Welcome to the May issue of
apologise for the late circulation of this particular issue and
bear with us through this rather busy period. Summer is
industries most active period.
month we look at Switch Tripping Battery Chargers. Widely
industrial applications, they are the life blood of many
therefore extremely important. But what is switch
your battery installation fall into the standby or cycling
batteries in the correct manner for a given duty is vital. Get
and the cells could boil dry or discharge. Either way, they
job they were commissioned to do and you'll end up out of
feel free to submit articles or questions. Dispite our industrial
more than happy to answer questions from any of our
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
ARTICLE: Switch Tripping Battery Chargers:
tripping battery chargers are the most popular system used
applications worldwide. They are more
often desiged as low power chargers maintaining
sealed lead acid
batteries configured for short duration high current
is switch tripping?
Tripping is a term used to describe loads of a pulsed nature.
contactors and solenoids would be typical
examples of components that may
employed in an application of this type.
often than not, any standing loads on chargers of this nature are
comparison to the switched loads which may have a short
duration high current
requirement. Batteries must be sized
accordingly and since sealed lead acid cells
to deliver a lot of current for their size, they are often utilised.
well though, of course.
In some cases, the performance of a
switch tripping system is critical and
still, lives could be in jeopardy where failure occurs. For absolute
more systems are sometimes used to eradicate
single point failure.
of this type may be referred to as a dual
redundant charging systems.
free supply is the preferred power source in the majority of
has a direct bearing on unit cost. A switch tripping charging system
generally more expensive than a
conventional battery charger, even an automatic
number of alarms are normally included to provide an advanced
mains failure or charger failure occur.
course, there are other factors to consider too. The end discharge
calculated in order to select the most appropriate charging regime.
is configured differently to a cycling system for a very good
discharge determines which of the two is the most appropriate in
terms of current
will be looking at this aspect of battery charging in more
detail in our next article.
tripping battery charging equipment is available from most
chassis or enclosed versions. Additionally, many will custom build
the system to
exact specification. It is simply a question of determining the
total load, the
(back up time), the operating temperature, the duty cycle (how much
available to recharge the batteries) and the end discharge
Batteries are often supplied with the
charger as a package. The batteries may be
inside an enclosed system in its coolest point, the lower half,
charging equipment located in the top
half. Any other arrangement wouldn't work
due to temperature fluctuations within the
cubicle. Indeed, We have
witnessed a number of
failures over the years due
to batteries being located next to
sink or transformer. Don't do it if you value your cells
and where possible,
metal barrier to segregate the charger from
when placing an order for a switch tripping charging system,
don't be afraid
questions. Reputable suppliers will be only too pleased to help you
want a system that works well, communication between you and your
A new concept in battery
Current discharge characteristics for easy battery
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the guesswork out of battery capacity factory acceptance
ARTICLE: Standby or Cycling. Author: Alan
to decide if an application falls into the standby or cycling
category is very
important if you want reliability. If the
wrong charging regime's is used, the
will never perform to specification and disappointment and cost will
not unusual for an application to fall into both of the above at
course and this identifies a further problem, what type of
charger is suitable in
let me explain briefly the differences between the two operating
is a term used to describe a battery installation that spends most
of its life
full charged state with minimal loading. A typical example
would be an emergency generator battery which may
not be used for years at a time apart from an occasional
run, electrical supplies are so reliable these
is a term used to describe a charger and battery system connected to
more frequent nature, weekly or even daily in many cases. The
battery works much
compared to the standby version and requires a different charging
recover to 100% of its rating every time.
reliable battery charger must be correctly configured for the
application in which
it has to function. A standby charger
can be a simple constant potential system with
charge characteristic and little else in the way of complicated
cycling charger will require a fixed period at a raised
charging voltage to approximate constant current mode at
the beginning of the cycle. This is followed
by a taper charge
a fixed time period has elapsed or
when a particular battery voltage is
are slight variations on this but by and large, this is how it
Voltage Alarms are often employed to differentiate between a partial
full one so that the appropriate charging regime can commence. This
always employed where the duty flips between standby and
course, the charger must be designed to recharge the batteries as
manufacturer. Every single one of them will factor temperature into
must do the same. If the installation has to operate in a room
with wildly fluctuating
temperatures, the charger must include battery temperature
important than almost anything else in my opinion.
probably categorise every battery application you see into the
standby or cycling
if you follow the guidelines above. Standby is precisely that, the
system is ready
provide emergency power should it prove necessary but probably won't
have too. Cycling
charge and discharge, charge and discharge in an endless cycle.
application is the first step to success.
Remember: Look after your batteries and
your batteries will look after you!
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Questions from Roger
What is a shunt?
A shunt is resistive device used to
generate a small signal voltage
display current on a moving coil ammeter. Charging current is
the shunt and the signal voltage is
a current transformer?.
transformer are used to measure current in ac
isolated devices manufactured on an iron ring core
central hole through which an ac cable is
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