Chapter 1 - Getting Started
Battery Backup Unit
17
The battery control circuitry has constant current, constant voltage (CCCV) charger.
The battery charger provides a maximum 250mA charge current. When the charge
current falls below 16mA, the charger determines that the end of charge has been
reached, generates an end of charge indication and shuts itself off. If the battery
voltage drops below 3.0V, a complete battery discharge is indicated.
The battery control circuitry includes a battery safety circuit. The safety circuit
protects the battery by limiting the over-voltage to 4.3V, the maximum discharge
current to 3A for catastrophic events, and the minimum battery voltage to 2.35V. If
any of these conditions exist, the safety circuit disconnects the battery. These
conditions will only exist if there is a hardware fault present, and would never be
seen under normal operating conditions. In addition, the battery pack utilized, part
number 44-9-95611001, includes a resettable polyfuse that trips when the current
exceeds 700mA at room temperature. This protects the 1 amp rated connector
when for example a partial short exists caused by aa component failure.
Lithium Ion batteries have no requirement for conditioning, even after partial
discharges. The current battery pack utilizes a Renata ICP883448A-SC cell, with a
nominal capacity of 1150mAh. For a completely discharged battery, the charge time
is approximately 5 hours. Under lab conditions, current draw was measured for
different configurations of memory. The table below shows the results of those
tests, and the expected backup time is indicated for the specified memory
configuration. The table shows the absolute maximum backup time calculated from
the current draw measurements. The “Expected Safe Backup Time” is the absolute
maximum de-rated by 50% to account for different operating temperatures and
capacity reduction due to battery charge/discharge cycles. This is the time that
should be used when developing a system level power backup plan.
BBU Battery Hold-Up Times
Configuration
Memory Vendor and
Part Number
Measured
Current Draw
Absolute Maximum
Backup Time
Expected Safe
Backup Time
Main board
only w/512 MB
Kingston
KVR100X72C2/512
27.9mA
41.2 hours
20.6 hours
Main board
w/512 MB and
Coprocessor
w/512 MB
Kingston
KVR100X72C2/512
48.3mA
23.8 hours
11.9 hours
imageRAID.book Page 17 Tuesday, September 23, 2003 4:08 PM
Содержание IRF-1D series
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Страница 8: ...Table of Contents iv imageRAID book Page iv Tuesday September 23 2003 4 08 PM ...
Страница 164: ...Chapter 6 Maintenance Replacing the Enclosure 152 imageRAID book Page 152 Tuesday September 23 2003 4 08 PM ...
Страница 168: ...Appendix A Technical Information Specifications 156 imageRAID book Page 156 Tuesday September 23 2003 4 08 PM ...
Страница 180: ...Index 168 imageRAID book Page 168 Tuesday September 23 2003 4 08 PM ...
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