After a little research I see that the Nexus 5 is safe to and capable of 1.5mA but the stock charger is rated at only 1.2mA.
I've tried a number of 3rd party 2000mA AC adapters but these all show as USB charging, so capped at 500mA.
Anyone got anything tried and tested that will give me this. Also looking for similar for my car. I have one that will charge at 1mA but would like more if possible.