DIY UPS - Help / suggestions please!

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chrisjunkie

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Topic # 30284 3-Feb-2009 19:08

Ok so after the power outage today, I realised that if I'm not around to bring the FW and web/dns server back up my family is stuffed for internet access.

I was thinking about getting a UPS but then I thought about other options as I am looking at running around 3-4 computers and a modem for close to 5 hours.

After some research I have found multiple resources that suggest using a car battery charger / power supply into a battery then into an inverter. This has flaws:

Dual conversion (power loss) and the car battery wont be any where near enough for 5 devices.

I thought I'd take a different approach:

Battery Charger (high amperage) 12 or 24V battery then 12 or 24v psu (often used in car pc's and I have found models that can output 200-300w)

What I'm stuck for ideas on is what I can use for a cheap, simple battery charger? Idealy it will output 20amps.

Any ideas guys? I know this is the best place to ask

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Reply # 193769 3-Feb-2009 19:32

its a nice idea, but chances are it will be illegal to connect a self made product onto the mains.

Also personly I would never connect a self made power object to my $3000 computer.

chrisjunkie

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Reply # 193771 3-Feb-2009 19:34

$20 dollar computer(s)

I call them servers but all they are is 1.8ghz 512mb - 1 gb ram and a 40gb hdd.

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Reply # 193788 3-Feb-2009 20:09

Whatever you crearte I doubt you will get five hours power for three PCs. I have two Belkin 1.2KvA here powering three PCs, router, cable modem and five external HDD and the time is about 30 minutes.

Get one or two of these, install the software and plug it to your main PC. The software will automatically shutdown the machine if the battery level goes too low. You can manually shutdown the others.

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Reply # 193794 3-Feb-2009 20:38

chrisjunkie: Ok so after the power outage today, I realised that if I'm not around to bring the FW and web/dns server back up my family is stuffed for internet access

do they not start up automatically? perhaps you're using the wrong software?

if you really cant avoid some manual intervention then surely a static ip or dynamic dns configured in internet router plus remote access ssh/rdp/vnc should give you remote access so you can just connect in and fix stuff.

sure, get a UPS - there are some featureless ones available for next to nothing these days and they will give 5 computers a good 30+ minutes if you dont plug printers/screens etc in to them. to get 5 hours runtime you're looking at a lot more batteries. I get about 1.5 hours from a ups and extended battery conncted to 3 servers at the office, but collectively the ups and additional battery weighs over 80kg! Check the APC chart for extended runtimes here: http://www.apcc.com/products/runtime_for_extendedruntime.cfm?upsfamily=164 To get 5 hours runtime at full load I would need 5 additional batteries to go with my main unit, or 3 additional batteries at half load! (each of these batteries weighs in at almost 60KG) I'm not sure how may car batteries it would take to achieve the same.

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sbiddle

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Reply # 193795 3-Feb-2009 20:38

You will get nowhere near 5 hours runtime. Doing some quick maths and making some big assumptions I've give you around 30 maybe 40 mins tops running 3 PC's off a standard car battery.

Remember that it doesn't matter the size of the battery - it's the capacity. A big car battery doesn't necessarily have any more capacity than a smaller gel cell, it just has a far higher CCA (cold cranking amps) to sustain the extremely high loads from a car starter motor.

Filterer

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Reply # 193802 3-Feb-2009 20:46

How about just changing the bios settting to get it to reboot after power failure - almost all computers have this setting....

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chrisjunkie

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Reply # 193806 3-Feb-2009 21:02

Ok maybe 5 hours was a bit much to ask for. I am thinking for in the future when we go voip. Worst thing during a power cut is not having any power.

They did start up automatically but halted on keyboard and I cant for the life of me find the setting in the BIOS. Would be nice to have them cleanly shut down too so maybe I just go for a standard UPS?

I would most likely also have to create a script that logs in to the servers and shuts them down all with a little power to save...

Would be nice to keep pfsense and my modem going so that pfsense can wake up my other servers?

Help?

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Reply # 193829 3-Feb-2009 22:07

chrisjunkie: Ok maybe 5 hours was a bit much to ask for. I am thinking for in the future when we go voip. Worst thing during a power cut is not having any power.

They did start up automatically but halted on keyboard and I cant for the life of me find the setting in the BIOS. Would be nice to have them cleanly shut down too so maybe I just go for a standard UPS?

I would most likely also have to create a script that logs in to the servers and shuts them down all with a little power to save...

Would be nice to keep pfsense and my modem going so that pfsense can wake up my other servers?

Help?

Look for the "halt on" errors settings in the bios. I've not seen a motherboard that didnt have a comparable setting yet. Try here for reference: http://www.pcguide.com/ref/kb/swBIOS-c.html

As for the auto shutdown stuff - if you get a APC UPS then windows recognises it as a battery and enables "suspend" which is faster than a full shutdown. If you get other brand UPS's you might only get aut shutdown with the extra software they ship with which is not so convienent.

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chrisjunkie

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Reply # 193949 4-Feb-2009 12:07

I found a UPS with 800VA capacity. What I can do then is have a script running on one of my servers that shuts down the others while staying up so that when the power does come back on it can WOL the machines.

Good idea?

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Reply # 193951 4-Feb-2009 12:18

chrisjunkie: I found a UPS with 800VA capacity. What I can do then is have a script running on one of my servers that shuts down the others while staying up so that when the power does come back on it can WOL the machines.

Good idea?

The Belkin UPS comes with a client/server software - the server will send a signal to all clients to shutdown then will power down the server...

The problem on your plan is that you want your server to stay up. This is ok for ten minutes outages, but anything more than that you risk your server crashing when the UPS run out of power.

A UPS is not there to keep your infrastructure running. It's there to ensure your computers can have a safe shutdown. To keep things running a longer time you need generators...

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Reply # 193952 4-Feb-2009 12:18

800VA is very small if you're running 3 PC's and depending on the brand may struggle to cold start 3 machines.

chrisjunkie

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Reply # 194090 4-Feb-2009 19:06

Ok all,

This is dragging on slightly for some of you and sorry about that but I am trying to reach the best possible solution.

A 1500VA UPS should be fine for my 3 servers? Then what if I get one or two truck batteries and hook them up (in parallel or series depending on UPS) so that I can extend my time?

Currently it looks like UPS's only have 2 7AH batteries in them but what about two 150AH truck batteries?

Help appreciated!

tonyhughes

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Reply # 194101 4-Feb-2009 20:09

chrisjunkie: what about two 150AH truck batteries?

Help appreciated!

You are trying to transport urine up a rise in the mountains using a multi-pronged garden implement designed for the relocation of fallen leaf matter in a garden by sticking with the vehicle battery idea.

Use UPSs. Decent UPSs can be had for the same price as decent vehicle batteries, and of course you still need to charge, regulate, monitor, invert, maintain the vehicle batteries. You will get WAY less reliability, WAY less safety (non sealed batteries? No thanks!), and WAY more cost.

So my question to you:

WHY would you not get a UPS (or a few)?

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chrisjunkie

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Reply # 194104 4-Feb-2009 20:16

Tony:

I plan on getting a UPS and upgrading the batteries to truck batteries then I have a longer run time

sleemanj

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Reply # 195210 10-Feb-2009 21:57

I have one word for you.... generator.

Seriously, petrol generators really are quite cheap (relatively) and they'll run for days if need be.

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