2
Date: Sat Apr 27, 2013 10:04 am ((PDT))
Trond & all:
There is another issue with using external batteries with the DR-680 that y=
ou
need to be aware of.
If a lead-acid (AGM or gel cell) battery is left on well past its 'safe'
discharge voltage, the DR-680 does NOT deal with the low input voltage prop=
erly;
it doesn't switch over to the internal batteries as one might expect, until=
things are too late. As the external battery voltage drops, the recorded so=
und
is filled with increasingly large amounts of terrible glitches, then the au=
dio
mutes altogether. Not a pleasant thing to listen to.
There are two solutions to this problem with lead-acid batteries. One is to=
build an in-line circuit for the battery supply that cuts off the supply to=
the
DR-680 when the voltage drops to about 11.6 volts. Then the internal batter=
ies
will take over properly from the external battery. The other way is to use =
a
battery that has excess capacity to handle extended recording times before =
it
reaches its safe discharge voltage. My rule-of-thumb is to allow for about =
1 AH
of battery capacity for each hour of recording time, based on using 4 mics =
with
phantom power. You should be safe with that amount. As an example, I did a =
14
hour drop at Seney with 4 mics under phantom power using a 22 AH AGM batter=
y
with no issues. So use the biggest battery you can handle. BTW, the power
consumption of the DR-680 does not scale exactly linearly with the amount o=
f
mics used since the recorder uses a fair amount of power even when not usin=
g
phantom power.
My lab measurements put the power consumption of the DR-680 at 0.96 watts (=
800
mA * 12 volts) when using all 6 mic inputs with phantom power. So my
rule-of-thumb for battery capacity is pretty darn close. I always like to h=
ave a
safety factor when dealing with one-of-a-kind recording opportunities. :>=
}
I don't have any experience with using the BP160 lithium battery pack that =
David
has mentioned, but based on the data sheet one could expect about 15 - 16 h=
ours
of run time for the DR-680 using 6 mics with phantom power. The BP160 has
built-in circuitry that should mitigate any problems with the cutover to th=
e
internal batteries of the DR-680.
All of this boils down to price versus size and weight. One can buy almost =
five
22 AH AGM batteries that each have equivalent capacity to the BP160 battery=
pack, but they are heavy and bulky compared to their lithium counterpart.
As for toxicity, all batteries have some toxic chemicals within them. All
batteries should be disposed of at a proper disposal facility after they ar=
e no
longer usable. BTW, I have never had any health issues using and handling A=
GM
(lead acid) batteries. One can recycle them at many battery shops for free;=
the
internal contents are then used to make new batteries.
Finally, here are some links for the curious:
http://www.batteryweb.com/manuals/techman.pdf
http://batteryuniversity.com/learn/article/health_concerns
I hope that this helps to elucidate the subject of batteries and the DR-680=
.
Best regards,
Greg O'Drobinak
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