RTFM and go from there
"any standard USB port compatible with USB batery charging 1.2 (BC1.2)can be used to charge your battery" (eq800 manual)
and
"a high capacity (>1.7A @5V) charge is used" (eq800 manual)
so
your charger of "5v 0.5A" is low but sufficient. remember from the docs "however charge times may be longer if using low power options" (eq800 manual).
personally
i've never like hard charging a battery with high capacity anything. I bring along portable batteries to extend life and give full on charges only when I'm not gonna be using the battery for a day or two, giving a rest after charge and a slow moderate easy ingested charge (to me) makes batteries live for decades.
But
I also come from the generation that coined the term "battery memory". . follow normal battery usage behaviors (never less than 1/8 charge and always go to full charge without interuption) and store for long periods at 1/3 to 1/2 charge. never let it deplete to no charge. luckily the eqX00 has a reasonably serviceable battery
the trick is
knowing the battery and treating as it needs and understanding it's full life cycle as intended by engineering design.
-TK