Dual Battery Systems

Dual Battery Systems
TECH TALK
TECH TALK
Dual Battery Systems
ESSENTIAL TIPS
Motoring enthusiasts have been using
and charging auxiliary batteries in
their 4WDs and caravans with varying
degrees of success for nearly a century.
With modern demands such as fridges,
winches, phones and DVD players, a
modern solution is required, rather than
the special dashboard DIY rigged switch.
TIP 1
TIP 2
Why fit fuses to both batteries using a
battery isolator?
How to avoid voltage drop?
Any wire connected to a battery must be protected from
electrical shorts. A short-to-ground will draw current only
limited by wiring resistance and battery capacity. This
can melt the wire and may result in a fire. The simplest
protection is a fuse. A fuse on only one battery will
protect that battery, but not the wire, because the
other battery can still melt the wire.
As demands on batteries have
increased, so too has the need for a
switch designed specifically for use in
multi-battery applications. The need for
a solenoid priority system to protect
the start battery from being excessively
discharged by auxiliary loads, while still
allowing the auxiliary battery to supply
non-essential loads, is all-important.
Your biggest unforeseen problem is voltage drop when
charging from your alternator. Your 4WD will need to have
the highest possible voltage in the auxiliary battery. This
will allow it to charge as quickly as possible, and as fully
as possible. This can be achieved by using at least 15mm
copper cables. It may be more expensive, but when you
are stranded in remote bush, you need a battery system
that you can count on.
Remember, the larger the current draw and the greater the
distance to your batteries, the greater the cable thickness
needs to be.
Some common sense is needed when installing a second
battery. Ensure it is strapped down in an approved battery
carrier/tray. Always mount it in a well-ventilated area,
such as engine bay or on your chassis. Do not install your
second battery in your van, under a seat or near other
equipment like inverters.
When looking for a dual battery system,
do not look for the cheapest and
smallest battery. Be sure to buy one
big enough to handle the job required,
remembering that batteries do not like
to be discharged and run flat.
Always ensure all wiring is protected by tubbing. There’s
nothing worse than a cable rubbing on a sharp corner and
shorting out your 4WD.
When assessing dual battery
systems, look for:
• Space and capacity for dual batteries
in your vehicle.
• What accessories you are running.
• What your alternator condition and
output is.
• Your 4WD needs – weekender,
long distance tourer, hard-core.
• Quality copper cable and terminals.
• Switches that run cooler.
• Solenoids that use less power.
• Fault indicating codes on LEDs.
• Can you jump start with the system?
• Protected battery terminals to
minimise shorting or voltage loss.
• Select a unit’s amperage catering
for your needs.
• Surge protection.
• Warranty and technical backup.
16
JULY 2009
For most 4WD set-ups the best option
is to use a voltage sensitive relay
activated solenoid. Australian made
Redarc is of one such unit. With over
30 years experience in the field both
in Australia and overseas, they
do an exceptional job.
The Redarc Smart Start® SBI is a
microprocessor controlled Smart Battery
Isolator. Put simply, once the start
battery is charged by the alternator,
the Smart Start® SBI will connect an
auxiliary battery to the charge circuit.
Similarly, if the start battery voltage
drops too low, the Smart Start® SBI will
disconnect any auxiliary batteries or loads
to conserve charge in the start battery.
Once in use the Redarc will check
that both your batteries are being
charged up to 13.2 volts. Once you
turn the motor off and start using your
accessories the Redarc will isolate
your starting battery at 12.7 volts.
This delivers the peace of mind you
are looking for when you are out
and about camping.
Nissan
FLASHBACK
BACK 1969
Fairlady 240Z
The first-generation Fairlady Z, launched in November 1969 (announced in October) was
available in the high-power 432 model equipped with the same 6-cylinder in line DOHC
24-valve S20 engine (160PS) as the Skyline GT-R (PGC10). The name
’432’ refers to 4 valves, 3 carburettors and 2 camshafts. Magnesium
wheels were fitted as standard.
ADDITIONAL SPECIALTIES
• The Smart Start® SBI is
Microprocessor Controlled to
ensure the best charge for your
auxiliary battery – set and forget.
• It is Australian designed and
manufactured and supported by
a ‘No Fuss’ Two Year Warranty.
• Smart Start® SBI Over-Ride.
The Smart Start® SBI features
an over-ride wire
allowing starting from
both batteries in the
event that the start
battery alone cannot
start the vehicle.
• The Smart Start® SBI is the only
Dual Battery Isolator available in
Australia to feature ‘Power Saving
Technology’. This means the unit
runs significantly cooler and uses just
0.15A when engaged.
• The Smart Start® SBI can be
used in conjunction with
dissimilar battery types
for example Gel, AGM,
Calcium and/or
Standard Lead Acid
type batteries.
• LED Status Indication. The Redarc
Smart Start® SBI features LED fault
indication.
• Free Redarc technical
advice and support
throughout Australia.
Nissan would like to thank Redarc
for contributing to this article
www.redarc.com.au
JULY 2009
17
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