC Table & Bedside
Lamp
Dimmers***
At last, a dimmer that is easy to fit to any table or bedside
light!
Available exclusively from the
manufacturer!
Adjusts lamps from a dim glow to
bright light at any rating up to 100W!
Useful
for unobtrusive bedside lighting!
Available in 110/115 or 220/230V
Versions!
order your dimmer
NOW!
______________________________________________________________________
COMPETITION:
Subscribe to our ezine and you
will be automatically entered into our competition where you can win
a FREE Nicad "AA" battery pack.
Simply send your email
address (No free email) to cbc_design@btconnect.com with the words
"SUBSCRIBE" in the
subject line.
______________________________________________________________________
READERS QUESTIONS.
Questions from Damon
Wood!
Question 1.
What is an
accumulator?
An
accumulator is a battery. The term accumulator was widely
used
in the
past and has been replaced by the term battery.
Question 2.
What is
a Controlled Rectifier?.
A
controlled rectifier is a half or full wave bridge rectifier which
converts
AC
into DC. Unlike un-controlled rectifiers, a controlled type can
be
used to regulate output current and/or
voltage. They are widely used
in
industrial charging applications.
______________________________________________________________________
SUBSCRIBER
ADS
"Discover The Amazing System for Creating Your Own Hot Selling Information
Products" Expert Product
Developer Gives You The Power
to Profit From Your Knowledge!http://www.linkcounter.com/go.php?linkid=253522
...................................................................................................................................................................
===> STOP BUILDING YOUR MINI SITES THE HARD WAY!
<==
At last...the software you've been waiting for! A quick and
easy way to create
professional
looking mini sites in minutes.
Check out http://forward.at/minisites
...................................................................................................................................................................
NEVER BEFORE REVEALED! eCover Generator!
Now anyone can create THEIR OWN ECOVERS. This AMAZING SOFTWARE does all
the
work for you. http://www.linkcounter.com/go.php?linkid=223681
..........................................................................................................................
Submit your ezine, articles, and
free ezine ads to 500+ directories. Free trial Download now...
Satisfaction Guaranteed!
http://wetrack.it/eza/af.cgi?43
..........................................................................................................................
HOW you can generate 50-200+ targeted opt-in
LEADS or SUBSCRIBERS a
day with this
proven system... These is
Your secret weapon for rapidly building a massive
opt-in email list. http://tinyurl.com/v76
______________________________________________________________________
UNSUBSCRIBE.
This ezine is sent to companies
or individuals who have chosen to subscribe to "DC Supply". If you
wish to unsubscribe, send an email with the words "UNSUBSCRIBE" in the
subject line and we will cancel your subscription.
______________________________________________________________________
"You may distribute this ezine to whomever you wish as long
as it is sent in its entirety."
(c) copyright 2002 CBC Design.
Subscribe TODAY!
by sending an email
with "SUBSCRIBE" in the
subject line.
|