tadiran lithium battery packs for long term ocean...
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Tadiran Lithium Battery
Packs for Long Term Ocean
DeploymentsLee Gordon
Doppler Ltd.
858-486-4077
lee@dopplerltd.com
Long Term Ocean
Deployments
• Duration: weeks to years
• Instruments alternate low power standby
and high power operation
• Instrumentation is often designed for
alkaline battery packs, then investigators
decide they want more
Alkaline Pack for a
Doppler Profiler
Replacement PulsesPlus
Lithium Pack With 3x the
Capacity
20
25
30
35
40
45
6040200Time (days)
Volta
ge (
VD
C)
Alkaline
Lithium
Voltage Curves for a Typical Doppler Profiler Deployment
Everything about the deployment setup is the same, only the duration changes.
Capacity vs. Duration @ 20°C
TL6930
D Primary Cell
20C
0
500
1000
1500
2000
2500
0.0 5.0 10.0 15.0 20.0
Duration (months)
Ca
pa
cit
y (
WH
r)
TL4930
TL5930
TL6930
Capacity depends on current, which depends on duration (shorter duration
deployments using higher current)
Capacity vs. Duration @ 0°C
0C
0
500
1000
1500
2000
2500
0.0 5.0 10.0 15.0 20.0
Duration (months)
Ca
pa
cit
y (
WH
r)
TL4930
TL5930
TL6930
TL6930
D Primary Cell
Capacity vs. Temperature
TL6930
D Primary Cell
0
50
100
150
200
250
TL6930 Spiral Alkaline
D-C
ell
Capaci
ty (
kJ)
25C
25C
25C
0C
0C
0C
TL6930 self discharge at 25ºC is 0.7% while spiral and
alkaline cells have 3% self discharge.
Hybrid Layer Capacitors (HLCs):
Capacitors or Rechargable Lithium Cells?
0 0.5 1 1.5 2 2.5 3 3.5 40
200
400
600
800
1000
1200
HLC voltage (VDC)
Sto
red c
harg
e (
Coulo
mbs)
1400F
500F1400F
500F
HLC1550A
dVdt
=iC
=dQdt
1C
HLC1550A (AA)
~1 A 10 min 3.9-3.5 VDC
HLC1520A (0.4 AA)
~0.25 A 10 min 3.9-3.5 VDC
HLCs are rechargeable lithium cells, but over narrow
voltage ranges, they behave like high-value capacitors.
Voltage Curves for a Typical Doppler Profiler Deployment
1: Primary lithium cells
2: HLC
3,4: Schottky diode
5,6: PTC (positive temperature
coefficient thermistor)
7: Voltage cut-off circuit
1 2 43 5
6
7
BranchSchematic of a typical PulsesPlus
battery pack.
Cells are organized by branches
instead of strings. A branch holds
primary cells, wired in parallel,
which charge one or more HLCs.
Tadiran PulsesPlus cells and packs have no fuses. PTCs protect like
fuses that reset automatically when you remove the overload.
Cutoff circuit
• Turns off the pack when it is about 97% depleted to prevent reverse currents in
branches. The pack holds the remaining charge for more than a decade.
• Uses insignificant battery power (much less than the battery pack’s self discharge).
• Protects against short circuits (but not too hastily!). It cuts off the pack after 100 µs
at >8 A and turns the pack back on when the load is removed.
• Provides an LED status indicator (pack OK and new, used, or depleted). Simply
short the pack to run this test.
• Internally records voltage and temperature to provided estimates of how much of the
pack’s capacity has been consumed.
This circuit is primarily useful for production ocean instrumentation. If you are
confident you can recover your system before the pack depletes, you do not need one.
Model Schematic
BatteryPrimary
CellHLC
SteadyLoad
PulseLoad
On 1 s, off 9 s
0.1Ω100Ω 300Ω1M
12V 0.1F
This model is not intended to reproduce a specific battery pack, but rather is
intended to illustrate how HLCs enable the pack to supply more of its capacity to
the instrument as opposed to internal dissipation.
Model Results: Comparison With & Without the HLC
10
0 2 4 6 8 10 12 14
Dis
sip
atio
n (
W)
Battery
Load
HLC
0
10-1
10-2
10-3
10-4
10-5
10-6
10-7
0.00
0.05
0.10
0.15
0.20
0.25
0.30
0 2 4 6 8 10 12 14
Time (s)
Dis
sip
atio
n (
W)
Battery
Load
Battery25 %
Load75%
Battery3.3 %
HLC0.03 %
Load97.7%
Without the HLCs, 25% of the battery capacity is dissipated by the primary cell’s internal resistor. With
the HLCs, the internal dissipation drops to 3% and most of the energy goes to the instrument.
Differences
Between Low
Current and High
Current Primary
Cells
Cathode
Insulator
Electrolyte
Anode (Lithium)
Spiral WoundPrimary Cell
(High Current)
BobbinPrimary Cell
(Low Current)
Bobbin cells are simpler, less
expensive and, because they
hold more lithium, they store
more energy. Spiral-wound
cells supply high currents by
building the battery in
sheets. The large surface
area also increases self-
discharge and increases the
chance of shorts between the
cathode and anode. The
ability to source high
currents mean that shorts
can become explosive.
Hermetic Seal Prevents Leakage and Outgassing
Glass seal between
anode and lid
Laser weld between
lid and can
Pack Mechanical Design
Lithium Packs need just a little more room, so plan ahead
2.5 mm
Alkaline cell
Lithium cell AA HLCs1 mm gaps
AAA HLCsno gaps
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