External Batteries - Laptop Recommendation

Hi:

I'm the slightly disappointed owner of an HP Spectre. Wonderful little laptop but I just found out today I cannot run the computer off an external battery. I'm a ham radio operator and I'd like to see if I can take a laptop out on some of my outings (SOTA, POTA, camping).

Can someone recommend a good, light weight laptop somewhat close in specs to an HP Spectre (T9Y18AV) that can accept an external battery pack? While you're at it, maybe you can suggest the battery pack to use. I'm hoping for someone with experience who might be able to tell me how much time I could expect out of an external pack.

Thanks,

Kevin