DSM-G600, DNS-3xx and NSA-220 Hack Forum

I don't think that is possible neither would recommend this. Power failures often don't come alone. immediate switch on after the power is restore could damage the unit because of the voltage fluctuations.

What about just plugging it into a UPS... the prices have come way down and if you are just powering your DNS-323 (which uses much less than a computer and monitor) it should last quite a long time... You didn't specify how long the power cuts are, but you should look into it.

I have a cheap $80 UPS powering my DNS-323, router and a couple of NSLU2s and it's gone over an hour without mains power.

Last edited by ambanmba (2008-03-19 13:57:47)

Hi Potgieterd,

potgieterdl wrote:

what va is it? the power cuts are about 3-4 hours long.

Have you considered powering direct from the 12V battery in the UPS?  I reckon 28 or 33AH battery would cover you for that time.  All you need is suitable regulator for 12V and 5V inputs to DNS-323.

Jaya

Hi potgieterdl,

potgieterdl wrote:

that was the route i wanted to go, but the problem is that i need an inverter to charge and convert the current. They are a bit expensive. But in the end i`ll have to go that route i suppose.

One way is to use the battery in the UPS itself provided charging circuit is can give the amps needed.  Then simple 12V and 5V regulators would  be sufficient to feed the DNS-323.

Jaya

That's making the assumption you are using a starting lead acid battery.  A good deep cycle battery will allow you to discharge 50% for at least a good 5000 cycles.  That's over 10 years doing it every day.  We use these types of battereies for large UPS systems and solar facilities where there are no utilities. 

If you have the shut down part taken care of, you could also build a relatively simple circuit that starts a timer when the power comes back on, then momentarily closes a relay after a designated amount of time (to allow voltage and frequency to stabilize).  If you connect the relay in parallel accros the power button on the unit, Voila, instant start up.  (You may want to go solid state as apposed to a mechanical relay.)  It's the equivelent of somebody pushing the button.  You may want to go solid state as opposed to a mechanical relay.

Of course, this will most certainly void out your warranty, as you will have to do a little soldering.

Last edited by bq041 (2008-03-19 17:00:13)

Depends on how much you want to spend and your available space / location, but is solar an option?

Another option is a cheap generator like this one: http://www.gmcompany.com.au/index.cfm?m … mp;pid=644
These things cost about AU$100.

potgieterdl

How long a UPS will last is dependent on the manufacturer - get the manual, there's usually a chart or table with some figures.  I'd love to tell you that it's a straight forward task but it's not - some UPS are designed to run 10~20 minutes at full load, others more, others less - I've seen one very popular unit (18kVA capacity) with a full load run time of 3-1/2 minutes - and it's not a linear calculation either - half load on that unit would not have been 7 minutes, but closer to 10.

Forget about the UPS, especially the smaller ones, they are not designed for extended run - find yourself an outdoor store and get yourself an inverter, a deep cycle battery and a charger - back in the '80's, I used TrippLite, but there are much more efficent units now from manufacturers such as Xantrex and Vector - Black & Decker are quite popular, and are relabelled Vector.  Avoid the stuff that plugs into the cigarette lighter outlet.

100W at 12V is 8~9A, outages average 4 hours, that's a 32~36 AH requirement - I would not go smaller than 80AH on the battery, and a 6A charger should handle the recharge side of it.

I use a double pole, double throw relay as a "changeover" to switch the "critical" load from inverter to utility, with a time delay relay feeding the coil on the changeover relay - this is very important - it prevents the changeover relay from transferring for the first 2~3 minutes after power is restored - these last two should be available at any good refrigeration place.

fordem wrote:

I've seen one very popular unit (18kVA capacity) with a full load run time of 3-1/2 minutes

18kVA? That's more power than my entire house draws.  I think you mean 1.8kVA (1800 VA)

potgieterdl

Fordem is right, you my just want to build your own.  A good deep cycle battery and 140-200 watt inverter will get you going.  Inexpensive battery chargers should also be easy to find.  The other option which I have done several times, is try to find an old UPS that somebody wants to get rid of because of a dead battey.  Then just hook it up to an external deep cycle battery of appropriate size.

fordem wrote:

Sorry bro - that was not a typo - that's 18 kVA as in 18, 000 Volt Amperes...
...The stuff I work on ranges from about 6~160 kVA - but mostly in the 20~40 range.

Worked with ones around 15kVA, also.  Sorry about that, but my assumption on the size was based on the context of what the discussion was -- running a dns-323 on one.  When talking about 100W to somebody on a budget, 18kVA isn't exactlly my first thought when I hear "popular UPS."

Yes - this works but - it's also been known to be problematic in the long term - when I said the units were not designed to run for extended periods, it's not just the batteries, it's also cooling.

I agree with you, if it is being run at a high load.  However, running 100W or less on a unit designed for 1000VA should not yield a cooling issue -- at least I have not run into it and have been doing it for several years.  The big advantage is cost (I picked up a couple for free), so I really don't mind if one eventually goes out.

Now, I did have a 35kVA running our server and simulator building at a college that would only last about 2.5-3 minutes until it overheated; though I could get 4-5 out of it if I started a pedestal fan and blew it at the unit.  Somebody long before my time had the brilliant idea of installing the thing in a basement storeroom...