Newsletter Archive

E-News Issue #65

6 November 2003

Low Wattage Appliances

I often get requests for 'lower than usual' wattage appliances for customers who have the available power but whose inverter is of a modest size. This particularly applies to kettles, irons, and hair dryers. Most of the standard ones are often around 2000 watts. They are designed to do the job quickly in our modern, fast society. However, low wattage units will often do the job, perhaps at a bit slower pace.

Most electrical jugs are 2200 watts but there is a nice Kambrook kettle (KE9) that holds a litre and is rated at 1250 watts.

Lately, I’ve had requests to source low wattage irons and hair dryers. These are sometimes sold as travel items (e.g. to take on holidays). If you have any suggestions in this regard, let me know and I’ll pass on your suggestions.

LCD Television

Bob got one of these new style televisions – his LG model uses 3.8 Amps – a bit more than he expected - when connected directly to a 12 volt battery bank. A 'normal' 14 inch / 34 cm television usually uses around 5 amps on the DC side of the inverter. Bob has heard that the Sharp one is better quality, but they wanted $140 for the DC lead!!!

LCD Computer Monitor

My computer is an AMD 1300 Mhz with 128Mb RAM, 20 Gig ATA 100 hard drive, CD burner, and 56K built in modem with a 15-inch LCD monitor.

I measured the wattage with an Emu meter at 101 Watts and 105.4 Watts on a Spar meter on the AC side with everything on. Taking a bit of an average gives 103 Watts of which 19 Watts is consumed by the LCD monitor.

On the DC side of my Selectronic SE22 inverter, the current was measured at 5.0 Amps @ 25.4 Volts (about 127 Watts), which gives an efficiency of about 81% (when nothing else is being run off the 1600W inverter).

Interestingly, turning the monitor off made no difference to the power consumption as measured on the DC side. I assume this is because the inverter became more efficient with the extra load. If the computer system is run with an 800W resistive load also on the inverter, the computer system still use 5 amps @ 25.4 volts with everything on, but this reduced to 4.0 amps when the LCD monitor is turned off.

Forgetting this anomaly, I would say that using an LCD monitor over an older conventional one saves about 50 Watts. In a grid connected ‘office’ situation – 8 hours/day, 250 days a year, the saving in power would be in the order of 50 x 8 x 250 = 100kWh. In a solar situation, with your computer on 8 hours per day, you should save about 400Wh per day, which would be a saving of about one 120 watt panel. This depends of course on your solar insolation, seasonal variations etc.

ISDN Modems

In Australia there is a Telstra Service for Internet users called ISDN. In brief, this service gives you a second phone line and a 128K-speed modem (64K when the phone is being used). Telstra supplies the 'modem' device. The service offers Internet speeds 2-3 times faster than a normal 56K modem dial-up service. It is available in many areas where ADSL is not available.

Now that the ad is done, the electrical requirements are easy and straightforward. It uses 2.7 Watts measured on the AC side. You can turn it on only when your computer is on so, compared with the computer; the power usage of this special modem is pretty insignificant.

We welcome your comments, questions and price inquiries about this e-newsletter. We would appreciate it if you could tell is which country you are from (if this is not obvious from your email address). You do not need to return our whole newsletter back to us with your email.

Cheers from Dave and all the RPC crew.

Dave Lambert (Director)

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We install solar systems in Northern NSW and Southern QLD.


QLD:
Gold Coast (from Coolangatta to Southport), Nerang and Hinterland (Beaudesert) and out West (Warwick, Stanthorpe, Killarney)


NSW:
Northern NSW (Tweed Heads to Yamba, including Evans Head, Byron Bay and Ballina); the Far North Coast Hinterland (Grafton via Lismore to Murwillumbah) and out West (Casino to Tenterfield, including Drake and Tabulam, as well as Woodenbong and Bonalbo)

For larger system we also go up to Brisbane or down to Coffs Harbour and even Glen Innes. Other places by arrangement.