Rebuild UPS to battery PSU?

[Tazzy]

I've got this APC 300va ups lying arround. I'm woundering if it would be easy to rebuild the UPS to a battery PSU?

I need 12-0-12 for a project and it has a 12v 7.4 mah (i believe) battery.

[joensd]

I also still have such an APC thing lying around.
Thought about the same but:
You could basically leave in the charger and the battery and you´re done.
But this will leave you with a basic 12V PS which won´t get you far.
You´d need another battery and another charger.

But one battery is a start isn´t it?

Cheers
Jens

[li_gangyi]

you can rip out the bat...but can you send me the inverter part?? Lolx...

[Tazzy]

Why would I need a second battery?

Does this mean I can't make +12 0 and -12 out of 1 battery?

Before reading what the LM7912 does exactly I thought I could use one to invert polarity.

At the moment I'm a bit lost, I don't see how I can make +12 into -12?

[li_gangyi]

you could use a SMPSU chip in inverting mode to get -12V...but it wouldn't work well in your case as you are drawing a large current and typically it's also not suited for "audiophiles" because of the switching noise that it makes...you cannot use a 7912 to get -12V...it has to be connected to another battery...and by the way...the 7912 must have a higher voltage for it to regulate properly...and if you are gonna use it for an amp...I believe the 1A current capacity that it has is insufficient...