You can look up the "amp-hour" rating for the battery in that jump starter pack.
Multiply by 12 (volts) and you get the estimated watt-hr capacity.
Divide by 2. Save this number
Take each you plan to charge and multiply nominal voltage by mah capacity. Divide by 1000.
That will be watt-hr capacity of the pack.
Divide the number saved above (1/2 watt-hr of the source) by the watt-hr of the battery to be charged. You now have the number of recharges you can expect. (without damaging the source battery)