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