Feeding Used UPS for backup?

[t19]

Has anyone ever given any thought to using a Lister to feed a used computer Room UPS?  These units are heavy duty, easy to get batteries for, come in sizes of 3 to 20 KVA single phase and could power a house for hours, and they are cheap to pick up... too big for modern computer rooms but no bigger than a fridge.

I thinking of sourcing one to feed batteries to the house needs, after the Lister shuts off for the night, they put out clean sinewaves and have bipasses built in.

[trigzy]

Thought of it - would love it, too bad the UPS and batteries of that size weren't available for cheap/free.  The chargers in those units usually have PF correction, and compensation for fluctuating input voltage.

Steve

[t19]

Yeah thats what I thought.  I use to sell used units, so I'm calling around to some of my old contacts to see what is out there.  Many of the older biger units are being phased out in favour of rack mounted units.

[n2toh]

Yea I thought of it too, but never considered buying a used one. How large is a 20Kva unit with batteries for a day at 25% load?

[t19]

About the size of a good full sized fridge.  Course you can always add battery cabs, which are not too expensive

[hotater]

  My next step at Magic Hot Springs is to put in some kind of battery system and use the Lister for charging.  The UPS seems like it would be perfect, IF, it's designed for constant cycling.  Some are emergency units that do good at holding a charge but not good and recharging day after day.

The part that really messes up off grid living is *start-up* loading.  It does no good at all to have 3K or so available all the time (as I do) if two loads *starting* takes more than 3Kw.  Sooner or later the freezer and the heating pumps try to start at the same time and it shuts down the computer and dims the lights until something trips.

I'm beginning to think it's worth the extra expense to get inverters, charge controllers, and batteries for off grid use.  The better charge controllers will accept anything from 9VDC to 240AC to charge the battery banks and maintain them.  There's remote panels that show condition and charge and available power.  I think I could cut my Lister run time in half by charging batteries with a heavy load on the engine for several hours as opposed to loafing along at a third throttle for many hours.

I've given up hope of ever being able to figure out amp hours, watts, volts, tapered charging, and all the math neccesary to figure out what I *need*.  I'll just get the biggest I can afford and figure out how long it takes to recharge.  What I would HOPE for is enough surge power to total 5Kw and count on running the Lister several hours a day to re-charge batteries.

The outback (inverters) forum is a great place to go to try to learn it, but it somehow escapes me.   
http://www.outbackpower.com/forum/index.php

[cujet]

Something to consider, the auto makers have discovered that NiMH batteries cycle frequently in hybrid cars without problem. At home, the starting loads could be handled by a grid tie inverter powered by a small NiMH battery bank. I am sure it could be done. Once the Taiwan companies gear up to make grid tie inverters, this could probably be done on the cheap.

Chris

[t19]

I remember the batteries liked being excersized, verses waiting in standby mode all the time.  You can also buy cabs with dead batteries and install nice deep cycle types

[n2toh]

I remember the batteries liked being excersized, verses waiting in standby mode all the time.  You can also buy cabs with dead batteries and install nice deep cycle types

T19

I recall when working for an ISP we had an 80KVA 3 phase unit (the make escapes me) that could run with a leg out, can most 3 phase units do this? It could also BOOST the line power in the event of a brownout.

Also from what I recall don't most online units use deep cycle batteries?

hotater

it would seem that an online single phase UPS should do what you want, That is provide power when the roid is off and the startup power you desire.

[Tom]

Just get a Xantrex/Trace SW series inverter. I have a 2512 unit that's rated for a 2500 watt 120V AC continuous output and has inputs for 12VDC 120VAC utility and 120VAC generator. This unit will charge batteries and power the house at the same time. It contains programmable genset start/stop controls and if you manage to exceed the 5000 watt surge rating it will start the genset, synchronize to its frequency and combine both outputs.

I used it with an 6.3 kw Onan LP genset with good success for several years. The trace inverter will even allow you to set the battery charge rate so we can run our Listers and maximum efficiency. These inverters can produce 240VAC by hooking 2 of them together and running out of phase. The utility interconnect allows you to buy or sell power to the utility co and allows you to use the system as a whole house ups. YES they are cool. Oh yea IIRC they have 5 programmable relays.

[trigzy]

Tom,
       I love the phrase "Just get a...."   - they're a real real nice unit - but not by anymeans cheap.
Speaking of that anybody figure out thier cost per kilowatt hour including all startup costs yet?  (Sorry if the numbers depress you.)  Good thing all the fun in tinkering with these makes you forget about the price.

All "proper" UPS batteries are of the deep-cycle type, and all of the ones I have ever seen are sealed.  (Office buildings and workers have this funny thing about not liking Hydrogen gas and the smell of sulphuric acid)

Most large commerical UPS's have very short charge time, in anticipation of another blackout, as well as generator tie in capability, remote monitoring etc etc.  The sad part is, many of them end up sitting in a basement and then get thrown out by some manager who doesn't know what it is.  Others seem to show up a surplus centers for a fraction of thier origional price, but I haven't found any continuous reliable source of them.

Steve

[Clay]

Is anything cheap any more?

I am in the process of setting up the generator to run through an inverter/charge controller into 6 volt golf cart batteries. I did this for a couple of reasons. I can afford these batteries at $50 a piece, they are 6 volt and therefore will be easy to replace in the same configuration with better batteries later, and they can handle being charged and discharged repeatedly.

I just have to buy the inverter now and wire the whole thing up.

[t19]

The Big players when I designed and built computer rooms were Emerson, Liebert, Excide, EPS, Tripp-lite.  THe APC units I have seen are not what I am looking for, too small, not enough battery Square wave outputs. (I hooked up an Osilliscope to one.... I must be one of the last people on earth that know how to run one)

My ideal UPS is a single phase unit, 12 - 18 KVA, (the type IBM gave away with the first AS400's) and I would love it it use a Feroresonant (sp) transformer.  It was a trick used by cheaper UPS that produces a nearly square wave to make a sine wave, and all the associalted harmonics.  The transformer smoothed out the sinewave.  It was cheaper than a multileg SCR setup to produce a true sinewave.  They could also call this an ONLINE unit because the transformer worked like a capacitor and gave the vendor time to turn on the UPS durring a power failure.  It should have 1 hour of battery at 100% load.  I'm only running 2.5 Kva at night so I should have some good ride through.

If not, most allowed for more batteries to be added.  It would also allow for Solar and Wind charging to be applies as well.  Also, most UPS have lots of inputs for controls and alarms.

This means that when running on Listor, it charges batteries and provides power, and if the Listor stops, power continues to the house while I sort out the problem.

[n2toh]

The Big players when I designed and built computer rooms were Emerson, Liebert, Excide, EPS, Tripp-lite.  THe APC units I have seen are not what I am looking for, too small, not enough battery Square wave outputs. (I hooked up an Osilliscope to one.... I must be one of the last people on earth that know how to run one)

My ideal UPS is a single phase unit, 12 - 18 KVA, (the type IBM gave away with the first AS400's) and I would love it it use a Feroresonant (sp) transformer.  It was a trick used by cheaper UPS that produces a nearly square wave to make a sine wave, and all the associalted harmonics.  The transformer smoothed out the sinewave.  It was cheaper than a multileg SCR setup to produce a true sinewave.  They could also call this an ONLINE unit because the transformer worked like a capacitor and gave the vendor time to turn on the UPS durring a power failure.  It should have 1 hour of battery at 100% load.  I'm only running 2.5 Kva at night so I should have some good ride through.

If not, most allowed for more batteries to be added.  It would also allow for Solar and Wind charging to be applies as well.  Also, most UPS have lots of inputs for controls and alarms.

This means that when running on Listor, it charges batteries and provides power, and if the Listor stops, power continues to the house while I sort out the problem.

T19

yea we had a Liebert 36Kva that was the SMALL one . we inherited it from the previous tenant.

on a 10 to 20KVA unit would it not be prudent to adjust the recharge rate of the battery bank so as to avoid overloading the Lister?

[dwkdnvr]

Just get a Xantrex/Trace SW series inverter. I have a 2512 unit that's rated for a 2500 watt 120V AC continuous output and has inputs for 12VDC 120VAC utility and 120VAC generator. This unit will charge batteries and power the house at the same time. It contains programmable genset start/stop controls and if you manage to exceed the 5000 watt surge rating it will start the genset, synchronize to its frequency and combine both outputs.

This is a timely discussion, as I'm in the early stages of planning an off-grid cabin/house with my wife and have lots of quesitons. I was just looking at the SW series yesterday and they seem to be closest to what I need, but I didn't pick up on the ability to combine the AC input with the inverter output to 'double up' the available power.  I had though it was more of a straight transfer switch functionality. I'll have to look again, because if it can to that then I think my choice is much clearer. Update - read through the Xantrex user guide, and it doesn't really emphasize this feature. It seems to be covered on page 90 of the 4025 manual in the 'utility support' section rather than the generator support section, which strikes me as odd since it seems much more valuable with a generator.

The choice between Lister+genset vs Lister +'alternator' +charge controller is one I've been mulling over, since solar+batteries+inverter are a given (big question as to how much solar, though). If the Xantrex can combine outputs, then Lister + genset seems to be ideal, as the inverter will divert/manage power as needed and you don't have to rely on the Lister alone to handle the peak loads.  This makes me much more comfortable with the idea of a 6/1 - I was worried that either a 12/2 would be 'needed' to handle bigger loads like pump startup, or else I'd be looking at a big honkin inverter.

The price tag on the Xantrax SW guys is pertty steep though. It may be worth it if though if it pays back in terms of simplifying the overall system design.