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Stupot
11-03-2005, 11:33 AM
:help: I'm an old phart who had to stop working when my MSDos laptop was king. I bought an old pc a few years ago and introduced myself to the internet. I've now got an IBM with 40GB, 256MB, CD writer, DVD player, an ordinary 17" monitor and a little HP printer.

My power supply is a reasonably robust solar setup with a 650 watt inverter. everything seems fine in summer but I dunno how it'll go in winter. Could someone please tell me how much power my system is using (a) at startup and (b) at normal running?

Many thanks,
Stupot

godfather
11-03-2005, 11:51 AM
Probably little difference between start-up and normal running.

The specified wattage of the monitor will be reasonable accurate and should be clearly displayed on the label on the back. Assuming it is a CRT type, this will be a significant contributor to the power consumption.

Without knowing the exact PC specs (CPU type and speed etc) I would estimate a running wattage of around 150 - 200 watts plus the monitor.

A new LCD monitor would likely give a significant saving in power.

How many watts of PV do you have installed?

Stupot
11-03-2005, 02:12 PM
:thumbs: Thank you Godfather. If it's likely to be less than 400 watts I think I'll be okay. I've got 200watts worth of panels and only use power for lights, radio and computer. Batteries are 160 Ah.

Thanks again,

Stupot

Graham L
11-03-2005, 03:25 PM
If the desktop takes a total of 230 watts, you'll be pulling 20 amps from your battery. If you could find a reasonable laptop cheaply (you don't need to have a good battery on it --- you've got batteries ;) ) you will cut that to a less than 3 amps. You can buy a kitset DC-DC inverter from Jaycar which would run it without going through your main inverter, or a ready-built one for about twice the price.

Is your 200 watts "label" watts or usable watts? Most manufacturers make panels with maximum output power at over 17 volts, which simple solar battery chargers can't use. So an 80W panel gives about 50 or 60 watts. :(

Stupot
12-03-2005, 09:33 AM
Godfather and GrahamL - :confused: Thanks for your help but these fancy machines seem designed to confuse the already bewildered. My whole setup seems to deliver what I need but the sticker I found underneath the box where the Genie lives says "200-240V - 3.0A" .

If the computer uses 3.0 Amps and the monitor another one then doesn't that mean I need 920 watts to run the thing. I don't understand how this is working from a 650 watt inverter.

stupot

godfather
12-03-2005, 10:31 AM
The maximum rating will apply to the lowest voltage at absolute maximum instantaneous draw I suspect. Are you sure it is 200v, as many are actually 100 v - 240 v.
3 amps at 100v is 300 watts input. At 230 its 1.3 amps as an example. Multi voltage power supplies are common.

The computer will be unlikely to use the entire capacity of the power supply (or the PC would likely become unstable) but the maximum permissable input power still needs to be on the label. Ignore it and go by the results you get.

Or build one of these...
http://www.dse.co.nz/cgi-bin/dse.storefront/en/product/K7217
Or buy one of these...
http://www.centameter.co.nz/

Myth
12-03-2005, 11:34 AM
Maximum power is drawn at startup... if the comp survives that easily, you should be sweet

Stupot
12-03-2005, 12:41 PM
Thanks guys. The sticker says "100-127V 6.0A" and "200-240v 3.0A" but also says "Made in China". Maybe because of the rising but still low value of the Yuan they are taking a bit of my power over the internet to boost the economy. It all seems to work so I guess I'll just keep doddering along.

Peace,
stupot