Power conditioner plugged into computer battery

APC recently introduced a series of power conditioners specifically designed for audio/video applications.

Their "S" Type AV Power Conditioner with Battery is pretty much exactly what you are looking for: "Pure sine-wave battery backup, surge protection, isolated noise filtering, and voltage regulation all combine in a single unit to deliver pure, uninterrupted power for high performance AV, home security, and automation systems."

I have been running its little brother - same without the battery back - since November and am very pleased with it. The system sounds very, very good...

http://www.apc.com/products/category.cfm?id=15&segmentID=1

Please note that the APC unit provides a pure sinewave - as opposed to square wave power. Sinewave is what you need - computers don't care, and it is more expensive to produce sinewave power.

Secondly if you search the Forums you will see that almost all UPS, isolation transformers and the like limit current.

As Mr Hosehead suggests, it may be that once the UPS reaches full charge it will simply pass current straight through - there are only two ways to verify that, either measure it yourself or talk to the manufacturer. Since that would increase the cost and complexity of the unit with no benefits for its target market, my experience suggests that its unlikely.

The one way I know how to do it for sure is to use a 2,000-3,500w sinewave inverter tied to a large 12v battery bank. This type of unit which is designed for off-grid and marine applications, has a very fast switchover from the AC mains to the DC banks. It is also large, heavy and relatively expensive.

Finally I have compared the APC to both Equitech and BPT - the APC product is unique in that it is the only audio/video product that I am aware of that has a battery back-up. (This includes Running Springs, Chang, Gray etc)

Your engineering premise is fine - you just won't find what you are looking for at a low price point.

I am not an EE - most of what I know about this stuff I learned working power issues on my sailboat. Inverters, batteries, alternators and 110. It is an unholy brew.

I understand what you are trying to do. I believe APC has done it for you.

BUT If you would rather roll your own (heck that is half the fun) then I suggest you just hook it up and see what happens.

Your comment that you can't power up your whole system without blowing the UPS suggests that the only thing you can do is to get a much bigger UPS - in the 2-3K watts range as you might find in corporate server environment. Perhaps the larger reserves will also help with any potential current limiting.

Please keep in mind that you are getting into the land of batteries - lots of juice costs lots of money, takes lots of space, maintenance etc. I am looking at the APC site and to get to 3375W they are using 208 in. The unit - without shipping or install is $3,350... Typical back-up time at full load is 6.4 minutes (no typo six point four).

http://www.apc.com/resource/include/techspec_index.cfm

One could come to the conclusion that the reason this product doesn't exist is because there is no real return on investment. Frankly it would be a lot less expensive and considerably more sonically effective to just run a couple of dedicated 20amp lines to your listening area.

You know - think this through - nobody makes what you are looking for...