RV FEATURE
However you travel, it’s important to
understand your van’s 12V system in order
to avoid flat batteries and the associated
angry kids (or spouse), and fridge full of
warm beer.
The problem starts with our technologycentric
lifestyle and dependence on modern
conveniences. Television, lighting, DVD
players, mobile phones, tablets, modems,
heaters… they all use power and a surprisingly
large amount of it.
FIRST PRINCIPALS
Think about your 12V system like an irrigation
system for your garden. Your batteries are like
water tanks, with your solar panels working
like your roof and gutters to collect rain water
and pipe it into the tanks.
Your electrical appliances are like sprinklers.
The bigger the sprinkler, the more water it takes
from the tank. Small sprinklers use a small
amount of water but a lot of small sprinklers
running at the same time can use as much
water, if not more, than a single large sprinkler.
It is the same with the 12V appliances in your
RV. Some, like LED lights, use small amounts
of power. Some, like water pumps and stereo
systems, use a lot of power. Run a few lights
and a TV for a few hours a day and they will
use a surprisingly large amount of your
battery’s reserves.
A typical power system in a modern caravan.
SO HOW DO WE
MEASURE THIS?
Think back to the irrigation system. The water
tank’s capacity is measured in litres. Let’s say
it holds 100L. If we water our garden from a
single sprinkler, with a flow rate of 1L per
hour, our water tank will be empty after 100
hours of watering the garden.
In much the same way, the flow of electricity
through the wires of our electrical circuits,
called the current, is measured in amps. A
battery’s capacity is measured in amp hours.
If we have a single LED light that draws 1A, it
will consume one amp every hour (referred to
as 1Ah per hour). Left to shine continuously,
that light will run the battery completely flat in
100 hours.
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