> The 744 started giving me low battery warnings around sunrise. I
> watched the display to see it switch over to the internal battery.
> Imagine my chagrin when it failed to do that and just shut down. It
> was the first time I've had a technical problem with the 744. It
> reported file system errors. I ran the repair utility but it wasn't
> able to fix the file. I sent the machine back to Sound Devices to see =
> what they could do. They explained that the voltage of lead-acid
> batteries rises after the load is taken off, and this confuses their
> switchover circuit. Perhaps when I'm also powering the MP-2 preamp
> from the battery that load will stabilze it. To be continued.
> -Dan Dugan
Hi Dan,
That is the exact problem I have had with my 722 and the various
battery packs I have made up of AA NiMH, AA Alkaline, and D Alkaline
batteries. It is good to know to expect the same from lead-acid. I
don't think SD tested their "seamless" switch over mechanism very
thoroughly. They told me a while back, they only recommend lithium,
but I am now skeptical that even with an expensive lithium system, the
results in the end will be the same - the continued corruption and
loss of important recordings. I don't know, does the voltage of
lithium not rise like other batteries after the load is taken off?
My workaround has been to set the file size limit fairly small. My 722
so far has only corrupted the last file of the session when the
failure occurs. I have not yet tried running off an external pack
without the attached battery installed, but that might at least close
the final file correctly.
John Hartog
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