The nomad 7 is a 7 watt panel. IE at 14V (typical output) the solar panel at MAX efficiency, perfect sun load perpendicular to panel surface the entire time, will out 0.5A. Again this is max. The 17ah battery in the B&D 400 jump pack would take 34 hours of perfect conditions to charge. But please note that the B&D 400 manual states "do not charge with 12Vdc systems for greater that 5 hour periods as it could damage or shorten the life of the battery" I assume, but you know what that means, that the 12Vdc charge circuit is not monitored and just allows it to be charged constantly so with the little charge you are giving it, again assuming 100% perfect conditions, it could probably sit on the charge approx that time without real damage, but don't quote me on that. Lets assume you have 14 hours of good light and you tweak and adjust the panel just right all day, it would take greater than 2 days to charge the jump pack. Please ntoe this is assuming 0 battery drain, perfect 100% efficiency, no clouds, etc, so its pretty unrealistic, but still its stated.
I would look elsewhere for a charging system. When I get my new place I will have solar back up built in to certain outlets with a large bank of Trojan T-105s or the like to provide the power when needed. Currently my back up in my rental is all portable panels that I have taken hiking and camping on week long outings. I have 6 10watt and 2 28 watt powerfilm panels. These can be ganged together for increased out put. that gives me 2 60 watt panels (or close to it) if needed. Even at half efficiency, it would still take me a good deal of time to charge a battery (which I would not do), but I can (and have used them) use the 12V charger on my cell phones, scanner, radio, and AA battery charger to make sure I'm never in the dark/ without comms/ or some sort of entertainment even if its just listening to people around the valley on their hams, worse comes to worse Ill power up the Honda EU2000 for a while with the 15 gallons of stored gas I always keep around and keep the fridge going in cycles and charge stuff then too.