Topic: Building a DIY UPS - page 2. (Read 8369 times)

My understanding on capacitors is that disc types (solid state) work with AC

I've got no experience of caps on AC, and would assume usage of them is freakishly complicated, seeing AC is a sinewave and a capacitor is meant to smooth out voltage fluctuation ...

The question really is then -> how big are the caps on high quality seasonic (and derivative) PSUs ... Some server PSUs have so huge capacitors they can take 5+ seconds of power outage without the system crashing ... Tho last PSU like that i've had the pleasure to use was built for 386 era server ... (The case+PSU alone weighted over 30kg ...)
most likely not big enough to sustain that kind of loads for the period it takes SPDTs to change and inverters to "gear up" for the output.

You can put caps on AC, but it is much more difficult to properly implement without them blowing up and stuff. They would be there to provide a way of transitioning between inverters, or from AC to inverter without causing massive brownouts and spikes.

Oh yeah, the reason to add capacitors is just to smooth spikes out, batteries aren't exactly good at handling big current spikes.

The real question is how to handle transition from network power to inverters in case of power failure. That's the only thing i need to really solve still, rest is up for building and testing, see how well it works, or how poorly it works

for AC you can't exactly add capacitors so SPDT relays might not come into question...

And they are here 12V not 24V. Using capacitor for just 12V is not a problem at all btw.
You can always utilize one for lower voltage than it's rating is for, and it does not change the capacitance.

Yeah that was my first thought from my younger years and car stereo (what a waste of money, lolz).  The issue is they are 24V DC.  Not sure how they would fit into your wiring. 

My thinking (and it may be wrong) is you need to do four things

a) buffer the 120V/240V feed from power grid <- cap goes here
b) detect input power drop and disconnect protected loads from mains to battery bank (cap in A will continue to power load until switch occurs)
c) have trickle charge system to have battery bank loaded at all times
d) have sufficient inverter capacity to convert DC to AC to power protected gear.

For part D I am thinking a small solar power inverter is likely ideal.  Right?  DC in -> 120V/240V AC out.  Can wire it right into a sub panel and connect it to a bank of protected circuits.

Well they make UPS capable of sustaining entire datacenters during power outages.  If you got enough $$$ you can get just about anything.

http://www.apc.com/products/resource/include/techspec_index.cfm?base_sku=SYA16K16PXR&total_watts=10000

That seems to be a lot of 1000 or more.
I was more thinking like couple of these lil' puppies: http://www.sonicelectronix.com/item_21166_Power-Acoustik-PC1.5F.html

WOW that is cheap, was more like expecting 100€ a piece, just result on google

Capacitor?  Big ones? Lots of them?

The bad news is one capable of providing the necessary current during the transition are likely very very expensive.

220V, 220uF $900+    More like $1 (I can't read).

http://search.digikey.com/us/en/products/SLP221M220A1P3/SLP221M220A1P3-ND/1882197

Single car battery is able to supply 720W for an hour, in theory. In practice more like 600W before voltage drops too low and due to the age of the battery.
5 for full 16A 230V circuit for an hour.

In other words, that single battery is sufficient for a single 4x7970 rig @ ~2Ghash... Or 1 hour for 10Ghash. Most power outages are solved within that time.

Plus the batteries are free

I'd like to see a UPS capable of sustaining a serious mining farm during a blackout. It would have like 50 car batteries lol :p. Imagine an electrical fire or some other mishap then! rofl

The easy part is getting batteries stacked, wired, charged.
Still easy is to power up 12V devices from that: I was thinking a zener diode, regulator, capacitor between battery back and 12V DC sources, so trickle charges can continue normal operation like no load was attached while beyond the regulator etc. is a 12V PSU with 12V devices. and when network electricity goes the trickle charger, 12V PSUs shutdown and 12V devices get powered from the battery pack with regulator +capacitor "cleaned" source.
Some kind surge protector + fuses might be still good idea tho.

The problem arises on how to switch between inverters and network electricity on 230V equipment?
How to "join" together multiple cheap inverters for single source of 230V instead of calculating how much to put behind each single inverter?
I've heard of switches sold for this usage for rack mounting, but i simply cannot find those "STS switches" for sale. Or would SPDT relays switch fast enough when outage occurs? Doesn't that cause spikes, and need something to smooth out the transition?

One problem tho remains at this location is how to clean the network electricity, as it's a bit flaky there, short sub second outages are known to happen there during storms and fuses to blow with no apparent reason occasionally. Network -> converter -> battery back -> inverter -> miners is just not a feasible option due to losses.