Lithium-ion battery technology – the most promising … · · 2018-01-31Lithium-ion battery technology – the most promising ... The paper discusses how rechargeable lithium-ion

Lithium-ion battery technology – the most promising

approach for exercise torpedoes

A Saft white paper

Authors:

Franck Poirier, Business Development Specialist – Saft Space & Defence Division

Louis D’Ussel, Torpedo Product Manager – Saft Space & Defence Division

About the authors

Franck Poirier is Business Development Specialist for Saft’s Space & Defence Division.

Louis D'Ussel joined Saft in France in 1980 initially as a development engineer for missile batteries

and then later for torpedoes. He moved to the US to develop Li-ion batteries for the automotive

industry (electric and hybrid vehicles).

In 2000, Louis returned to France as product manager for torpedo applications with responsibility

for sales to torpedo OEMs.

A Saft industry white paper page 2

Summary

This white paper has been produced by Saft, world specialist in the design and manufacture of high-

tech batteries, to outline the various battery technologies currently available to power electrically

propelled lightweight and heavyweight exercise torpedoes (LWTs and HWTs).

The paper discusses how rechargeable lithium-ion (Li-ion) battery technology offers significant

advantages over secondary Silver-Zinc (Ag-Zn) technology. Saft expects to see Li-ion established as

the preferred battery technology to meet the requirements of navies worldwide. Although the initial

purchase cost is currently higher than for secondary Ag-Zn batteries, the reusability of Li-ion

batteries will ensure low lifecycle costs, as each battery can be used for a much higher number of

exercises. The reduction in associated maintenance and logistic costs will also provide a

considerably more cost-effective solution.


List of contents

......................................................................................................................................................................Introduction 5

..................................................................................................................Current torpedo battery technologies 6

............................................................................................................................................Seawater-activated (primary) 6

.........................................................................................................................Silver-Zinc (primary and rechargeable) 6

......................................................................................................................................Silver-oxide aluminium (primary) 7

..................................................................................................................................................Lithium-ion (rechargeable) 7

........................................................................The current state-of-the-art for exercise torpedo batteries 8

..........................................................................................................................................Lightweight torpedoes (LWTs) 8

......................................................................................................................................Heavyweight torpedoes (HWTs) 8

.................................................................................................................................................................High sea trial costs 8

.............................................................................................................................................................Why lithium-ion? 9

....................................................................................................................Potential lithium-ion cell candidates 10

........................................................................................................................HWT – speed greater than 45 knots 11

........................................................................................................................................HWT – speed up to 45 knots 11

.........................................................................................................................................LWT – speed up to 45 knots 11

............................................................................................................Lithium-ion battery technical challenges 13

.............................................................................................................................LWT – power and energy trade-off 13

..........................................................................................................................................................HWT – safety issues 13

...............................................................................................................................................................Mechanical issues 13

..........................................................................................................................................................Voltage profile issues 13

.................................................................................................Economic advantages of lithium-ion batteries 15

...........................................................................................................Lithium-ion battery system architecture 17

..........................................................................................................................Battery management system (BMS) 17

..........................................................................................................................................Safety design considerations 18

.........................................................Future developments in rechargeable lithium battery technology 19

......................................................................................................................................................................Conclusion 20

.....................................................................................................................................................................Appendices 21

................................................................................................................................................................................About Saft 21

...................................................................................................................................................Saft torpedo experience 21

............................................................................................................................Saft underwater vehicle experience 25

Note: all photographs and illustrations used in this white paper are courtesy of Saft, except where

credited.


1 Introduction

Lightweight torpedoes (LWTs), typically 324 mm (12.75”) in diameter, are intended for anti

submarine warfare, where they are deployed from fixed or rotary wing aircraft, or from surface

vessels.

Heavyweight torpedoes (HWTs), typically 533 mm (21”) in diameter, are mainly intended for anti

surface ship warfare, and are usually launched by submarines.

During sea tests and training exercises, navies conduct a number of test firings of electrically

propelled LWT and HWT training and exercise torpedoes equipped with dummy warheads. These

torpedoes require an onboard battery system to power the electric propulsion system as well as

other electronic control and guidance circuits. The battery must provide realistic performance,

comparable to the combat version, so may be called upon to propel the torpedo at speeds over 45

knots.

The use of primary (non-rechargeable) batteries that can only be used once results in a significant

additional cost for a sea trial each time a torpedo is fired. This means there is a growing demand

for rechargeable battery systems that can be reused many times.


2 Current torpedo battery technologies

There are four main battery technologies suitable for torpedoes:

2.1 Seawater-activated (primary)

The battery is stored without electrolyte and activated by seawater

after the torpedo has been launched. A continuous flow of electrolyte is

provided through a scoop in the hull to remove the heat, gas and

mineral mud produced by the discharge and corrosion reactions.

Seawater-activated batteries have a specified storage life of a

minimum of five years when stored in their containers and protected

against humidity.

2.2 Silver-Zinc (primary and rechargeable)

Silver-zinc (Ag-Zn) cells provide the basis for making both primary and secondary (rechargeable)

batteries. In cells for primary batteries, the anode is zinc and the cathode is silver oxide. In cells for

secondary batteries, the anode is zinc oxide and the cathode is silver. In both cases, the electrolyte

is based on potassium hydroxide.

Ag-Zn batteries have a high energy and power density. In torpedo applications, rechargeable

batteries are used for exercises and primary batteries for combat.

For reasons of safety and performance, the batteries are only activated, by electrolyte injection, at

the last minute.!They can have a shelf life of over eight years.


V616 battery as used in some

A244 LWT models.

MAIT 6 HWT torpedo battery (left) and (right) Ag-Zn cells.

2.3 Silver-oxide aluminium (primary)

Silver oxide-aluminium (AgO-Al) cells feature an aluminium

anode and a silver oxide cathode. They are used to create

a Volta pile stack for underwater torpedo propulsion.

Because the sodium hydroxide electrolyte solution reacts

with the aluminium, it is prepared from sodium hydroxide

in solid form and only fed into the cell core, after being

dissolved in sea water, when the device is fired. Prior to

this, the cell is inert, and so risk-free. Because all

components, including the electrolyte, are in solid form,

prolonged storage is possible with no deterioration in

performance. !

AgO-Al batteries have high energy density and power consistent with torpedo range and speed, and

provide twice the power and energy of the standard Ag-Zn reaction at the same volume and weight.

2.4 Lithium-ion (rechargeable)

Lithium-ion (Li-ion) cell electrochemistry involves the use of lithium insertion compounds. In a Li-ion

cell, the negative electrode (anode) is graphite and the positive electrode (cathode) is a lithium-

bearing metal compound. Li-ion cells have an exceptional cycling capable due to the stable electrode

structure: charging and discharging involves exchange of lithium ions between the electrodes via

the electrolyte. Because of the high output voltage (up to 4.2 V), a non-aqueous electrolyte is used,

mainly comprising a mixture of organic carbonates.!

Various active materials can be used for the positive electrode: lithium cobalt oxide, lithium nickel

oxide, lithium aluminium oxide, lithium manganese oxide, or lithium iron phosphate. Doped nickel

oxide (NCA) offers the best cycling capability and service life for professional and defence

applications.!

Large and medium-sized Li-ion batteries have been developed in cylindrical and near-prismatic

shapes, with various energy–power trade-offs, from 150 Wh/kg with full discharge in 2 hours to

65 Wh/kg with full discharge in 15 seconds. Other notable properties of Li-ion batteries include:

• a faradic efficiency close to 100%

• sealed maintenance-free construction

• long calendar life (over 10 years at ambient temperature)

• low self-discharge (under 5% per year)

• operating temperature range from –40 °C to +60 °C

• charge level can be gauged directly by measuring voltage.


AgO-Al battery for LWT and HWT models

3 The current state-of-the-art for exercise torpedo batteries

3.1 Lightweight torpedoes (LWTs)

Currently there are no rechargeable batteries available for LWT applications. This means that a

primary cell stack is consumed for every test firing that includes a propulsion phase. A number of

demonstrators with Li-ion technology have been produced and tested worldwide. Saft developed a

demonstrator for the MU90 torpedo for DCNS, which was commercialized by EuroTorp.

3.2 Heavyweight torpedoes (HWTs)

Currently, the standard battery technology for HWT applications is rechargeable Ag-Zn. But this

technology has both a very short cycle life (12 charge/discharge cycles) and a short calendar life

(maximum of one year once wetted with electrolyte).

Even in cases where maximum speed is required (around 50 knots/93 km/h), Ag-Zn is still

suitable for DM2A4 torpedoes (as used by the German navy, for example) due to the large volume

available for the energy section. However, for the WASS/DCNS’s Black Shark, AgO-Al technology

provides a more compact energy section.

Saft has sold several cell stacks to DCNS for the F21 and the Black Shark for export markets.

3.3 High sea trial costs

For both LWTs and HWTs, the current lack of rechargeable battery systems that can offer both a

high cycle life and a long calendar life results in a considerable cost each time a test firing is carried

out.


4 Why lithium-ion?

Li-ion technology offers two main advantages for exercise torpedo applications.

First, it has one of the highest volumetric and gravimetric energy densities of all rechargeable

chemistries. So in practical terms, it can store a lot of energy/power in a compact, lightweight

package.

Second, the Li-ion electrode manufacturing process enables the design to be adapted to suit the

required power-to-energy ratio. This ranges from very thin electrodes (a few µm) for ultra-high

power applications with a power to energy ratio of 100:1, to thick electrodes for pure energy

applications with 1:1 power-to-energy ratio.

Figure 1: Comparison of battery performance for rechargeable Ag-Zn versus two types of Li-ion cell.

Figure 1 shows the power and energy density capability of bare Li-ion cells suitable for torpedo

propulsion compared with rechargeable Ag-Zn. It is possible to manufacture even more energetic

cells, but they lack power capability, while more powerful cells will lack energy content.


5 Potential lithium-ion cell candidates

Saft has been working on the development of Li-ion battery systems for exercise torpedoes since

early 2000, when initial prototypes proved the capability to provide over 100 charge/discharge

cycles for both LWT and HWT configurations. By 2005 the project had resulted in a demonstration

battery for LWT torpedoes.

Figure 2: Saft Li-ion cell range.

The Saft demonstration systems are based on the company’s VL range of cylindrical Li-ion cells,

which include the latest developments in cell design, housing, connections and electronic devices

for safety, cycle and calendar life, reliability and cost. These cells are available in high energy VLE,

medium range VLM, high power VLP and very high power VLV versions and, as shown in Figures 2

and 3, the choice of cell for a specific application involves a trade-off between energy and power.


Torpedo Li-ion battery system demonstrators for LWT & HWT models (developed with

DCNS).

! VL45E VL41M VL22M VL30P VL7P

Specific energy [Wh/kg] 149 136 120 97 67

Energy density [Wh/L] 313 285 236 209 131

Specific power [W/kg] 664 794 1076 1136 1811

Power density [W/L] 1392 1667 2121 2451 3526

Density [kg/L] 2.10 2.10 1.9 2,15 1,96

Power-to-energy [W/Wh] 4.4 5,8 8.8 11.7 26.9

Figure 3: Power-to-energy ratio and density for a range of Saft cylindrical industrial Li-ion cells, from

the high-energy VL45E to the high-power VL7P.

The trade-off between energy and power is best illustrated by considering some typical application

scenarios.

5.1 HWT – speed greater than 45 knots

If an HWT torpedo is required to achieve a speed in excess of 45 knots, it will need a battery

capable of delivering over 250 kW. A suitable cell would be in the medium range of the energy–

power spectrum, such as the VL30P (30 Ah) or VL41M (41 Ah), depending on the available volume

for the energy section.

5.2 HWT – speed up to 45 knots

If the maximum speed of the HWT torpedo is slightly reduced, to 45 knots or less, it will need a

battery of less than 200 kW. So a VL41M (41 Ah) cell could be used.

5.3 LWT – speed up to 45 knots

Propulsion of an LWT at speeds up to 45 knots calls for a 90 kW battery, so either the VL6P (6

Ah) or VL12V (12 Ah) cells might be suitable.


Saft cylindrical Li-ion cells.


6 Lithium-ion battery technical challenges

There are a number of key technical challenges that must be addressed in the design and

development of a Li-ion torpedo battery system:

6.1 LWT – power and energy trade-off

The trade-off between power and energy requirements when considering rechargeable battery

solutions for an LWT exercise torpedo is challenging, since today’s seawater and AgO-Al energy

section are very compact. So it is impossible to achieve the same power (speed) and energy (range)

capabilities with rechargeable technology as it is with one-off combat batteries. So a trade-off has to

be made between power and energy. For LWT torpedoes in particular, there is a major challenge

in providing a battery that makes optimum use of the restricted space available, while meeting

maximum speed requirements with the required level of endurance.

6.2 HWT – safety issues

Safety is an especially critical issue for HWT torpedoes as they are generally launched from

submarines.

Battery systems must be protected against external abuses and internal failures. External abuses

include shocks, fire, short-circuit, overcharge and water immersion (such as when water enters the

torpedo tube). Internal failures could be short-circuit, individual cell failure (for example, from venting

or fire). In the event of a venting fire, the battery must be designed to ensure the non-contamination

of both the other cells and the whole battery compartment.

6.3 Mechanical issues

LWT torpedo batteries need to cope with the shock of entry into seawater, while HWT torpedo

batteries must withstand firing loads.

6.4 Voltage profile issues

One advantage of Ag-Zn batteries is that they offer a much flatter discharge voltage profile than Li-

ion batteries. This means that Li-ion technology is not backward-compatible with older torpedoes

(such as SUT/SST4, Tigerfish, F17 and A184) that use direct-driven DC motors. A DC motor acts

as a constant resistance, so that when the voltage is flat the power is constant, but when the

voltage decreases with depth of discharge (DOD) the power decreases too. However, Li-ion

technology is ideal for use with newer torpedoes that have DC–DC converters driving DC motors or

asynchronous motors (such as MU90, DM2A4, F21 and Black Shark), because the system is able

to compensate for the voltage drop by drawing more current in order to maintain constant speed.


Figure 4: Typical discharge profile of Ag-Zn vs Ni-based Li-ion technology.


7 Economic advantages of lithium-ion batteries

A key advantage of Li-ion batteries for exercise torpedoes is their low life-cycle cost, thanks to their

ability to be reused many times over. This means that, unlike with primary Ag-Zn batteries, there is

a payback period that starts the second time the torpedo is fired.

Figure 5: Relative costs of Li-ion (red line) vs Ag-Zn (blue line).

In comparison with secondary (rechargeable) Ag-Zn batteries a Li-ion battery is, at the current

state of the market, slightly more expensive. However, Ag-Zn batteries can only provide 10 charge/

discharge cycles within a period of 12 months from first use, while Li-ion can support over 50

cycles over an extended lifetime – so the total cost of ownership (TCO) advantages are clear. In

both cases, Li-ion technology will provide a much more cost-effective way to perform sea trials.

Figure 5 illustrates a typical TCO scenario. With Ag-Zn rechargeable battery technology, the navy

needs to buy a complete battery system in the first year, which comprises a battery tray and

auxiliary components, the cells and the silver metal. A new set of cells must be purchased every

year: the battery tray is reusable and the silver metal is recovered from the old set of cells to be

used in the new set.

By comparison, using Li-Ion battery technology, the navy would need to buy a complete system in

the first year, but no additional expense is incurred throughout the life of the battery.

A further advantage of Li-ion cells is that they are sealed for life and totally maintenance-free. Their

condition can be monitored simply and effectively via the integral battery management system

(BMS). This dramatically reduces torpedo maintenance costs. By contrast, maintenance for Ag-Zn

involves removal of the battery from the torpedo hull and then disassembly of the battery itself for

electrolyte topping, connection cleaning and recharging – a process that can take up to seven days.


The sealed design of Li-ion cells can also simplify the battery system design process, compared with

Ag-Zn technology, as it offers the flexibility for horizontal or vertical mounting as required, making

optimum use of the available space. This provides a further advantage for users during the handling

of the torpedo as the actual positions of the cells is less critical.


8 Lithium-ion battery system architecture

Saft takes into account all the various technical challenges in delivering a safe Li-ion battery solution,

by implementing several levels of protection against internal and external factors:

• Cell level (electrochemistry, shutdown separator, etc.)

• Electronic level (battery monitoring systems, battery protection circuit)

• System level (mechanical design).

Safety systems must be a coordinated solution tailored to the customer’s requirements.

8.1 Battery management system (BMS)

The BMS incorporated in the battery compartment communicates with the torpedo EGB via a data

bus. It provides key information relating to the battery status, such as available power and energy

remaining, and sends alerts about external or internal events. This gives the naval operator

improved visibility of the torpedo’s state of health, ensuring more accurate logistical planning and

greater mission efficiency.

When constructing a Li-ion battery it is recommended that cells are placed in parallel strings (to

develop the required capacity) and then connected in series to achieve the required voltage. This

reduces the overall cost, as a single BMS can be used; otherwise a BMS is needed for each parallel

string.

In Saft Li-ion batteries, each parallel cell group is connected with a Gemplus electronics card that

provides:

• 16 A/D channels

• voltage and temperature measurement

• cell balancing

• voltage redundant threshold detection

• communication with the BMS.

Each Gemplus card then connects to the BMS, which provides:

• current measurement

• battery management algorithms

• communication with the charger

• communication with the torpedo.


8.2 Safety design considerations

Li-ion cells are sensitive to overcharge and over-discharge, operating temperatures above the

recommended range, and short circuit. The effect of any of these conditions depends on the cell’s

state of charge – the main issue is the flammability of the electrolyte.

For protection against overcharge, the battery and individual cells must be protected by a

redundant electronic system based on voltage measurement.

An electronic system is also required to protect the battery and cells against over-discharge. This

will cause an over-discharged cell to end up in a short circuit condition, but there is no risk attached

to this as it is already discharged.

Only a very low-impedance short-circuit may damage the battery, resulting in overheating. So

battery short circuit protection is provided by a fuse.

The only protection against mechanical damage to individual cells such as from bullets or shrapnel

is the torpedo casing. It is desirable therefore to insulate individual cells to avoid cross-

contamination (the avalanche effect) in case of fire or overheating. This can be achieved by placing

cells in insulated tubes. This only increases weight slightly while significantly improving safety.

The whole battery system must be protected against the ingress of seawater.


9 Future developments in rechargeable lithium battery

technology

As mentioned earlier, Li-ion (Ni-based cathode) technology is suitable only for DC–DC converter-

controlled motors or asynchronous motors. So for direct-drive DC motors, another rechargeable

solution might be considered, such as lithium iron phosphate technology (LiFePO4, sometimes

known as LFP). In fact, since it provides a flat voltage profile during discharge, LiFePO4 enables its

speed to be maintained when directly connected to the DC motor.

LiFePO4 cells also offer increased safety at the electrochemistry level – in particular they have good

thermal stability that can limit the effects of severe abuse.

Saft has developed two LiFePO4 cells for power and very high power military applications – VL10Fe

and VL25Fe. Energy cells using this chemistry are under development.

Saft VL25Fe and VL10Fe LiFePO4 cells.

LiFePO4 technology is, however, still evolving and has not yet solved the challenge of calendar life at

elevated temperature. However, navies have less need for storage at higher temperatures than

many other users, especially when it comes to torpedoes. There are also some practical challenges

to overcome, specifically in developing an optimized capacity gauge and in balancing cell-to-cell

capacity. Today’s techniques, such as coulomb counting or more traditional resistive balancing, do

work very well either at high or low states of charge. Currently, LiFePO4 offers slightly lower energy

density than nickel-based Li-ion, for either LWT or HWT applications. At the same time, LiFePO4

offers higher abuse tolerance, and it is the customer who must decide on the trade-off between

these two parameters.


10 Conclusion

As things stand today, rechargeable Li-ion battery systems represent the most promising solution

for both LWT and HWT torpedoes when performance, calendar life and TCO are taken into

consideration.

Navies throughout the world are placing an ever increasing emphasis on achieving optimum TCO

for their exercise torpedo batteries. Li-ion battery technology enables them to address this issue by

offering:

• Low life-cycle costs through increased reusability

• Performance comparable to combat torpedoes

• Long service life

• Long calendar life

• Safe operation and ease of handling

• Reduced maintenance and logistic costs.


11 Appendices

11.1 About Saft

Saft is a global, multi-technology battery specialist and is the world’s leading manufacturer of high-

end batteries for industrial, transportation, space and defence applications.

The company operates at the forefront of innovation, developing and delivering advanced solutions

for critical applications that are highly dependent upon integrated technology. As the next

generation of intelligent defence systems takes shape, Saft is actively engaged in supporting major

international companies leading this change.

11.2 Saft torpedo experience

11.2.1 Battery contracts for the German, Norwegian and Korean navies

In 2006 Saft was awarded three major new contracts for Ag-Zn torpedo batteries for the German,

Norwegian and South Korean navies. The contracts, fulfilled by Saft’s specialized production facility

in Poitiers, France, include: rechargeable batteries for the German navy’s DM2A3 and DM2A4

training exercise torpedoes; primary batteries for the Norwegian navy’s DM2A3 combat torpedoes;

and reserve batteries for the South Korean navy’s SUT combat torpedoes.

11.2.2 German navy training exercise batteries

In summer 2005, Saft completed the German navy’s qualification procedures to become a

qualified, recognized supplier of Ag-Zn rechargeable batteries based on its type 120 SHV cells.

These batteries are used as training exercise batteries in the DM2A3 torpedo, with active wire

guidance homing, manufactured by ATLAS Electronik Gmbh, as well as in the latest version of the

fiber-optic guided DM2A4 torpedo.

Immediately following the qualification process, the German navy had an urgent requirement for

1044 Ag-Zn cells to be delivered before the end of the year. Saft won the competitive tender with

its 120 SHV cells and the contract was agreed in October 2005. Thanks to its dedicated

production facilities in Poitiers, Saft was able to respond to this demanding manufacturing schedule

and delivered the cells on time.

The 120 SHV Ag-Zn cell has a 120 Ah capacity and a nominal voltage of 1.5 V, and is designed

according to the German Military Standard VG 95 284-120. The German Military’s qualification

process has confirmed the successful completion of production of this cell by Saft in Poitiers. The

same cells are also used worldwide for the exercise batteries of the SST4/SUT and the MK 24

(Tigerfish) torpedo systems.


11.2.3 Norwegian navy combat torpedo batteries

In July 2005, the Norwegian navy entered into a framework agreement with Saft to deliver up to

15 Ag-Zn combat batteries a year to the MTV 6135-206 specification for the heavyweight DM2A3

torpedo. The framework agreement is for a period of three years, with an option to extend.

Qualification tests on this battery type, to verify its production by Saft in Poitiers, were carried out by

the German BWB in cooperation with the Norwegian and German Navies. After delivering test

batteries in 2005, Saft achieved qualification in 2006.

The Saft DM2A3 combat battery is a very compact, remotely activated primary battery, with the

latest safety features. Even in the event of an unintended activation, the battery will discharge itself

safely to avoid any security issues. This provides additional safety for staff when the battery (inside a

torpedo) is handled or stored onboard a submarine.

The DM2A3 battery is the most advanced in Saft’s range of combat batteries, which also includes

batteries for the SST4/SUT torpedoes manufactured by ATLAS Elektronik GmbH.

11.2.4 Technology transfer contract in South Korea

Saft has implemented a licensing agreement with Sebang Hi Tech of South Korea for type PB47

reserve Ag-Zn batteries for the SUT heavyweight combat torpedo. Under the terms of the

agreement, signed in 1998, Saft is providing the key components to enable Sebang Hi Tech to

manufacture and deliver SUT type combat torpedoes to the South Korean Navy. The six-year

contract also includes a retrofitting element.

Saft PB47 torpedo battery.

The PB47 battery is certified by ATLAS Elektronik Gmbh to power the propulsion and electronic

systems of the SST4/SUT torpedoes. The battery is activated by a pyrotechnic device, ignited by an

external electrical signal.


Saft PB47 batteries are being used successfully by several navies worldwide, especially in Asia,

South America and Europe.

In implementing this licensing agreement with Sebang Hi Tech, Saft is consolidating a long

partnership in South Korea that started with the same company in 1992, with a licensing

agreement for BSO technology.

11.2.5 Contract for the Australian navy’s EuroTorp lightweight MU90 torpedoes

Saft has been awarded a multi-million Euro contract by DCNS, the French naval defence systems

group, to supply Al-AgO seawater-activated propulsion batteries for the EuroTorp lightweight MU90

torpedoes currently being produced for a number of NATO navies.

The MU90 is a new generation torpedo designed to combat modern, deep-diving submarines

carrying advanced countermeasures, and Saft’s unique Al-AgO battery technology makes a major

contribution to its exceptional speed and agility by delivering the optimum combination of high

power and excellent endurance.

MU90 torpedo (EuroTorp).

The project for the Australian navy is EuroTorp’s latest export contract for the MU90 torpedo.

Winning the contract for the battery systems consolidated Saft’s position as a major supplier to the

torpedo market contract, and follows previous orders from DCNS for MU90 propulsion batteries

for the French navy, as well as similar orders for batteries for the Black Shark heavyweight

torpedoes for the navies of Chile, Malaysia and Portugal.


EuroTorp has designed the MU90 to be fast and agile, while ensuring range and diving capabilities

comparable to those of current-generation heavyweight torpedoes. Its skewed multi-blade electric

pump-jet propulsor is powered by a Saft Al-AgO battery, capable of delivering twice as much energy

and power as conventional Ag-Zn batteries of the same mass and volume. The Al-AgO technology,

which is unique to Saft, also has the advantage of a maintenance-free storage life of up to 12 years.

MU90 torpedo (EuroTorp)

The Saft battery provides the MU90 with extremely long endurance, and it is capable of operating

without any degradation in water depths in excess of 1,000 m and as shallow as 25 m, while

retaining navigation capability in water depths as low as 3 m.

Other navies that use the MU90 include those of Denmark, France, Germany, Italy and Poland.

11.2.6 Contract to power Black Shark heavyweight torpedoes

Saft was awarded a major contract by DCNS to supply advanced battery systems based on its

unique Al-AgO technology to power Black Shark heavyweight torpedoes. DCNS will assemble the

Saft Al-AgO batteries, capable of delivering twice as much energy and power as conventional Ag-Zn

batteries, into PB50 torpedo electric propulsion systems for use in the construction of Black Shark

torpedoes for the navies of Chile, Malaysia and Portugal.

The Black Shark advanced dual-purpose, long-range, wire guided and self-homing torpedo is, from a

propulsion point of view, a heavyweight version of the EuroTorp MU90/IMPACT lightweight torpedo

that already uses a Saft Al-AgO battery system. The battery powers an electric propulsion system,

comprising an electronically controlled high-RPM brushless motor, driving a skewed, multi-blade,

pump-jet propulsor, capable of propelling the 6.3 m long, 0.53 m diameter torpedo at speeds in the

region of 50 knots for more than 10 minutes. The battery also powers the onboard electronic

control, guidance and countermeasures systems.


11.2.7 Aluminium-silver oxide battery technology

At the end of the 1980s, the JFP programme between France, Germany and Italy was set up to

define a new electric propulsion system for HWTs, and Al-AgO was the selected technology. This is

because, for the same mass and volume, an Al-AgO battery can deliver twice as much energy and

power as a conventional Ag-Zn battery. Furthermore, Al-AgO has a maintenance-free storage life of

up to 12 years. Currently, Saft is the only battery manufacturer able to offer Al-AgO technology.

The Black Shark battery system is an upgraded version of the MU90 battery system. It is activated

by seawater, uses dissolved sodium-dioxide powder as the electrolyte, and incorporates an

advanced closed-loop electrolyte recirculation system.

11.3 Saft underwater vehicle experience

Saft has vast experience in supplying battery systems for autonomous, unmanned and swimmer

delivery vehicles (AUV/UUV/SDV).

11.3.1 New French navy Autonomous Underwater Vehicle (AUV)

Saft has won a contract from ECA, the France-based robotic systems specialist, to supply the Li-ion

battery system that will power the French Navy’s ‘Guerre des Mines’ mine countermeasures

Autonomous Underwater Vehicle (AUV) currently under development. The advanced technology

Saft Li-ion battery system will enable the new demonstrator AUV to stay submerged for a long

period of time while cruising at 4 knots (7.4 km/h). Li-ion is the only battery technology capable of

providing this combination of endurance and power in the restricted space available within the

AUV’s design.

Daurade AUV (ECA).


This new order for the ‘Guerre des Mines’ AUV follows the success of the Li-ion battery systems

that Saft has supplied previously for GESMA’s Redermor-3 experimental Unmanned Underwater

Vehicle (UUV) platform and ECA’s Daurade AUV.

The 135 V, 23 kWh battery system, which is identical to the battery installed on Daurade, will

power the propulsion and electronics systems on ‘Guerre des Mines’. It is based on Saft MP

176065 Li-ion cells, and Saft is supplying it as a fully integrated, turnkey system, including

mechanical assembly, an electronic control management system for the monitoring of charge and

discharge voltages and cell temperatures, and EMC filtering.

11.3.2 Li-ion battery power for BAe Systems’ Talisman autonomous underwater vehicle

Saft has been chosen by BAe Systems to supply Li-ion batteries for its Talisman ‘M’ AUV. The

vehicle was unveiled in 2007 and is designed to meet the growing demand from navies for

independent vehicles that can undertake a variety of often dangerous tasks, including dealing with

mines.

Talisman AUV (BAe Systems).

Talisman ‘M’ is approximately 4.5 m long by 1.7 m wide, weighs around 1,000 kg, can carry

payloads of 500 kg or more and can operate at depths of up to 300 m. Propulsion and manoeuvre

control is provided by four Seaeye SMS ducted-fan thrusters which drive it at speeds of up to 5

knots. The thrusters enable it to hover, move vertically and turn in its own length. The vehicle is

designed to operate with a high degree of accuracy throughout its autonomous missions.


In its basic configuration, Saft’s Li-ion power system can deliver up to 24 hours of continuous

operation to the Talisman. In a recent development, the batteries can be recharged on the surface

by an integral miniature 3hp diesel engine, extending its range and performance significantly.

11.3.3 Li-ion battery system for GESMA Redermor

Saft was awarded a contract by Groupe d’Etudes Sous Marines de l’Atlantique (GESMA) to develop

the rechargeable Li-ion battery system to provide a significant boost to the performance and

payload capacity of the Redermor experimental UUV platform. The new Li-ion battery system

provides Redermor with up to five hours of autonomous power for the UUV’s electric thrusters and

onboard electronics. Housed in a compact, maintenance-free module, the new Li-ion battery system

is just half the size of the previous Redermor battery system.

Redermor UUV (GESMA).

Redermor’s power is drawn from a 260 V onboard battery. When designing the new version, the

Redermor-3, GESMA selected Saft’s Li-ion technology in order to drastically reduce the size of the

battery while maintaining the same performance as the current battery system. GESMA also

required an easy-to-operate and maintenance-free subsystem. The reduced size enables the

operator to increase the equipment payload or to add another high-power battery pack to

effectively double its endurance.


For more information, please contact:

franck.poirier @saftbatteries.com

Saft

12 Rue Sadi Carnot

93170 Bagnolet – France

Tel: +33 149 931 780 Fax: +33 149 931 969

www.saftbatteries.com

Saft torpedo battery white paper – March 2009


http://www.saftbatteries.com

mailto:[email protected]?subject=Saft%20torpedo%20battery%20white%20paper

mailto:[email protected]?subject=Saft%20torpedo%20battery%20white%20paper

http://www.saftbatteries.com

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