how i wired it today

i have a 15000mah lithium battery, charges at 12.6v, it used to charge fine wiring it to the battery out of the solar charge controller, but when one of the plugs broke, (which i replaced) the solar charge controller didnt show a stable voltage and the wire got warm. so today from the output of the solar charge to the voltage step up, then out of the voltage step up at 12.6v, and it has been charging for about an hour with a cooler cable showing the watts in to the battery between 5watts and 9watts.