Thanks. I think I'll go for an external battery because the original is good enough for daily use.

BTW, I notice that the Anker Astro3E delivers 3A while the New Trent IMP120D delivers 1A.

Does it mean that an electric device doesn't care it it's fed more amps that it needs, or is there an upper limit to the Ah the battery should deliver so that it doesn't harm the device?