I am attempting to test a Non-Isolated 12V Orion DC-DC Charger before setting it up in the back of my car for a campervan setup. I am wondering if I can connect the input of the Orion to a DC charger that connects to a 120V wall plug directly, instead of connecting it to my alternator or an external battery. I've used the wall plug DC charger to charge the battery LiFePo4 I am planning to install. Thanks!