Time Code And Real Time Clock (Rtc) Powering - Nagra Seven Operating Instructions Manual

Time Code and Real Time Clock (RTC) powering.

The power supply circuit of the Nagra Seven is equipped with a "super capacitor" which is designed to maintain
the time of the internal RTC and the time code clock (If TC option is fitted) for about 10 minutes if the battery
of the recorder is removed. This ensures that the time code will remain accurate while the battery pack is
replaced. If the date and time is lost, then it will automatically be requested when the next power on is made.
Note: The external DC supply can be connected and disconnected at any time without any interference even
during recording.
Lithium-Polymer battery life and care
Lithium-Polymer battery packs will last for between 500 and 1'000 charge cycles before being replaced, which
if correctly cared for, in the case of a Nagra Seven would represents about 5 years or so of normal operation.
However there are some important points to be made concerning the "housekeeping" of such packs, to
guarantee their best performance.
Contrary to NiCd packs, the most damaging event that can happen to a Lithium pack is for it to discharge
completely. If this happens it is very likely that the pack will be irreparably damaged. In the Nagra Seven the
software will close the recorder down well before the battery pack gets to a critical charge point thus
protecting the cells. In addition, a security circuit inside the pack itself will also cut in should the pack get too
drained, however in any event running the battery flat is strongly inadvisable.
It should be remembered that even with the recorder turned OFF, the internal real time clock and Time Code
circuit (if fitted) WILL CONTINUE TO DRAW POWER from the pack. The time code circuit alone will completely
drain a fully charged pack in about 1 month.
A Lithium-Polymer pack will have a longer lifetime if it is regularly recharged (even when half full). It is not
possible to "overcharge" the pack. Unlike a NiCd battery, the "memory" effect does not exist with Lithium-
Polymer packs.
A charged battery pack, in good condition, can be stored, disconnected from the recorder, for a period of 1
year without risk. If one wishes to store a Lithium pack for an extended period at room temperature (a year or
more) then ideally it should be charged to about 50-70% before storage (suggested by the manufacturer). In
such a case, after 1 year the pack will have lost about 4% of its total capacity, whereas if the pack is charged to
100% before storage, after 1 year it will have lost nearly 20% of its total capacity. (At lower storage
temperatures, this effect is minimized). One should always verify from time to time that the pack remains at
around 50% and recharge a little as necessary.
So remember:
- DO NOT store the Nagra Seven for long periods with the battery box attached.
NEVER allow the pack to be drained completely.
-
- ALWAYS keep the battery charged as no harm will occur.
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