The vehicle charger stands between the charging station and the vehicle battery. It converts the voltage from AC to DC, steps up the voltage from 120V/240V to the pack voltage of 300-400V, regulates the charging current, and monitors the pack voltage. Contrary to what some might think, the thing mounted on the garage wall is not the charger, but rather a module within the vehicle that does a lot of power conversion.
A few years ago there were only two choices for an on-board charger: low power, cheap Chinese chargers that would die relatively quickly, or extremely expensive, configurable, huge Brusa chargers.
With the introduction of a greater number of OEM BEVs, the DIY landscape is slowly changing. I would strongly recommend to choose an OEM charger as they are cheaper, more reliable, and usually higher performance.
Although I would never recommend a DC drive-train to anyone, I want point out that most of these chargers are designed for the higher voltages of AC drive-trains. If you have a pack voltage not in the 300-400V range I would pay special attention to the tighter voltage windows of these OEM chargers.
I chose the Eltek Valeo 67.130.0 charger. It was designed to OEM spec for use in the Volvo V60 and is capable of supplying 3kW of power from 250-420V. The unit is also liquid cooled and rated IP67, making it virtually weather proof for mounting anywhere inside/outside/underneath of the vehicle.
Another attractive feature of this particular charger is its integration to the Orion BMS. While charging, the BMS and the charger need to interact continuously to ensure that the battery is charged correctly and safely. Towards the upper end of the battery State of Charger (SOW), the charger must reduce power to ensure that the battery cell voltages don't go above thresholds.