[DeTomaso] Lithium Jump Start Gizmo is this Real???

[Ken Green]

 I Keep seeing these things for sale, are they real?  
http://drivinglife.net/best-lithium-ion-jump-starter/
They seem to claim that a pretty small lithium battery can jump start a car?  Are they just good for a small engine that starts immediately?
If they are real, why can't you put several in parallel for extra cranking, and use them as your car battery?
This one claims up to 20 starts and up to a 6 liter gas engine:
https://www.amazon.com/NOCO-GB40-UltraSafe-Lithium-Starter/dp/B015TKUPIC
Ken
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    I Keep seeing these things for sale, are they real?
   [1]http://drivinglife.net/best-lithium-ion-jump-starter/
   They seem to claim that a pretty small lithium battery can jump start a
   car?  Are they just good for a small engine that starts immediately?
   If they are real, why can't you put several in parallel for extra
   cranking, and use them as your car battery?
   This one claims up to 20 starts and up to a 6 liter gas engine:
   [2]https://www.amazon.com/NOCO-GB40-UltraSafe-Lithium-Starter/dp/B015TK
   UPIC
   Ken

References

   1. http://drivinglife.net/best-lithium-ion-jump-starter/
   2. https://www.amazon.com/NOCO-GB40-UltraSafe-Lithium-Starter/dp/B015TKUPIC