[Beowulf] power usage, Intel 5160 vs. AMD 2216

Joel Jaeggli joelja at bogus.com
Fri Jul 13 18:09:13 EDT 2007


Jim Lux wrote:
> At 07:31 AM 7/13/2007, Robert G. Brown wrote:
> 
> 
>> For small/personal clusters I change my mind again.  I tend to buy cheap
>> UPS's for my house because our power bobbles for 1-5 seconds nearly
>> every heavy rain/windstorm we have, which is why I know from direct
>> experience that the batteries in these UPSs are lucky to last two whole
>> years.  I've got something like three of them where I'm plugged into the
>> surge side because the UPS side is dead (no power at all) or goes down
>> anyway when power bobbles, to the tune of system crash AND the maddening
>> beeping.  I'd love to find a 10 second PDU/conditioner that used a
>> really large capacitor instead of a battery to buffer short outages,

Ten second non-chemical energy storage would be a good candidate for a
flywheel.

> 
> 
> Tough.. the energy density of lead acid is really high.
> 
> Here's an example using one of those big 1 Farad 12V caps the auto sound
> people use.. say the UPS can take voltage drop of 2V on the "battery". 
> At 12V it stores 72 Joules. At 10V, you've recovered 22J. That's about
> 1/10th second, assuming the UPS is 100% efficient, which it isn't.
> 
> 
> For 10 seconds, you need 100 Farad.. that's a BIG cap.
> 
> 
> The battery life *should* be a whole lot longer (Lead Acid batteries can
> have 10-20 year lives, as can NiCd), however, the run of the mill UPS
> doesn't treat the battery very well.
> 
> 
>> especially at mass market prices.
> 
> That's the problem.. mass market means race to the bottom for quality
> and life, to reduce initial price.  You can get a PC UPS which provides
> 10 minutes or so at 200-300VA for $50-70 at the local big box store.  If
> you were willing to pay, say, $300-400, you could probably get 20 year
> life.
> 
> (you could cobble one together cheaper.. a high quality charger is
> probably $50-100, good quality battery is around $20, a high quality
> inverter is $200 or so, and then you'd need some sort of transfer switch.
> 
> 
> Take a look at products aimed at the sailboat/solar power market, which
> are definitely aimed at longevity.
> 
>> Does anybody know of such a beast?  No battery, no toxins, just a big
>> cap and small price?
>>
>>    rgb
>>
>> -- 
>> Robert G. Brown                        http://www.phy.duke.edu/~rgb/
>> Duke University Dept. of Physics, Box 90305
>> Durham, N.C. 27708-0305
>> Phone: 1-919-660-2567  Fax: 919-660-2525     email:rgb at phy.duke.edu
>>
>>
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> 
> James Lux, P.E.
> Spacecraft Radio Frequency Subsystems Group
> Flight Communications Systems Section
> Jet Propulsion Laboratory, Mail Stop 161-213
> 4800 Oak Grove Drive
> Pasadena CA 91109
> tel: (818)354-2075
> fax: (818)393-6875
> 
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