Why does my kindle fire charge so slow?
My little cousins kindle was 6% then we charged it overnight and it was 42% Yes its the same cable wire from amazon.
Using the cable to charge the Kindle Fire via laptop is quite slow, it will take over over 10 hrs. The Kindle's PowerFast charger will charge it much faster.
Some details on shortening the charging time and optimizing battery life of the Kindle Fire, can be found here:
Hope that helps.