I use the Anker Astro Pro3 10,000 mAh battery pack strapped to the X5 - with rare exceptions.
It adds weight and bulk but, at the very least, even if you don't want the battery attached full time, carrying it with you allows recharging in the field, so that you're less likely to kill the X5's internal battery by routinely deep cycling it.
It turns out that for any given load (for any given amount of current that you pull from a battery), routinely taking the battery to 100% depth of discharge will cause that battery to die (for lack of a better word) in far less than half as many cycles compared to routinely taking it to only 50% depth of discharge.
And if you routinely take the battery to only 25% depth of discharge, you will find that the battery will survive far more than twice as many cycles as routinely taking it to 50% depth of discharge.
In other words, shallow cycling between fully recharging the battery can yield many more charge cycles than a linear proportion would suggest.
![](https://www.head-fi.org/attachments/1211153/)
![](https://www.head-fi.org/attachments/1211152/)
And there are many 5V external battery packs out there to choose from - larger and smaller than the Anker Astro Pro3.
Still, it's a perfectly valid choice, for the sake of convenience, to deep cycle the X5's internal battery to your heart's content, then when it dies an
earlier death, send it back and pay to have the battery replaced or just toss the X5 in the trash and order a new one. Money = Convenience.