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Author Topic: Battery Power needed for a 744T  (Read 714 times)

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Offline nak700s

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Battery Power needed for a 744T
« on: June 22, 2017, 07:45:04 AM »
Hey now...

When using an attachable battery on a 744T, how low can the voltage remaining indicator go before the deck either shows signs of not having enough power or shuts off.  It hasn't happened yet, but want to make sure it never does.  I was told it shouldn't go below 7.2V, but that doesn't make sense to me since the batteries are 7.2V batteries.  Please advise.
Normal: Nakamichi CM-700's >> SD 744T (or) Sony PCM-M10
Stealth: CA-14c >> CA 9200 >> Edirol R-09HR
Ultra stealth: AudioReality >> AudioReality battery box >> Edirol R-09HR
Simple & Sweet!

Offline tim in jersey

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Re: Battery Power needed for a 744T
« Reply #1 on: June 27, 2017, 11:15:13 AM »
If memory serves, it gives a low battery warning @ 6.5v and powers off @ 6.3v.

All of my batteries display 8.1v when fully charged and I swap them out when they hit the ~7.0v mark as I don't like to deeply discharge li-ion batteries...

Offline GLouie

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Re: Battery Power needed for a 744T
« Reply #2 on: June 27, 2017, 01:18:04 PM »
Tim has a good memory!
Download the manual from the SD site. Pages 57-58 describe the warning at 6.5 volts and shutdown at 6.3. It's different if you apply power through the Hirose power jack. There's also beeps in the headphones unless the warning bell default is turned off (page 25). That can scare the poop out of you if you suddenly hear beeps (they aren't recorded, of course). My batts tend to start at 8 volts, and sit through the 7s for most of their operating time.
FYI, I use the 722, but this aspect seems to be the same for the 744T.

Offline nak700s

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Re: Battery Power needed for a 744T
« Reply #3 on: June 27, 2017, 01:43:26 PM »
Thank you gentlemen.  I did read the manual, but was more interested in on hand experience with the batteries, as someone told me not to let it dip below 7.2V and I wanted confirmation.  Now at least I know I can go for a full show (if push comes to shove), but will switch batteries given a set break.   :coolguy:
Normal: Nakamichi CM-700's >> SD 744T (or) Sony PCM-M10
Stealth: CA-14c >> CA 9200 >> Edirol R-09HR
Ultra stealth: AudioReality >> AudioReality battery box >> Edirol R-09HR
Simple & Sweet!

Offline GLouie

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Re: Battery Power needed for a 744T
« Reply #4 on: June 30, 2017, 12:16:59 AM »
IMO it's not an exact science.
My understanding is that the normal LiIon 2-series-2-parallel 4000mAh packs are not harmed down to about 3 volts per cell (6v for the pack). I think SD was being careful in choosing the 6.3v shutdown level for that reason. Also, I don't think the voltage vs. run time is very linear, and the quality of cells in the packs differ. Most seem to start going bad after a few years anyway. Genuine Sonys seemed to last longer, but they don't seem to make them anymore. I try to run on AC whenever possible (which is the majority of the time), but about once a year, I do a "run until it stops" battery test and make a note of it.

You can get humongus packs that fit the Sony L format.

Offline nak700s

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Re: Battery Power needed for a 744T
« Reply #5 on: June 30, 2017, 03:46:12 PM »
Thanks, that's good information and a good idea to do.  I don't use this deck in the field with batteries often. Like you, I use AC power as much as possible (although I will keep a battery installed for a security back-up).  Sometimes, however, I want the high quality in a open taping situation, so I need to know my limits.
Normal: Nakamichi CM-700's >> SD 744T (or) Sony PCM-M10
Stealth: CA-14c >> CA 9200 >> Edirol R-09HR
Ultra stealth: AudioReality >> AudioReality battery box >> Edirol R-09HR
Simple & Sweet!

 

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