Battery Powered Front End - Off The Grid

[The Computer Audiophile]

Hi Guys - I'm researching powering my front end, preamp and DAC at least and amp if possible, from batteries. I just spent about an hour looking for solid information but did't find what I was looking for. I'm sure it's out there I just didn't find it. I'm not interested in powering my computers or music servers from battery yet, just the components.

 

 

 

Does anyone have experience powering components from battery?

 

 

What's needed to do this?

[AudioDoctor]

I am researching powering an entire home off batteries/wind/solar and anything else I can figure out. I guess that would also include the audio equipment. So far, all I have is a UPS for the computers and external HDDs...

[Julf]

Hi Guys - I'm researching powering my front end, preamp and DAC at least and amp if possible, from batteries. I just spent about an hour looking for solid information but did't find what I was looking for. I'm sure it's out there I just didn't find it. I'm not interested in powering my computers or music servers from battery yet, just the components.

 

I am assuming that is for potential sound quality benefits, rather than to protect against power outages and brownouts? In that case the usual solution of a battery-powered mains inverter won't do it. While the rest of the stuff is probably easily powered from 12 V, the big issue will be the amp that will need a voltage higher than the normal 12 or 24 V, and at reasonable power levels. The highest battery voltage I have experience with is 48V (the standard in telecomms exchanges and data rooms) - OK for an efficient (bridged) D-class amp, but not enough for a high-powered class A or A/B amp, not to mention a tube amp...

[sandyk]

Chris

You would need to have schematics, or more information about the devices, such as do they use + and - supply rails,

or a single +VE supply rail,the supply rail voltages etc. Sometimes you can replace a centre tapped A.C. wallwart with a + and - supply, and the internal bridge rectifier will steer the voltages appropiately.

Alex

 

Julf

Most Telephone Exchanges in Australia floated their 48V batteries at -52.6V and a a little higher.

Some of the larger exchanges had 3 or more banks of 2,200 AH 2V cells. Many older exchanges also had a smaller battery for +52V which was used for metering purposes.

I often wondered how my then 100W amp that used + and - 50V rails would sound like if I hooked it up to the Exchange supply.

[Julf]

You would need to have schematics, or more information about the devices

 

Schematics would definitely help, but often just opening up the device and having a look at the power supply, plus a few measurements with a voltmeter can be enough to figure out what is needed.

 

Most Telephone Exchanges in Australia floated their 48V batteries at -52.6V and a a little higher.

 

Not just in Australia. The standard is a nominal 48 V, but just as with 12 V car batteries that typically run at 13.5 V, the floating voltage is higher than the nominal voltage.

 

 

Some of the larger exchanges had 3 or more banks of 2,200 AH 2V cells.

 

Not quite submarine-class, but....

 

I often wondered how my then 100W amp that used + and - 50V rails would sound like if I hooked it up to the Exchange supply.

 

Well, you would need 2 banks of batteries to do the + and - feeds.

 

If the concern is trying to improve sound quality by isolating yourself from mains noise, the problem is that you don't want a floating charger connected, conducting the mains noise past the battery (batteries are not good at filtering HF). Just cutting the connection between battery and charger is a bad idea, as most floating chargers dislike running with no load - so you really need to switch off the charger.

 

If we are really talking about proper "off grid", then the next discussion will be the sonic characteristics of different diesel generators

[dimsal]

Chris,

Checkout it this component from Red Wine Audio: Black Lightning - High-Current Battery Power Supply

[JeffH]

Chris,

 

Here are a couple of companies that might be able to give you some advise.

 

Gary Dodd, Dodd Audio, sells a very popular battery powered tube buffer and other DIY kits. And, I have heard great thing from people who power their Virtue Audio amps with the battery kit they sell. Virtue Audio has a forum on audiocircle.com and there is always a discussion going on about battery power.

[Julf]

Checkout it this component from Red Wine Audio: Black Lightning - High-Current Battery Power Supply

 

Unfortunately that is only a solution for the "easy" 12/24V devices.

[Julf]

I often wondered how my then 100W amp that used + and - 50V rails would sound like if I hooked it up to the Exchange supply.

 

That is pretty much what Chris would have to do to power a power amp. To achieve 100W output power, the amp needs to put out 20V into 4 ohm, or 28V into 8 ohm. That definitely means at least a 48 V supply, probably a 2 x 48 V one. So 2 banks of 48 V telecoms batteries, with 2 floating chargers. I guess battery capacity needs to be 20-25 AH to give decent listening time.

[wgscott]

Hi Guys - I'm researching powering my front end, preamp and DAC at least and amp if possible, from batteries. I just spent about an hour looking for solid information but did't find what I was looking for. I'm sure it's out there I just didn't find it. I'm not interested in powering my computers or music servers from battery yet, just the components.

 

 

 

Does anyone have experience powering components from battery?

 

 

What's needed to do this?

 

I've been thinking of assembling the following, along these lines, for a proof of principle:

 

1. Laptop (has a battery).

2. DAC with battery source (shouldn't be that difficult).

3. Dodd tube buffer for passive attenuation -- designed for use with a battery.

4. Class D Audio amp kit with their 12 V battery-powered power supply -- already optimized.

 

I

[HiFiInsider]

A lot of DACs on the market are 12v - 14v DC so that should be easy to power off batteries. Add a MacBook and you should be pretty good. My Apogee Mini DAC and I think the new Wadia 121 is also DC.

[dallasjustice]

Veloce LS-1. I will have one to listen to in my system in the near future. I am not sure you would need to have the DAC and pre both running on batteries. I would think the power regulation after the battery is also very important. I guess it's the implementation that matters most.

[dallasjustice]

I used to have a battery powered ASR Emitter II amp. I cracked the battery case open to replace the 6 batteries. The power regulation after the batteries is very elaborate. At the end of te day, the ASR is a good amp that sounds better on batteries. However, there are many better sounding options, IME.

[cjf]

Another option to do this would be to go a similar route that is found in a modern Data Center where you have a (In your case) mini "Room" UPS that feeds standard AC outlets from its main batteries. This would allow you to "Float" these AC outlets off the grid while still maintaining a constant charge that would be more than adequate to feed any home audio equipment.

 

Granted, I'm not talking about a multi KvA unit but something big enough to serve the purpose.

[The Computer Audiophile]

Hi cjf - That's more of what I'm thinking about. I want to be able to plug any of my components into standard outlets.

[AudioDoctor]

I have just been made aware of this:

 

Riches to Straw » Whole-house batteries from Panasonic

 

I am in the very early planning stages of building my own home, off the grid, and powered with solar and wind, with a battery to store the energy. Something like this, with hopefully at the time I actually do this, more efficient batteries capable of more current over a sustained time.

[Julf]

Hi cjf - That's more of what I'm thinking about. I want to be able to plug any of my components into standard outlets.

 

In that case, be aware that a lot of the inverters (that turn the battery voltage back up to mains voltage level) don't actually produce a clean sine wave, but a rather nasty waveform with lots of harmonics. Not sure it matters with your equipment, but a concern for those who worry about power quality.

[The Computer Audiophile]

I'm very concerned about power quality.

[AudioDoctor]

In that case, be aware that a lot of the inverters (that turn the battery voltage back up to mains voltage level) don't actually produce a clean sine wave, but a rather nasty waveform with lots of harmonics. Not sure it matters with your equipment, but a concern for those who worry about power quality.

 

Could you plug something like a PSAudio Power Plant into it, and plug your equipment into that? You, would get clean power... Not sure if there is some reason it would not work for some reason I am unaware of.

[Julf]

Could you plug something like a PSAudio Power Plant into it, and plug your equipment into that? You, would get clean power... Not sure if there is some reason it would not work for some reason I am unaware of.

 

That would work. Not cheap. In essence anything that totally regenerates the mains power waveform would be OK. Even a filtering power conditioner might be enough, if you pick an inverter with a stable 50/60 Hz oscillator and at least a "staircase approximation" waveform generator (as opposed to the cheap square wave based ones).

[coot]

delete

[coot]

Could you plug something like a PSAudio Power Plant into it, and plug your equipment into that? You, would get clean power... Not sure if there is some reason it would not work for some reason I am unaware of.

 

How is that better than to skip the batteries and just go with the Power Plant directly from the wall?

[Daphne]

I have some basic knowledge about batteries. Not enough to say this is the exact battery you should be using, but enough knowledge to say this is not the type of battery you need.

 

You would not want to use flooded batteries in a home environment because they need to be kept in a vented area and require weekly checking of fluid levels.

 

That leaves sealed batteries (somewhat misleading because all lead acid batteries have vents) like Gelled cell or AGM. These batteries are available in deep cycle versions which have the ability to deliver reliable current over a longer period of time. They can be discharged by 80% and recharged many times with an expected life span of 5 to 8 years or even longer. To obtain enough amp hours which will reduce the amount of charging cycles one would need to connect lower voltage batteries in a series to form a bank, then several banks in parallel like used aboard a large sailing yacht, or energy storage for whole house power.

 

To supply enough power to feed the demands of a power amplifier you would need to consider 24 or even 48 volts DC. Then you need a high quality inverter that can deliver a clean sine wave (note: the term pure sine wave is attached to almost every inverter and can be misleading). High quality inverters can be found from the marine industry. Inverters designed to deliver clean power to single sideband radios, satellite communication equipment, etc. There are also quality inverters designed for home use but one would need to check the specifications closely.

 

One may also be able to use Lithium or NiCad batteries and depending on the type, can last up to 20 years. Nickel or lithium-based batteries are smaller, have a long life span, require less maintenance, with double to three-times the specific energy, offer better cycle performance and shorter charge times than lead acid batteries, but are expensive for the capacity demanded by a power amplifier, maybe $500 to $1200 each, and require a special charger and inverter.

 

The correct battery charger is a most important factor. Each type of battery requires a very specific charge rate and voltage. A good way to ruin a battery in a single day is to use the wrong charger.

 

In my opinion, if this was my project, I would be researching Lithium batteries to power components. Lead acid batteries are large, heavy and better suited for use as whole house power off the grid. Also consider who would want very heavy batteries 5 or 10 times the size of an audio system lined up against the wall or in a rack. Then they emit a foul odor and need to be confined in a cool vented area outside a listening room.

 

There are a number of companies that can supply a turn-key system of batteries, chargers, and top quality inverters. There is also a number of charging options like wind and solar power. You can go simple or as sophisticated as you want.

 

For some resources on batteries:

 

A good amount of battery information: Battery Information Table of Contents, Basic to Advanced

 

Deep Cycle Battery information from a general supplier who can actually supply a turn-key system for AC sensitive components like radio, stereo, and home theater equipment: Deep Cycle Battery FAQ

 

A comparison of different types of batteries:

Deep Cycle Battery Comparison

 

Concorde sealed AGM batteries: Lifeline Batteries - Marine & RV Deep Cycle AGM Batteries

 

Rolls – Surrette batteries: Rolls Battery. One Mean Battery.

 

Samsung lithium batteries:

Samsung SDI | Lithium Ion Battery - Samsung Rechargeable Li Ion Battery

[JohnMH]

I have a Xantrex sine wave inverter / charger in my 25 foot Airstream trailer. This is supposedly a good sine wave inverter that will, with sufficient batteries connected, supply the full 30 amperes the trailer can use. I've noticed that when running audio / video equipment I sometimes hear a high pitched tone in the audio, which might be because I'm usually either plugged into house AC mains or a Yamaha generator, thus some sort of charger generated noise? I'll have to try it disconnected from external power and operating on batteries only. Seems like the best thing would be to avoid the inverter stage completely and run off the battery DC directly to the max extent possible, with the charging equipment disconnected. To do what you want Chris - running 120 vac equipment as intended - I think you'll have to have a very good exceptionally clean sine wave inverter.

[The Computer Audiophile]

Thanks for all the info Daphne.

 

One battery a colleague just told me about is the U Charge from Valence. It's an LiFeMgPO4 (Lithium Iron Magnesium Phosphate). They are not cheap, but supposed to be very good.

 

http://www.valence.com/

 

However, now that I've read the responses above it appears the inverter maybe more important than the batteries.

 

Fun stuff :~)