Hi Andy
Sorry about the delay.
I bought an off the shelf one from jaycar and also bought a kit and made my own as well.
The one I made can handle 20 amps at 19 volts so its got heaps of headroom.
This one
https://www.jaycar.com.au/150w-car-l...upply/p/MP3472
works fine and has reasonably clean electronics.
Hope this helps
Andy
PS
Is everyone called andy here?