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T.007: 5.c Pre-test Battery Calculations
rescueME EPIRB1 Battery Calculations for Cospas-Sarsat
Beacon manufacturers declared maximum allowed cell shelf-life
(from date of cell manufacture to date of battery pack installation
in the beacon)
Declared beacon battery replacement period (from date of
installation in the beacon to expiry date marked on the beacon)
Battery pack electrical configuration
Cell model and cell chemistry
Nominal cell capacity
Nominal battery pack capacity
Annual battery cell capacity loss (self-discharge) due to aging, as
specified by cell manufacturer at ambient temperature
Calculated battery pack capacity loss due to self-discharge:
LCBN =CBN - [CBN *(1 - LSDC /100) ^(TBR+Dcage)]
Number of self-tests per year NST
Average battery current during a self-test IST mA
Maximum duration of a self-test TST sec
Calculated battery pack capacity loss due to self-tests during
battery replacement period: LST = IST*TST*TBR*NST / 3600
Maximum Number of GNSS self-tests between battery
Average battery current during a GNSS self-test of maximum
Maximum duration of a GNSS self-test TGST sec
Calculated battery pack capacity loss due to GNSS self-tests
during battery replacement period: LGST = IGST*TGST*NGST /
3600
Average stand-by battery pack current
Other Capacity Losses
Battery pack capacity loss due to constant operation of circuitry
prior to beacon activation: LISB = ISB*TBR*8760
Calculated value of the battery pack pre-test discharge
= LCBN + 1.65*(LST + LGST + LISB)/1000 + L
*Additional current drawn by the water contacts when activated.
S Nolan Technical Director Ocean Signal Limited
th
6
August 2014
Report 14/171 - Issue 3
Characteristic
/1000
OTH
Designation
Units
TCS
Years
TBR
Years
2 parallel packs each of 3 123 cells in
series
Q-Lite CR123A
Lithium Manganese Dioxide
A-hrs
CBn
A-hrs
Lsdc
%
Lcbn
mA-hrs
Nst
Ist
mA
Tst
Sec
Lst
mA-hrs
Ngst
Igst
mA
Tgst
sec
Lgst
mA-hrs
ISB
mA
L
mA-hrs
OTH
Lisb
mA-hrs
LCDC
LCDC
mA-hrs
PE TC "Omega"
Value
Comments
2.5
12.5
1.7
3.4
Increase over Cell
Manufactureres data
(0.46%) agreed
between C/S and
0.84
Ocean Signal
404.10
12
40.75
16.50
28.016
12
11.5
315.5
12.09
2.00E-05
14.4
Not Originally
Calculated*
2.19
488.30
Page 232 of 337
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