Tesla Motors Club

I realize this topic has been discussed before but I wanted to find out if there's anything new in the area of a portable 12V jump starter to keep handy just in case the Tesla 12V battery dies. For a Tesla with a dead 12V battery, how many Amps/Peak Amps should the jump starter battery output?

Has anyone found one with the following features?

• Battery has a long shelf life so I can keep it in the car for months at a time and not worry about if it has a sufficient level of charge.
• What type of battery chemistry should I look for?
  
• Would like the battery to be powerful enough to jump start an ICE SUV or car just so I have the option of helping out someone in an ICE who is stranded with a dead battery.
  
• Would be great if it had a USB output for emergency power.
• Smaller and lighter the better (while still being able to jump start a Tesla or ICE SUV)

A nice to have feature that is not required is an air compressor so you can inflate tires if needed.

What's the best place in the car to keep this battery so I can get to it even if the 12V battery is completely dead? Would the frunk be the best place to store it as there is a manual pull cable to open the frunk?