A portable battery booster for providing a compact, light, and energy efficient battery to jump start a vehicle. The portable battery booster generally includes a housing, a battery means adapted to be received by the housing, a pair of cable means, each of the cable means having a proximal end and a distal end, the proximal end electrically connected to the battery means and the distal end detachably connected to a discharged battery of the vehicle. The battery is generally comprised of one or more batteries having the type of primary lithium-metal, rechargeable lithium-ion, and/or lithium-polymer and more specifically preferably comprised of lithium iron phosphate for fast charging, small size, and high performance. The battery may also be connected to one or more supercapacitors, an internal CPU, DC/DC converter, etc. to increase performance. The cable means includes jaws that detachably connect to the housing in a flush and sleek manner.