You can drive the unit directly from a car battery, provided you can get th=
e
power into the unit. You can make your own cable if you are very very very=
very very very very patient in soldering the Hirose 4-pin connector onto
any appropriate cable, and connect the cable to a lead-acid battery. The
700 series draws about 1 amp via external power, so 24 h * 1 A * 1.2
capacity factor =3D 29 Ahr battery (minimum). Car batteries don't discharge=
gracefully, so you'd need a deep-cycle (aka wheelchair, or golfcart, or
traction, or forklift, or solar, or photovoltaic) battery meant to withstan=
d
deep discharges without damage. The "capacity factor" I mentioned above is=
to make sure the battery never discharges past 20% capacity (voltage never=
below 11.5v).
I don't, of course, carry car batteries around, but there are nice solution=
s
by companies like Bescor that make belt- and shoulder-carried high-capacity=
starved-electrolyte lead-acid batteries for production needs. I have a 18
Ahr shoulder unit (2 6V motorcycle batteries in series, nice cover and
cigarette-lighter jack) that runs my time lapse camera about 36 hours, and=
will run it forever if I use my solar panel to charge the battery during th=
e
sunlit hours, not that I need to run it forever very often.
One very nice thing about the 700 series is that they handle external power=
failure perfectly, switching over to the LiION battery when external power=
fails (something my camera won't do), so if you need to momentarily
disconnect the external power (or if running directly from a solar panel,
when a cloud arrives) the recording is undisturbed. And the unit regulates=
input voltage internally, so you can feed it with dirty power if you need
(DC voltage with some AC in it), perhaps power coming from a portable
generator, or running an inductive fan motor from the same supply (for thos=
e
of us doing nature recording with a generator running nearby). Sound Device=
s
engineered the unit rather nicely. The only thing they could have improved=
(in my view) was to include two separate M-battery slots, so that when one=
battery dies it fails over to the other so you can change it out while the=
other is powering the unit, and doubles your battery life in the field.
Bruce Wilson KF7K
http://science.uvsc.edu/wilson
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