Has anyone used Startmonkey or Lithium equivalent ?

I note that the shop is carrying ads for the more powerful 400A version of Startmonkey lithium jump starter and I find the specs confusing and wonder if anyone has more detail.

I get a little worried when I see statements like "delivers a jump-start current of 12Volts at 400Amps" and " Maximum jump-start current: 400A, 4,800watts in 6-8 seconds "

In reality its a secondary battery of 21AH that is used to dump some charge into a good but flat battery which together then start the car, in this mode everything is fine and I'm sure it delivers.

Implied in these specs is that it can deliver 400A and start a car which isn't really true.

It may deliver 400A for an instant but its own spec 4800 watts in 6-8 seconds" is an average of approx 66 amps.
(I also don't think the leads on Smartmonkey wouldn't handle 400A for long).

I.E. Its unlikely to start a car which has a destroyed (and hence disconnected) battery.

Ever since the manual option was deleted from the GU 4800 patrols I love and I had to go automatic, I have carried my own version which is a 21AH GEL Cel permanently connected to car via a low volts drop diode.
It has Anderson plugs connected for quick jump starts and running inverters etc.


This Smartmonkey appears to be much the same functionality as my Gel Cell system, however if its weight claim of 1.1kg for 21AH is true then its represents an incredible capacity/kg specification as gel cells are around 5kg and for this reason alone would be worth my consideration .