Help with crazy battery power experiment

[DanG]

I have this Power Station with 120 watt DC to AC inverter. I picked it up from Gadget Universe as part of my hurricane supplies for down here in sunny Florida. It's good for when the power goes out, and it'll provide a boost for the car, too.

A sealed lead-acid 17 amp/hour battery providing a 600 amp peak boost rate.

I tested it yesterday 'cos the power was supposed to be out in my condo. It's got a switch that turns on the inverter, it sounds like a little fan. Plug in your lamp, and viola!, there was light.

It occurred to me maybe I could try plugging my stereo into this, to see what all the hullabaloo about battery power for stereo is about.

My configuration:
Power Station
Monster Power HTS 1000
Yamaha A-760II integrated amp: power consumption 350 W/850 V A (80 W / ch.)
Mission Cambridge TT

I don't know what I'm doing here. Is this crazy? I don't want to blow my system. Will it work?!

Thanks for the help!

Dan

[Sckott]

Doesn't sound Kosher. Most every time I read about power tweeks like this, it's a battery buffer in front of the AC. So, in instance, like with some of the Terres Turntables, they use a DC driven motor, and when the motor's off, the battery charges. With amps, same kinda thing, except the amp works off of capacitated AC storage in DC cells. The AC is right behind it, but the capacitence is used as a buffer.

Got a feeling you'll floor the battery power, as most of those power stations will only use the DC current when the AC power is removed. Then, you have a limited time before it goes bye-bye.

[Claviusb]

Moved to the appropriate area. Tom Port is the guy who knows about battery power. Maybe he'll comment on what you're doing...

[Richard Feirstein]

Run, don't walk away from this exercise. It is one thing to supply DC power to a tube amp designed for DC operation, it is another thing to use AC power from a power converter. You are not testing battery power at all but merely the impact of a less then well regulated AC inverter. Your power company likely does a much better job at power regulation. A good AC inverter can cost thousands of dollars.

[kim kerwin]

I can tell you from personal experence that battery power takes your stereo to a new level of listening enjoyment, and yes Tom Port is the man to discuss this with. He has an inverter that produces a perfect Sinewave that I think is a 60hz. I'm not sure of that, but I think that's the correct info. The inverter runs off of a 12 volt battery, similar to a marine type. Tom runs everything but his tube amps ( they draw to much power ) on this set up. It's really amazing how distortion free it is. The power that comes out of our walls really sucks. We've listened to plenty of power conditioners and they don't come close to the benefits of battery power. Give him a buzz if you've got any questions, Kim

[Robert44]

Yeah, it will work.

I'm assuming you're not trying this as a permanent set-up, only for power interruptions to keep the tunes going.

Capacitive or inductive loads (like your TT motor) don't really like most power inverters because the supplied waveform is not sinusoidal.

NO solid state power inverters that have any power transfer efficiency put out a pure 60Hz sine wave; the best they can do approximates a switching power suppy that has quite a bit of high frequency noise.

That said, the power supplies in your components are remarkable low pass filters; any HF noise on the line is taken care of by the large inductance of the power supply transformer.

Just don't try running the air conditioner or the fridge off the thing....

[Richard Feirstein]

I have a company that from time to time makes such inverters for specific applications and they can add somewhere between $25,000 to $85,000 to a project. They are used for prototype development of equipment for high speed motors, turbine generators and the like. I have not tried to take one home for my stereo. There is a lot more to it then just developing a circuit to put out a pure 60Hz sine wave. At the industrial level we deal with three phase power, and it is not all that bad for typical applicaions. It is not that hard or expensive to build a well regulated AC to DC power supply, believe me. But try to build power regulation for a high speed, compact, ultra high output motor; now that's a trick. (Which is why you don't see them outside of a few military applicaions, and a few blower, compressor commercial applications).

I have no experience with today's audio applicaions but see no need to start with battery power, as I noted, quality inverters and AC to DC power supplies are not that hard to design or produce. Weight, heat, and cost are the major issues, not output quality. Mr. Carver's amp designs that use variable voltage is very interesting and solves many of these problems for consumer power amp products. Good designers are not easy to come by. My Denon 3802 has a very well designed and executed power supply section and I doubt battery power would make any difference I could hear or measure. My former receiver would heat up and literally dim its display lights in time with the music when asked to deliver close to its rated power, a poorly designed power supply was its cause, but it was adequate for typical use. It had more than adequate transformer capacity and mass but poor current and voltage regulation.

[DanG]

I'm not sure I've been clear, or possibly I don't understand the comments that have been made.

The hypothesis to this experiment is to see if there is a listenable difference to me in my stereo when it is powered by regular AC power, or when it is powered by this Power Station.

Battery power is enticing, but perhaps cost prohibitive. I thought here was a way to check it out on the cheap. But one clear possibility is that the Power Station does not represent a good choice of battery power; in fact, it may damage my stereo.

Sckott posted:
... it's a battery buffer in front of the AC.

Well, this Power Station charges from being plugged into the wall, but it's meant to be used as a stand-alone source of power, not plugged into the wall. So I don't think I would be using it as a buffer in front of an AC power line.

Richard Feirstein posted:
You are not testing battery power at all but merely the impact of a less then well regulated AC inverter.

A rechargeable battery is not a battery? I'm not trying to smart off, I really don't know. Wouldn't battery systems designed for stereos recharge? My marine battery is rechargeable, this Power Station just seems like a lead-acid battery that inverts its DC charge to AC, suitable for powering AC devices.

So, limited battery power, cheap inverter to produce AC, conditioned by the Monster 1000. The Yamaha is not a tube amp.

First expectation: limited time before the battery runs out.

Second expectation: It will power the stereo.

It seems to run a 3-way lamp just fine. Maybe a prior experiment should be to run the lamp for half an hour, see if I notice any differences in the lamp from regular AC and this Power Station.

I've taken to unplugging the microwave and dryer when I turn on the stereo, it's easy to do and I hear a difference. Theoretically the Power Station avoids interference inherent on regular AC power lines because it is stand-alone, however, will it introduce its own noise and damage my stereo?

Thanks for your comments so far, just mulling over the experiment has been enjoyable. :p

[Richard Feirstein]

Sorry I did not make my point clear. There are DC products out there. Parts of the USA were still connected to Edison's early DC generators up until about 25 years ago in NYC and parts of Brooklyn!

There are TV's and other AC/DC products out there that do not need an inverter; they run off DC. (You may need a DC voltage degulator since most today are 12 volt and not 120 volt).

If you use batteries to power a DC power amp or whatever instead of inverted AC to DC power you will be testing the inverter.

If you use batteries to power an AC power amp you need a DC to AC inverter and you will be testing the inverter.

If you need to change DC voltage you will not be testing battery power but the DC voltage regulation circuits.

If you had a receiver that was designed to run off 12 volts DC or 120 volts AC 60/50 Hz you might have a toy you could try your experiment with. Expect less max power output from the 12 volt DC source and you will need very heavy power supply wires. Have fun.:cool:

[aashton]

I keep thinking of trying out Solar or Wind power for the house (more wind than sun in the UK :( ) - I didn't want any DC equipment so would have gone the inverter route.

The suitability for audio equipment all boiled down to the shape of the output wave - if it outputs a "true" sine wave then that appears to be the optimum. This site here gives a little pros and cons diagram of the three main output types

http://www.almac.co.uk/proven/PAGES/invert.htm

Last year the bulk of inverters seemed to be of the "Modified sine wave" variety and many stated that they were not suitable for computers and delicate electronics.

I'm not sure if I have got the right end of the stick but good luck in your test.

All the best - Andrew

[Richard Feirstein]

Do note that a pure sine wave is the aim, but it is not that simple. The lag between voltage and current and a host of other complex and related characteristics all add together to define power output. This is why the claims of many of those overpriced home power conditions are a bit of a joke. Many of those making their claims seem to have but a superficial understanding of what they want you to think they have mastered. In most areas of the USA the utility power grids supply relatively high quality power for home use. There can be individual problems cause by defective transformers and bad connections, but the local utility should be able to cure those with your input; really.