Enewsletter
#95 - 31st March 2006
Index:
1) Courses
2) Selectronic
350W - 24V Sine Wave Inverter
3) Prices
4) Feature
Article: Fridges
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1) Courses
The next
Designers course run by Peter Pedals is scheduled
for 8-12th June. The next Weekend course for homeowners
will be given by Karlin on 27th & 28th May. For
more information follow the link to our web site
below: http://www.rpc.com.au/education/courses.html _____________________________________________________________
2) Selectronic
350W - 24V Sine Wave Inverter
This model
has been discontinued by the manufacturer. We have
a few left in stock on sale for $833 ($100 off the
Retail Price!). This is a great little sine wave
inverter for those of you on a small 24V system.
It will do 450W for half an hour and 1000W surge.
Ideal for your TV, computer, blender and small tools.
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3) Prices
Rising copper
and lead prices are forcing up the price of cable
and batteries fairly regularly. Our Australian Dollar
has fallen by about 10% against the US Dollar in
the past month or two, which has forced up the price
of some imported products including the Sundaya range.
However, this range is still great value for money.
Their 12 volt lighting products have proven to be
the most reliable that we´ve ever sold (see
them in our Solar Kit section).
Australian
customers can view our Price List here:
http://www.rpc.com.au/pricelists/pricelists-download.html
Overseas
customers wanting a Price List should email our office
with their contact details. ______________________________________________________________
4) Fridges
This month´s
feature article is about the 73l eutectic fridge
and a number of tests we´ve been running with
it.
Power Consumption
of a 73 Litre Eutectic Fridge or Freezer
Eutectic
refrigeration is often used in fishing vessels. A
eutectic fridge has a `cold sink´ of very cold
fluid to help it to maintain its cold temperature
once power to run the fridge compressor is switched
off or unavailable. The basic principle is that when
the engine of your boat or vehicle is running (and
therefore generating power), you run your fridge
so that the eutectic fluid goes below 0°C. This
then keeps your fridge cold for a further 24-48 hours
(while your engine is off). The 73 litre eutectic
fridge- freezer that we sell has this fluid inside
the walls where one would expect to find normal fridge
insulation.
Another
application is for camping and touring. If you drive
your vehicle for at least 4-5 hours every 2 days,
you can use your fridge without any solar or other
charging source.
The advantage
of a eutectic fridge in a solar set-up is that you
can time the fridge to come on in day light hours
only (when your solar panels are generating power).
This lowers the system voltage a bit and helps to
get a bit more amperage from your panels. More importantly,
it helps reduce the battery inefficiency that results
from storing power in your batteries during the day
to run the fridge at night! And the last bonus is
that because the fridge does not need power to stay
cold for 1-2 days you may be able to use a smaller
battery bank!
One of our
staff ran and monitored his eutectic fridge power
consumption for a whole year in the Nimbin area.
This is a sub- tropical area of Australia with summer
day temperatures around 32C and winter around 20C.
The monthly
averages were:
73 Litre
Eutectic Auto Fridge Power Consumption - A/hr @ 12V
AUG...
11.1
SEP... 13.7
OCT... 14.8
NOV... 15.5
DEC... 18.4
JAN... 19.3
FEB... 19.9
MAR... 18.2
APR... 12.5
MAY... 12.2
JUN... 8.29
JULY... 9.82
In our shop
in Nimbin, we ran 4 tests to establish how much power
the eutectic fridge uses in different situations.
1) The
first test was conducted by bringing 4 litres of
water at room temperature 23 C down to 3 C. The cold
water was replaced with another room temperature
4-litre bottle of water daily. The power consumption
was then measured with a data logger, and the battery
voltage was regulated at 12.8 volts throughout the
test. The average number of amp hours required daily
by the eutectic fridge was only 13.2 Ah.
2) Considered
by many to be a very small load, the 4 litres of
water was replaced with a carton of beer (24 bottles
each 375 ml). The amount of energy required to bring
the beer to 3 C from an ambient temperature of 23
C was then logged. The beer was then left in the
eutectic fridge for the remaining 3 days of the test
to establish how much energy was required to keep
it at this temperature. The average daily power consumption
was only 12 Ah.
3) As the
eutectic fridge can be used as a freezer, the third
test required the freezing of 10 litres of water.
Ten 1-litre bottles of water were added with a starting
temperature of 23 degrees. The eutectic fridge took
around 12 hours to bring the water to freezing point.
A total of 96 Ah was used over the first day to bring
the ten bottles down to -9C. To hold the ice at this
temperature used less power over the next 3 days;
80, 65 and finally 43 Ah were required over the next
three days.
4) The final
test was to measure the eutectic fridge´s ability
to maintain a safe cold temperature after being disconnected
from the power supply and allowed to act as an "esky".
The gradual rise in temperature was monitored for
a further 3 days. Due to the eutectic layer, the
eutectic fridge took 3 days to rise above 10C.
This performance
makes the eutectic fridge appropriate for freezing
and transporting goods such as fish in areas where
power supply is limited or intermittent from a vehicle
engine or other power supply.
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That´s
all for this month folks! Your comments and questions
are most welcome; however, there is no need to send
our newsletter back to us when you reply! If you
would like price or product information, please tell
us which country you are from if it is not evident
from your e-mail address. This allows us to assess
if local GST (tax) is applicable or whether 240 Volt
50HZ products will work in your country etc.
If you wish
to change your email address or unsubscribe to the
newsletter please follow the link below to our web
site: http://www.rpc.com.au/news/subscribe.html
Dave Lambert
and the RPC crew
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