High energy, low weight: the challenge for modern soldiers
The weight a soldier carries is a serious issue. Carrying heavy equipment for long periods makes a soldier less mobile, increases fatigue and raises the risk of injury. And as their gear gets more hi-tech, they must carry batteries to power it all.
In 2001, the US Army Science Board recommended that no soldier carry more than 22 kg of equipment, including body armor, weapons and batteries. However, the average US soldier in Iraq and Afghanistan was routinely carrying 27-45 kg – often in oppressive heat.
British soldiers in Afghanistan carried even heavier loads, according to Jane’s Defence; their equipment could weigh as much as 63 kg – more than double that carried by their predecessors in the Falklands War in the early 1980s. Many soldiers returning from combat tours suffer from back problems, muscular and bone injuries, and arthritis.
Aside from weaponry, protective gear and any special equipment they might need for their mission, everything a soldier carries is there to answer one or more of four questions: Where am I? Where are my friends? Where are my enemies? And what is my mission?
That means carrying a GPS device and maps – usually on a rugged tablet computer – as well as short-range radios, satellite phones for long-range communication, night-vision gear, chemical detectors and assorted sensors, some of which will be left in the field to track enemy movement.
Powering all that means carrying batteries, which add weight. When assessing the weight of a battery, militaries look for the greatest watt hours per kilogram (Wh/kg) that they can afford.
Soldiers often carry several batteries, because while some devices can share one, plenty cannot. Militaries, like other modern organizations, must cope with legacy technology. Each device a soldier carries might have been added to the kit at a different time and require a battery that is not compatible with the rest of it.
A new piece of equipment added to the rifle might need its own battery, which means modifying the weapon or running a cable from the rifle to a battery carried by the soldier. This could be a multi-purpose battery such as the BB-2590, which was designed more than 40 years ago to power a manpack radio and now has more than 50 different uses.
The rechargeable battery chemistry in the BB-2590 has evolved from its original lead-acid configuration, through nickel-based to its current lithium-ion (Li-ion) chemistry. Although what’s inside the battery has changed, today’s model will still power the same radio that it powered in the 1970s.
Battery manufacturers like Saft try to do their part to lighten a soldier’s load by developing new designs, chemistries and materials. Saft’s most recent version of the BB-2590, for example, the BB-2590HC/U, offers 187 Wh/kg, compared with its predecessor’s 127 Wh/kg.
The requirements for batteries carried by soldiers are numerous and exacting. They must be able to withstand the vibration from gunfire as well as from the various vehicles the soldier might travel in. They need to cope with drops, shocks, radiation, extreme temperatures, sand, dust, fungus, mold and immersion in water – up to 30 meters for Navy SEALS.
Most militaries are carrying out modernization programs that give soldiers the latest technology, consolidate energy requirements and lighten their load. France’s FELIN - Fantassin à Équipements et Liaisons Intégrés - program is one of the most advanced in the world. The first phase began in 1996 and started deploying in 2009. Originally the weight target for each soldier was 25 kg – including weapons, ammunition and enough food, water and energy for 24 hours. However, recent revisions have attempted to further reduce weight.
Each FELIN system costs around €26,000. By ensuring that components have maximum interoperability, programs like FELIN can cut weight and ensure that soldiers don’t need multiple batteries. The FELIN system is designed to be powered by two rechargeable Li-ion batteries and French military vehicles are suitably equipped so that infantry can use them to recharge those batteries.
It’s a never-ending process: new technology brings more weight and more power needs, which leads to more trade-offs with regard to what a soldier can carry. Underneath all the kit is a human being who can only carry so much, and that is at the front of our minds when developing batteries to be used by servicemen and women.