turn old UPS into a Sine Wave Inverter

[simoin]

Does anyone know of/ has heard of projects to turn old computer Uninterpretable Power Supplies into a good quality Sine Wave Inverter? I have got an old UPS with it's former faulty batteries removed and am wondering about hacking out the relevant parts to make it into a cheap Inverter for my Solar panel/Battery System...

If anyone has any idea's on if this can be or has been done let me know. Would be a great (and cheap) way to feed back some power to the grid or just run a few lights...

Ta

 

[Sceadwian]

Depends on the native voltage the UPS used, I'm going to asume most of them use 12 volts (though I could be completly wrong) in which case it would be a trivial task of removing the internal battery and hooking up the power wires to your battery bank. I think it'd be a very workable project.

 

[simoin]

more detail

just to add some more detail, i pulled out 2 batteries from it that were, model number LA12-17, 12Volt, 17Ah/20Ah. So I guess it would be 24 Volt, but that should still not be a problem if I run it off a 24volt battery bank or a 12volt battery bank with some form of voltage doubler.

The UPS is an: APC SU1400INET, they do not have the exact model on there website still as this ups is a bit older but I think this is almost if not exactly the same.
https://www.apc.com/resource/include/techspec_index.cfm?base_sku=SUA1500I

by the by, did i mention that the batteries charge from solar PV panels and that I want to run some lights or whatever from this, I guess that's the normal usage of an inverter, but I don't want to have to hook up mains power to the UPS for it to run start etc.

 

[HiTech]

Check to see if those two batteries were wired in series or parallel. Parallel would provide longer run time of the UPS, which makes sense. As for solar panels as the source, how do you plan to get enough current from those things to run a substantial 120v load? They are low current devices that cost plenty for the ones that can supply a few amps, let alone 15 to 20 amps!

 

[eblc1388]

Check to see if those two batteries were wired in series or parallel. Parallel would provide longer run time of the UPS, which makes sense.

The quoted statement does not make sense.

A 24V inverter design uses half the current that would be needed if it is a 12V design for the same loading so the run time of the UPS is about the same.

It is a bad practice to connect batteries in parallel because one would reach end of discharge faster than the other and then there will be circulating current. Connects in series make sense.

 

[HiTech]

Well go talk to the excellent engineers at Trace engr. who produce the world's best inverter/chargers that operate from banks of 6v & 12v batteries. Somehow they make it work!

You got me curious so I removed the cover to my UPS and sure enough -- two 12v batteries in parallel. There must be a charge monitor circuit in there to assure each one receives equal charge.

 

[Nigel Goodwin]

Well go talk to the excellent engineers at Trace engr. who produce the world's best inverter/chargers that operate from banks of 6v & 12v batteries. Somehow they make it work!

It's not a problem, as long as you use identical batteries, in identical condition, which a UPS will - and you should always replace them as a pair with new identical ones.

 

[Hero999]

Paralling lead acid batteries isn't a problem since they're normally float charge at a constant voltage, infact it doesn't even matter whether they're the same capacities or condition. Providing they both have the same number of cells they will be fine.

This isn't true for other chemistries like Liithium ion or Nicad because they're charged with a constant current source (or at least for one stage in the charging procedure).

 

[justDIY]

what is the duty cycle of a typical standby ups inverter (such as the one mentioned) ... something tells me they won't appericate continous serivce

also, I dont know about your smart-ups, but the seven I have are all rather loud when running in battery mode ... loud angry buzzing like someone put grapes in a microwave

 

[Nigel Goodwin]

loud angry buzzing like someone put grapes in a microwave

Grapes in a microwave? - are we all supposed to know what noise that makes?

 

[justDIY]

Grapes in a microwave? - are we all supposed to know what noise that makes?

google has your answers ... cutting right to the point

https://www.youtube.com/watch?v=lcOiaZbpFns

 

[audioguru]

I had my sound system turned up loud so I could hear the grapes. But a couple of American morons started talking and laughing.

I wonder why wet grapes would burn???
Maybe they quickly dried then the iron in them caused the big spark.

 

[justDIY]

lol, dumb loud americans!

the grapes weren't burning, the gases they were giving off were ionizing.

 

[simoin]

awesome bit of off topic ness ness

Grapes in a microwave, hands up who has too much time and is going to do that!

Anyway, the solar panel i have is only fairly small and would provide no wear near 240volts (Australian Standard) but, I have a 12volt 250a/h battery that will run just fine for a bit, might take me a few days to re-charge using the solar panel, but I am happy enough with that. This setup is more a toy than anything useful. Mostly I switch it on, on the weekends and let it re-charge during the week.

I will attach some photo's of it so you can see the various boards etc in another post.

So do we think this can be done? I agree that running it constantly under load would decrease it's lifespan but i won't be and if it does I don't mind

Simon

 

[simoin]

photo's of UPS at semi-dissassemebled stage

Hey Everyone, thanks for help so far, these are some photo's of the UPS at a semi-dissasembled stage (can't spell sorry). Let me know what other technical photos or what other information will be useful in assessing if this can be turned into a part time inverter.

What does an inverter actually consisit of, I can very clearly see (what I assume to be) the transformer, does the rest of the circutry do what?

Simon

 

[HiTech]

I had my sound system turned up loud so I could hear the grapes. But a couple of American morons started talking and laughing.

And understandably so from having a Canadian bent on what microwaved grapes sound like! We're too busy polishing our bullets down here!

 

[simoin]

Grapes in a microwave? - are we all supposed to know what noise that makes?

See slashdot article


Science: Everyday Objects Placed In a Microwave
Posted by CmdrTaco on Sunday November 19, @10:38AM
from the works-for-mythbusters dept.
It's funny. Laugh.
Tom writes "Everyday objects can produce interesting effects when you stick them in a standard microwave. Grapes spark, matches create superheated plasma fireballs, mini lightning-bolts arc between sheets of aluminum foil, and soap both splits open and puffs up, creating a somewhat vulgar spurt of bubbly excrement that has to be seen to be fully appreciated. However, as cool as microwave experimentation can be, balls of plasma and the like are bad for both your eyes and your microwave, so it's probably best not to try these things at home. update This site apparently is behind a really nasty popup that I missed (yay Firefox) the first time through. You've been warned... here it is but given the overall rottenness of the pop-up, I guess I wouldn't bother. Some folks know no shame. My apologies to the readers.

* Read More...
* 109 of 149 comments
* science.slashdot.org



Anyone had any more thoughts about the Sine wave UPS to sine wave inverter idea's?

 

[justDIY]

Anyone had any more thoughts about the Sine wave UPS to sine wave inverter idea's?

what exactly are your specific questions? google and the forum search function will provide you with all the mind numbing details of how a inverter works.

generally the UPS firmware is custom programmed to work with a specific battery (or set of batteries). If you cannot provide a matching replacement battery, your UPS will complain there is a problem with the batteries, and may not operate in backup mode. this is especially true with "smart" ups which have very sophisticated charging and maintenance circuits.

you've got an excellent and once very expensive UPS there ... find the proper batteries for it and use it as it's intended would be my best recommendation.

 

[qsiguy]

Not to distract from the purpose of this thread but the grape thing got me curious so I found a better video clip if anyone's interested.

https://www.youtube.com/watch?v=_ux8nSWmAz0&mode=related&search=

 

[audioguru]

1300W just to light up a little grape? It is the worst efficiency I have ever seen but it looks cool, especially with the glass trapping the plazma.