Batteries in Audio
Oct 16, 2010 0:38:04 GMT
Post by jkeny on Oct 16, 2010 0:38:04 GMT
Mike suggested that a thread on batteries & their use in audio might be of interest!
I have experimented with batteries in audio on & off for years using mostly Sealed Lead Acid types. I always found the noise floor reduced but the dynamics lacking somewhat. I read that the internal battery impedance was the main cause of this lack of dynamics & that some large & expensive SLA's did not have this problem. These proved to be too costly & unwieldy for me (WAF was negative too
When I came across the A123 LiFePO4 batteries I was initially attracted to them by their low internal impedance of 8mOhm & their size for a 2.3AH output. Their specs also specified high current output of 120Amps for 10 secs or 70A continuous. Their nominal output voltage of 3.3V suggested to me that they would be worth using as an experiment on some digital audio devices. They also don't suffer the potential problems of explosion & fire that LiPo batteries can suffer.
In order to test their noise characteristics I decided to use one for powering some digital audio 3.3V powered clocks - the most sensitive devices to power supply noise. It turned out to be a great success. I posted my results on DIYAudio.
Anyway, since then I have learned more about these batteries & am impressed by what I've learned.
Bear in mind these are one of the most researched batteries around as they were being considered for powering of electric vehicles. An important issue in this regard is their lifetime. The manufacturer stated that they have a 15 - 20 year life. Here are some links regarding this jackrickard.blogspot.com/2010/06/life-in-lifepo4-cycle-life-and.html
mit-evt.blogspot.com/2010/07/new-cell-cycler.html
As regards impedance across the frequency range I already posted a link to a paper showing impedance measurements out to 100KHz of 4mOhm (this is for 10AH LiFePO4 batteries & not 2.3AH A123 LiFePO4 batteries) The point of referencing it is that it shows the steadiness of impedance out to high frequencies.
I hope this detail on batteries might help as a point of discussion?
I have experimented with batteries in audio on & off for years using mostly Sealed Lead Acid types. I always found the noise floor reduced but the dynamics lacking somewhat. I read that the internal battery impedance was the main cause of this lack of dynamics & that some large & expensive SLA's did not have this problem. These proved to be too costly & unwieldy for me (WAF was negative too
When I came across the A123 LiFePO4 batteries I was initially attracted to them by their low internal impedance of 8mOhm & their size for a 2.3AH output. Their specs also specified high current output of 120Amps for 10 secs or 70A continuous. Their nominal output voltage of 3.3V suggested to me that they would be worth using as an experiment on some digital audio devices. They also don't suffer the potential problems of explosion & fire that LiPo batteries can suffer.
In order to test their noise characteristics I decided to use one for powering some digital audio 3.3V powered clocks - the most sensitive devices to power supply noise. It turned out to be a great success. I posted my results on DIYAudio.
Anyway, since then I have learned more about these batteries & am impressed by what I've learned.
Bear in mind these are one of the most researched batteries around as they were being considered for powering of electric vehicles. An important issue in this regard is their lifetime. The manufacturer stated that they have a 15 - 20 year life. Here are some links regarding this jackrickard.blogspot.com/2010/06/life-in-lifepo4-cycle-life-and.html
mit-evt.blogspot.com/2010/07/new-cell-cycler.html
As regards impedance across the frequency range I already posted a link to a paper showing impedance measurements out to 100KHz of 4mOhm (this is for 10AH LiFePO4 batteries & not 2.3AH A123 LiFePO4 batteries) The point of referencing it is that it shows the steadiness of impedance out to high frequencies.
I hope this detail on batteries might help as a point of discussion?