[Soekris] long-run DC UPS

[Mark Phillips]

Surely it's a simple matter of mathematics and then you'll end up with
the size you want?

For example; if the device draws 10 watts an hour then a standard 650va
ups would last 6.5 hours. So it follows that a 3Kva ups would last 30
hours.

What we haven't allowed for is the UPS' own current requirements. I
would make a stab at 3Kva lasting about 24+ hours with a 10W load on it.
You might get longer with a different type of UPS.

For example, you could build a charger/battery solution whereby a
charger keeps a car/sealed lead acid/gel cell charged and in turn the
5501 is connected to the battery. When the volts die the battery takes
over and runs for as long as it runs for based on it's size.

If you follow the P=IV rule should be good. A standard 75amp car battery
should last you about 100 hours with a 10W draw.

 

On Mon, 2007-08-13 at 19:38 -0400, Adam Jacob Muller wrote:
> Anyone have any experience with any off-the-shelf of home-built long- 
> run DC (I assume we don't want AC->DC->AC->DC here for long-run) UPS  
> system.
> 
> I'm looking for something that can run a simple 5501 (no HD or  
> anything hugely power-consuming -- perhaps an extra ethernet card),  
> but, I am looking for run time in the range of 24-48 hours.
> This is obviously far beyond what any conventional AC ups can  
> provide. Anyone know of such a beast?
> 
> 
> -Adam
> 
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-- 



Mark Phillips, G7LTT/KC2ENI
Randolph, NJ