Don’t forget to add flux to the joint! Especially for large ones like a charger, the “flux core” isn’t going to be enough. That core is just to keep the flux present as the solder flows, it won’t help remove the oxide layers from the surfaces before starting.
And use a temperature-controlled iron if possible. Much more likely to work properly, less likely to destroy the board by lifting a pad. 350°C should be plenty for most solder alloys.