DRDO’s Advanced Light-Weight Torpedo (ALWT) to Receive Speed Bump by 42% – Indian Defence Research Wing
Advanced Light-Weight Torpedo (ALWT)
Advanced Light-Weight Torpedo (ALWT) is the 2nd generation of Shyena anti-submarine torpedo. The torpedo is developed by Naval Science and Technological Laboratory (NSTL) of DRDO and produced by Bharat Electronics Limited (BEL). It can be launched from ship, helicopter or from a fixed wing aircraft. The torpedo boasts a dual-speed capability for which it has a range of 25 km (16 mi) at 25 kn (46 km/h) and a range of 12 km (7.5 mi) at 50 kn (93 km/h). It uses sea-water powered battery which eliminates the requirement of pre-launch charging. On 17 July 2024, it was announced that ALWT has completed all the user trials and is poised to replace Mark 46 torpedo in the Indian Navy's inventory. The torpedo will also be integrated on the Boeing P-8I Neptune fleet of the Indian Navy for anti-submarine warfare operations.[11][12][13]
Summary
Speed & Power Upgrades:
- Getting a new 100 kW Magnesium-Silver Chloride (Mg-AgCl) battery
- Speed increasing from 33 knots to 47 knots (a 42% improvement)
- This makes it more effective against fast-moving submarines by reducing their escape window
Current Operational Capabilities:
- Dual-speed operation:
- 25 km range at 25 knots (46 km/h)
- 12 km range at 50 knots (93 km/h)
- Uses sea-water powered battery (no pre-launch charging needed)
- Can be launched from multiple platforms:
- Ships
- Helicopters
- Fixed-wing aircraft
- Will be integrated with Boeing P-8I Neptune fleet
Status:
- Has completed all user trials
- Set to replace Mark 46 torpedo in Indian Navy's inventory
- Already being exported (first batch sent to Myanmar as part of $37.9M deal)
- Manufactured by Bharat Electronics Limited (BEL)
This second-generation torpedo represents a significant advancement in India's indigenous defense capabilities, particularly in anti-submarine warfare operations.
Battery
Key Battery Characteristics:
- Uses magnesium anode and silver chloride cathode
- Activated by seawater (no pre-charging needed)
- Single-use batteries that typically run for minutes to hours
- Power density: 100-150 Wh/kg (comparable to lithium-ion)
- Performance varies with water temperature and salinity
ALWT's Updated Capabilities:
- New 100 kW Mg-AgCl battery upgrade
- Top Speed increase from 33 to 47 knots (42% improvement)
Advantages of Water-Activated Design:
- Can be stored dry for years without degradation
- Forced-flow design uses torpedo's motion to:
- Continuously refresh electrolyte
- Provide cooling
- Maintain stable performance
- Ideal for maritime applications where water is readily available
Operational Flexibility:
- Multiple launch platforms: ships, helicopters, aircraft
- Will integrate with P-8I Neptune fleet
- Completed user trials
- Set to replace Mark 46 torpedo
- Already in export (Myanmar deal worth $37.9M)
For comparison, a similar torpedo system (A244) uses a 146-cell Mg-AgCl battery that:
- Delivers 32 kW at 160V nominal
- Operates for 6 minutes
- Functions in water temperatures 0°C to 30°C
- Requires salinity between 15-38g/l
- Voltage ranges from 190V peak to 140V cutoff
The upgrade represents a significant advancement in India's indigenous torpedo capabilities, particularly in anti-submarine warfare operations where speed and power are crucial for target interception.
Competition
Confirmed Systems:
1. A244 torpedo series (mod 0, mod 1, mod S)
- Manufacturer: Whitehead Alenia Systemi Subacquei
- Battery: V616 by Saft
- Used by 14 different navies across South America, Asia, Southern and Northern Europe
2. Sting Ray Mod 1 (BAE Systems)
- Used by UK MOD and Norwegian Armed Forces
- Uses Mg-AgCl battery with seawater electrolyte
- Features improved battery stack manufacturing and installation
3. USN Mark 44 torpedo (Historical)
- Used Mg-AgCl battery for propulsion and seeker systems
- Mentioned as an early post-WWII implementation
- Has since been phased out
Battery Vendors Mentioned:
- Saft (confirmed manufacturer for A244 torpedoes)
- Described as "sole qualified supplier" for V616 battery used in A244
The documentation primarily focuses on these specific systems, though it suggests there are other modern implementations that have replaced the older Mark 44 style systems. Without additional documentation, I cannot make claims about other specific torpedoes or vendors using this technology.
Mg-Ag-Cl NaCl+H2O Activated Batteries
Core Operating Principles:
- Uses solid-state components:
- Magnesium anode
- Silver chloride cathode
- Separated by porous, absorbent membranes
- Activated when seawater acts as electrolyte
- Can be configured as "dunk" or "forced-flow" designs
Advantages:
1. Storage & Shelf Life
- Can be stored completely dry
- Years of shelf life without degradation
- Only requires desiccant in sealed package
- No self-discharge when stored (unlike conventional batteries)
2. Performance
- High power density (100-150 Wh/kg)
- Comparable to lithium-ion (100-265 Wh/kg)
- Can deliver high power (tens to hundreds of kilowatts)
- Forced-flow design allows continuous electrolyte replacement
- Self-cooling through water flow
- Can work in cold conditions (heat from reaction prevents freezing)
3. Operational
- Readily available electrolyte in maritime applications
- No pre-charging required
- Simple activation process
- Environmentally friendly (no heavy metals) for disposable applications
Disadvantages:
1. Performance Limitations
- Single-use only
- Short runtime (typically minutes to hours)
- High self-discharge when activated
- Performance varies with:
- Water temperature (0°C to 30°C operating range)
- Salinity requirements (15-38g/l for optimal performance)
2. Operational Constraints
- Requires continuous water contact
- Electrolyte can boil off or freeze in extreme conditions
- Needs water flow for high-performance applications
- "Messy" compared to conventional batteries for regular use
Alternative Options:
- Cheaper versions available using:
- Copper chloride cathodes
- Lead chloride cathodes
- Lower power density (50-80 Wh/kg)
- Can't match silver chloride versions' current output
- Voltage range: 1.0-1.7V per cell
Primary Applications:
- Military torpedoes
- Emergency maritime equipment
- Radiosondes
- Sonobuoys
- Life jacket emergency lights
- Emergency radio beacons
- Smart pills (microscale versions)
This battery technology fills a specific niche where long shelf life, high power, and underwater operation are crucial, despite its limitations as a single-use system with environmental constraints.
Defence Make In India: First Batch Of Lightweight Anti-Submarine Shyena Torpedoes Sent To Myanmar
In a milestone achievement for the Indian arms industry, the first batch of Advanced Light Torpedo (TAL) Shyena torpedoes have been sent to Myanmar as part of an export deal worth $37.9 million which was signed in 2017, reports Livefist.
The torpedoes were manufactured by Bharat Dynamics Limited (BDL), which is a public sector enterprise. Larsen & Toubro was behind the integration of the torpedoes with launcher systems.
TAL Shyena is India’s first domestically produced lightweight anti-submarine torpedo, and it was developed by DRDO’s Naval Science and Technological Laboratory. BDL manufacturers the the torpedoes at its facility in Visakhapatnam.
The supply of Shyena torpedos speaks to the growing ties between India and Myanmar, with the former also previously having supplied the latter with acoustic drones, naval sonars and other military equipment.
The two countries have also reportedly stepped up cooperation in their borden regions to flush out separatist ethnic militants.
SOURCE: IDRW.ORG.
India’s Defence Research and Development Organisation (DRDO) is set to elevate the capabilities of the Advanced Light-Weight Torpedo (ALWT) with a 100 kW Magnesium-Silver Chloride (Mg-AgCl) battery upgrade, intended to boost its speed from 33 knots to an impressive 47 knots—a significant 42% increase. This enhancement aims to meet evolving anti-submarine warfare (ASW) requirements for the Indian Navy, furthering India’s indigenous defense technology capabilities.
The ALWT is the second generation of the Shyena torpedo, developed by DRDO’s Naval Science and Technological Laboratory (NSTL), with production managed by Bharat Electronics Limited (BEL). Specifically designed for anti-submarine warfare, the ALWT has cleared all trials and has been proposed for production.
The current ALWT operates at a speed of 33 knots, which allows it to engage submarines effectively in various underwater conditions. However, DRDO’s planned battery enhancement—procuring a 100 kW Mg-AgCl battery—will raise the torpedo’s speed to 47 knots, marking a 42% increase in speed.
The increase in speed enables the ALWT to catch fast-moving submarines more effectively. Submarines capable of evading torpedoes rely heavily on speed and maneuverability; a 47-knot torpedo will minimize their escape window. Higher speed shortens the time needed for the torpedo to close in on a target, thereby reducing the likelihood of countermeasures by enemy submarines.
The increase in speed enhances the effective range over time, allowing the torpedo to cover more distance quickly, making it suitable for varied deployment scenarios in deeper and broader areas of the Indian Ocean Region.
The 100 kW Mg-AgCl battery is pivotal in achieving this upgrade, as its power density and reliability make it well-suited for underwater systems that demand both high speed and endurance. The Mg-AgCl battery offers high power output with an excellent energy-to-weight ratio, making it ideal for the ALWT’s size and operational requirements. This advanced battery chemistry ensures that the ALWT can sustain high-speed pursuits while maintaining performance integrity throughout the mission.
Thank Magnesium For Water-Activated Batteries
Most of the batteries we use these days, whether rechargeable or not, are generally self-contained affairs. They come in a sealed package, with the anode, cathode, and electrolyte all wrapped up inside a stout plastic or metal casing. All the reactive chemicals stay inside.
However, a certain class of magnesium batteries are manufactured in a dry, unreactive state. To switch these batteries on, all you need to do is add water! Let’s take a look at these useful devices, and explore some of their applications.
Just Add Water
Magnesium water-activated batteries come in a variety of types and formats, but the various styles available all share some common attributes. They all use a magnesium anode, and rely on aqueous solutions as the electrolyte. Typical selections involve fresh water or seawater, though custom preparations can be used to vary the battery’s performance characteristics.
The main benefit of these batteries is that they can be produced in an entirely “dry” fashion. The magnesium anode and the various salt cathodes used are all solid-state materials. Without the water electrolyte in place, they can happily sit on the shelf for years without degrading. That’s a big benefit over the traditional batteries we use every day, which start the self-discharge process as soon as they’re manufactured. Magnesium batteries inherently have high self-discharge, too, but without the electrolyte in place, the battery isn’t complete, and it simply doesn’t happen. However, this does mean they’re single-use batteries that typically run for minutes to hours at the most.
The batteries are available in a range of chemistries, with magnesium-silver chloride batteries the best choice for performance applications. In practice, they typically offer power densities of up to 100 to 150 Wh/kg, on a par with lithium ion batteries, which can deliver 100 to 265 Wh/kg. Alternative chemistries are often chosen for their lower cost, with copper chloride and lead chloride among the more commonly used. Cells built with these cathode materials are much cheaper thanks to the lack of silver content, but can’t deliver the same power. Typically, they come in around 50 to 80 Wh/kg, and can’t deliver the same current as silver chloride-based cells. Depending on the chemistry, open-circuit voltages range from approximately 1.0 to 1.7 V, with higher voltages achieved by stacking many cells together.
Different Configurations
Water can be added to the battery in a variety of ways, depending on the desired application. So-called “dunk” batteries have the anodes and cathodes separated by porous, absorbent membranes. They can simply be dunked in a bucket of water to activate them, or filled with water manually, and typically run for several hours. Dunk batteries are often used on radiosondes and other equipment that benefits from a battery design with great shelf life and no heavy metal content, as they often end up left in the environment.
They’re generally stored in hermetically-sealed packs with a dessicant for good measure. When needed, the pack can be opened, and the battery juiced up, and it’s ready to go. They’ll run as long as the electrolyte is present or the cathode and andoe have ions left to give.
When used in extreme conditions, the electrolyte can boil off or freeze, and the battery will cease to deliver electricity. However, the heat generated from the battery’s own chemical reaction can sometimes provide enough heat to stave off freezing, making these batteries capable in low temperature conditions.
Immersion batteries are intended for use fully-submerged, as their name implies. Applications typically involve equipment for maritime emergencies. In these roles, the long stable shelf-life pays off, and there’s typically abundant water around to serve as an electrolyte. They’re commonly used to power emergency lights on life jackets carried in airliners, with a small quantity of salt often included in the battery to enable good performance even if the wearer lands in a freshwater lake. Other uses include power for radios and beacons on lifeboats, as well as sonobuoys, which spend their working life underwater.
The highest-performance water-activated batteries are of the forced-flow type, primarily used to power propulsion and electronics in torpedos. These take advantage of the fact that the torpedo’s forward motion can force fresh salt water through the battery, continually replenishing the electrolyte. This also serves to cool the battery, keeping it at a stable temperature for best performance.
Forced-flow magnesium-silver chloride batteries have been built in configurations of hundreds of cells in series, delivering tens to hundreds of kilowatts of power. Run times are typically on the order of 5-15 minutes, which is usually more than long enough for a torpedo to find its target and explode. These batteries took off in earnest in the wake of World War II, though have slowly been phased out by other solutions in more modern hardware.
Other obscure uses exist for these batteries, too. Smart pills exist that feature a tiny magnesium-copper cell inside. Upon coming into contact with stomach acid, the cell begins to provide electricity to a tiny circuit that sends a radio message indicating the pill has begun digestion. The cell itself is digested like any other minerals in the stomach, and the transmitter circuit is passed out of the body as waste.
Fit For Purpose
These batteries aren’t something that most of us would use on a daily basis. Their method of activation is comparatively messy compared to conventional batteries, and most of us don’t need a battery to maintain peak performance after sitting on a shelf for five or ten years. However, in a wide range of scientific, military, and industrial contexts, they’re incredibly useful. In these contexts, where it’s important to have a battery that’s ready to go at the drop of a hat after sitting for a long time, it’s hard to argue with the capability of magnesium water-activated batteries.
Headline photo: “Close-up Photo of Batteries” by Hilary Halliwell. Thumbnail image: “dead batteries” by John Seb Barber
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