From: lwcamp@gmail.com   
      
   On Sunday, February 26, 2017 at 4:14:47 PM UTC-8, nu...@bid.nes wrote:   
      
   >   High-energy-density batteries are DANGEROUS. Example, exploding phones and   
   burning cars. Armoring them makes the weapon heavier.   
      
   Note that the problem with modern batteries isn't the energy they store.  It's   
   that the electrolyte is flammable.  Solid state electrolytes currently being   
   researched, for example, would make batteries much safer while also allowing   
   higher specific    
   energies and energy densities (and for some of the solid electrolytes, faster   
   charging and discharging).   
      
   Since energy and weight/size of power packs has been brought up, note that   
   high-end modern commercially available Li-ion batteries can store about 1   
   MJ/kg.  A complete cartridge for a .30-06 rifle (bullet, powder, primer, and   
   case) has a mass of 27 grams    
   (I just happen to have one right here, and a reloading balance), of which 10   
   grams is the bullet and 13 grams is the brass case.  This loading would have a   
   muzzle energy of just under 4 kJ (which probably represents about 15 kJ worth   
   of energy in the    
   powder).  A beam weapon of comparable energy using a modern Li-ion battery   
   would require 4 grams divided by its efficiency at turning electricity into   
   beam energy, per shot.  If the efficiency is more than 15%, the ammunition of   
   the beam weapon would    
   weigh less than that of the slug-thrower.  Note that modern high energy fiber   
   lasers (like the ones currently being developed for weapons) run at about 30%   
   efficient.  And that's with modern technology.  When you get some of the   
   battery tech that's    
   currently in the pipeline but still has some kinks to work out into full   
   production, it looks even better for the directed energy weapon.   
      
   (I'm glossing over specific power issues here, as opposed to specific energy.    
   Using Li-ion would require a long recharge time between shots.  Metalic   
   lithium or sodium batteries with solid electrolytes look to have better   
   specific power than Li-ion, as    
   well as improved specific energy and safety, but by how much I'm not sure.    
   Also, if you want a comparable amount of damage from the same amount of   
   energy, you really need the beam to be pulsed rather than the CW beams of   
   today's laser weapons.  Oh, and    
   you will need to make the laser itself much lighter.)   
      
   >   And a cable tethering the weapon to the soldier? No frickin' way. That's   
   just asking to snare it on something and get the user killed.   
      
   With less weight per shot, there's no reason not to mount the battery directly   
   on the weapon.  Or, if you want really speculative science fiction stuff, try   
   inductive charging of your beam weapon.   
      
   Luke   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)