1500mAh is only a 1.5A charge. That's standard for most battery packs, nothing great. My old Motorola P4000 charges at 1.5A.

This Anker 20,100mAh on Amazon is $79.99 (not Prime) and supports up to 2.4A on standard USB and 3A on Type-C.

Here's a similar Anker 20,100mAh one without Type-C for only $45.99 (Prime). It is limited to 2.4A like all standard USB ports though. It does come with the wall adapter too however.

There's also this 20,100mAh one from RavPower for $55.99 (Prime) that's the same capacity and 2.4A USB and 3A Type-C capability (except it also supports QuickCharge2.0)

Or this RavPower 26,800mAh behemoth for only $49.99 (Prime) without Type-C that will charge up to 2.4A via stadard USB.

Both of the RavPower devices have good reviews and I've never had an issue with them or Anker before.

Just curious which one you got? I got this 20,000 mAh one and I don't think I've gotten it under 3/4 charge yet after 2 charges (I have a Droid Turbo 2)