Hi John--
Seems like SD would have provided more insight doesn't it,..
especially if switch-over problems turn out to be more frequent with
CF media? Perhaps some other 702 users can chime in with supporting
or contrary experiences. The 702's external power requirement is 1000
ma minimum, 10-16 volts. It seems like your 10- ~2000ma AA cells
would provide enough power to operate the recorder, at least for a
while. Perhaps the combined load of "topping-off" the internal
battery while powering the deck is part of the problem.
If the source of the switch-over problem is insufficient amperage
from your current external battery pack, maybe you could confirm this
by running it from an old car battery until its voltage drops below 9
volts and the recorder attempts the switch-over. You should also be
able to initiate a switch-over by disconnecting the external battery
while its recording. If you can get the 702 to switch-over reliably
and use the internal battery to close-out and save the files, your
external battery can be sized fairly conservatively. If not, you
might need a much larger external battery pack to insure you'll have
plenty of time to get there and manually close out the files. I'd
hate for you to invest in the pricey NiMH batteries and find out they
don't solve the switch-over problem. If you do need the assurance it
won't run out of power under any circumstances, a $25 lawn tractor
battery might be a better solution. Rob D.
=3D =3D =3D
At 5:58 AM +0000 5/27/08, John Hartog wrote:
>Hi Rob,
>My adapter is wired pin-1 to negative, pin-4 to positive as the 702
>manual recommends for use with an external battery pack. Wired that
>way, it does nothing until the recorder is turned on, at which point
>the external battery pack both charges (tops up)the attached Lion
>battery and runs the recorder until the external battery reaches about
>8.5V at which point a little roulette wheel spins inside the recorder
>deciding the fate of the file in progress.
>
>Replies from SD to my inquires suggest not using NiMH battery packs
>but Lion instead. They did not suggest that anything might be wrong
>with my recorder, which leaves me to assume it is normal for the
>battery switch-over circuitry (at least in 702 recorders) to be far
>from fail safe. I have not yet tried the SD users forum - but will soon.
>
>I have been using AA NiMH because that's what I have around, and did
>not want to spend money on a new battery/charger system. I liked the
>idea of keeping my external battery pack fairly small, providing just
>enough extra to get a full night of recording when combined with the
>attached Sony NP-F970 battery. I have tried several AA pack schemes
>now, and all have proven unreliable.
>
>For now I just need to put together a bigger battery pack - enough
>power to fill an 8GB card without needing the internal battery at all.
>I like your D-cell pack, so I'll probably give that a try.
>
>John Hartog
>
>--- In
><naturerecordists%40yahoogroups.com>=
m,
>Rob Danielson <> wrote:
>>
>> At 6:19 AM +0000 5/19/08, John Hartog wrote:
>> >Hi Rob, you say, "You can also set the "shut-off" voltage lower, like
>> >10 volts when you use the external DC input."
>> >
>> >Though I have not tried using an external pack without an attached
>> >battery also installed, at least on the 702 I think that setting you
>> >mention only changes the the low voltage indicator and warning alarm,
>> >but the switch over voltage (if I remember correctly, ~7 volts )is not
>> >changeable.
>>
>> I believe you are correct, John. The manual says the 744T
>> automatically switches to the internal battery at 9 volts. Starting
>> with a 14.4 - 18 volt battery pack extends the operation time
>> considerably over that of a 12 volt pack. The factory alarm setting
>> of 11 volts seems too high for my higher voltage/higher amperage
>> battery packs.
>>
>> >I still have not solved my battery switch-over problem that results in
> > >corrupted files.
>>
>> I've never had this happen-- no matter the powering situation as long
>> as I have a charged Lion battery installed. My 744T always closes
>> out the files on the HD and also tells me upon re-powering that it
> > powered down early and asks if I want to check for lost files on the
>> HD.
>>
>> How is your Hirose external battery connecter wired? Pin 1(-) and
>> 4(+) should provide power without charging the removable 7.2 volt
>> battery and the configuration of pin 1(-) and pin 3 (+) should
>> provide power and charge the removable 7.2 volt battery. I use the
>> later wiring on my primary Hirose cables because it encourages me to
>> start off both batteries fully-charged. The wiring shouldn't make a
>> difference but its the only thing I can think of that is not
>> programming related,.. Did you check the SD users forum? Rob D.
>>
>> >I set the file size limit to around <2GB to allow for
>> >easier DVD archiving: this has turned out to save me some important
>> >recordings as it is only the last file being written when the failure
>> >occurs that gets corrupted.
>> >
>> >John Hartog
>> >
>> >
>>
>>
>> --
>>
>>
>>
>
>
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