Hmmm, actually it is a charger we used for iPhones. This could be why I struggle to achieve 450mA . I also tried with 2.4A charger this morning and was able to get to 470mA, which is still short of the ~600mA I should be drawing.
Getting a decent power supply and the mosfet you have recommended should go a long way to resolve some of my problems.
Thank you, that is very helpful.
