RV FEATURE
ADD IT UP
If you added up the amount of current draw of
all your 12V appliances over 24 hours, the
final figure might look scary. Fortunately, we
don’t run our appliances continuously.
If you have a compressor or 12V fridge, it is
necessary to have it switched on all the time
and most compressor fridges are rated at
around 6A. Fortunately, the compressor
doesn’t run all the time, even though it is
switched on.
The compressor turns on and off to maintain
an average temperature controlled by a
thermostat. So while the compressor draws
6A, it may only actually operate for 30
minutes during each hour. This is called a duty
cycle and most compressor fridges will be
rated in the average amp hours they can be
expected to operate in average conditions.
Don’t be fooled into thinking this is a constant
that can be relied upon. In hot weather, the
fridge will have to work harder to keep the
same internal temperature, so the actual duty
cycle may increase to higher levels than
specified. Further, as a fridge gets older, the
compressor components wear out, meaning it
has to work harder to maintain the set
temperature, increasing the duty cycle and
power consumption.
Does the inside of your van look like this?
It all starts with good quality batteries.
WHAT ABOUT INVERTERS?
Not every device runs off 12V. Mobile phone
and laptop chargers, microwaves, coffee
machines, food processors, CPAP machines
and so on, usually run from 240V mains power.
This inverter shows how many amps it's
drawing while powering 240V appliances.
Many owners fit an inverter to their RV, which
effectively turns 12V into 240V, but doing so
takes a lot of 12V current. A device that is rated
at 300W at 240 volts running from an inverter
will end up drawing 30A from a 12V battery.
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