Hi guys, Briohny here from Accelerate Auto Electrics
and Air Conditioning.
If you're heading off-road in your four-wheel drive
and going camping, one of the must-haves
to keep your food and drinks cold
and your gadgets powered is a dual battery system.
Unfortunately, you can't just come on in
and purchase a second battery,
and plug the fridge and devices into it,
as you run the risk of running it flat,
and worse still, running your starting battery
in your car flat, so your car won't start.
When looking at buying a dual battery system,
we recommend that you do do some serious research
and planning before you install it.
You need to ensure that you have enough power
to keep your fridge and all your devices powered
and still start the car.
One of the most common questions we get asked
when chatting to customers about dual battery systems
is what the difference is between a smart isolator,
DC to DC charger, and battery management system.
We have put together this series of three videos
explaining what each option is,
and the pros and cons to each of them.
Let's jump on in and take a look
at the easiest and simplest option, the battery isolator,
also referred to as the smart battery isolator.
The most common type of isolator
is a voltage sensitive solenoid,
like this one here from REDARC, the SBI12.
On the front of this REDARC isolator,
you can see these two connections.
When we install the isolator,
we connect your starting battery to this connection,
and your auxiliary battery to the other.
The isolator monitors the voltage
of the starting battery.
When the isolator sees your car is turned on,
and the alternator is charging,
via an increase in voltage,
the isolator connects the two batteries together,
thus allowing your auxiliary battery
to charge off the alternator.
When you turn the car off, the isolator
continues to monitor the voltage of the batteries,
and when they reach a certain level,
it will separate the two batteries from each other.
This is how it gets its name,
as it is isolating the starting battery,
which means you can power accessories like your fridge
from your auxiliary battery,
and they will not draw power from the starting battery.
This ensures your starting battery
will always have enough life to start the car.
If you accidentally leave the lights on in the car
or radio on overnight, and manage to drain
your starting battery, you can bridge the connection
between the two batteries, and use the powers
of both the starting and auxiliary batteries
to start the vehicle.
This SBI12 from REDARC comes standard
with this blue wire here,
which allows us to install a switch on your dash
to jumpstart the car off the auxiliary battery
if you need to.
If you don't want to use the jumpstart feature,
we would generally use a fuse between the isolator
and the starting battery to protect the system.
The battery isolator can be mounted anywhere in the vehicle,
preferably but not necessarily in a dry area.
We usually mount them under the bonnet
near the starting battery.
In newer vehicles that have a computer-controlled
alternator, using a battery isolator
will not work effectively,
as the car has a charging algorithm
that is more concerned about fuel consumption and emissions,
so will regularly drop the charging voltage
below the cut-off voltage of the isolator.
Basically, the isolator will think the car is turned off
when it's not, and will separate the two batteries,
and the auxiliary battery won't charge.
If you have a car with a computer-controlled alternator,
you will need to look at installing a DC to DC charger,
or more commonly known by REDARC as a BCDC.
If powering a fridge and a couple of small accessories,
you will generally get about two days of power
out of an auxiliary battery.
One downside to the battery isolator
is that it will only charge your auxiliary battery
when the vehicle is turned on,
and will need to run your car for approximately a day
to charge the battery to full.
Another downside is your car alternator
is designed to charge a starting battery,
which is generally a lead acid or calcium battery.
Most auxiliary batteries are AGM batteries
that require multistage charging.
The alternator will charge the auxiliary AGM battery,
but only to roughly 80%.
What that means, if you have 100 amp-hour battery,
the alternator and battery isolator option
will only charge the battery to roughly 80%,
giving you 80 amp-hours, not the full 100 amp-hours
that you purchased.
So that's a bit of a rundown on smart battery isolators
using the REDARC SBI12 as an example.
There are plenty of other brands out there on the market,
and we do stuck a full range in our showroom and online.
If you're looking at installing a dual battery system,
check out the next two videos in the series
explaining the DC to DC charger,
and battery management system.
If you do have any further questions,
please comment below, send us an email
to info@amae.net.au, or call 1300-227-353.