Chapter 7 Installation
Internal Standby Battery Maintenance
Operating and Programming Manual 129
Internal Standby Battery Maintenance
This section does not apply for 48V option instruments.
The 5071A uses two, sealed, 12-Volt lead-acid battery packs as an
internal back-up power source. These battery packs are designed
specifically for use with the 5071A. The battery’s operating time and
life can be optimized by understanding and following some guidelines
for sealed lead-acid rechargeable batteries.
Battery Shelf Life and Storage
When not in use, the internal standby batteries have a nonlinear self-
discharge rate. Additional discharge (always less than 500
microamperes), results from monitor circuits connected across the
battery, even when all power to the instrument is removed and the
battery disconnect switch has been activated.
Under these conditions (25 C), the useful storage life is roughly three
months, does not cause full discharge, and still provides at least 45
minutes of battery operation. The storage time required to deplete all
capacity is at least one year. Continued storage beyond one year could
jeopardize future battery operation or reduce the remaining number of
discharge cycles. For storage times beyond one year, always physically
disconnect the batteries from the instrument.
When disconnected, (shelf life at 25 C) the batteries may be stored for
up to two years without recharging. The permissible storage
temperature range is -65 C to +65 C, with storage life decreasing
rapidly as ambient temperature increases.
Battery Operating Temperatures
The battery pack(s) is designed for use between -40 and +65 C. At 25
C, the 5071A is specified to operate for at least 45 minutes. At 0 C,
the 5071A will typically operate for approximately 50 minutes. At 55
C, the instrument operates between 60 and 75 minutes.
For the operating temperature of 25 C, the battery provides 200 cycles
of operation with 100% discharge depth for each cycle (when the
5071A automatically shuts down). The battery will provide 2000 cycles
of operation at 25 C with 25% discharge depth for each cycle.
The expected battery service life (trickle charged by the internal
charger with few discharge cycles) at 23 C is approximately 4 to 6
years.
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