On-Board Charging (AC):
Pretty much all EVs around have on-board battery chargers. This is important because that way, you can plug in anywhere there is mains electricity. It might however take 18 or 20 hours to fully charge up on a standard outlet, so higher power solutions are also common. An on-board charger is the best way to routinely charge an EVs battery, as the charger can be controlled closely by the car's battery management system, and it puts the least stress on the battery (charging generates heat in the battery - charging at excessively high rates can damage cells).
Onboard chargers typically follow the SAE-J1772 electrical standard and use the IEC 62196 standard "Type 2 (Mennekes)" connector. Many BMS units have the capability to provide control signals for J1772, and using the Type 2 inlet on the car is the best for compatibility with public charging infrastructure (in the EU, it is regulated that all public AC chargers use the Type 2 connector and follow J1772 signalling standards). It is possible to use other connectors for on-board chargers, but that will necessitate carrying a set of plug & socket adaptors if one wishes to use public EV chargers.
Charging rates for On-board AC charging depend on the power rating of the charger that you pick. If you want to charge at a rate higher than 3kW (13A in the 230VAC world), you will need a specific outlet installed in your charging location (or use a public charger). If you are unfortunate to live in a part of the world that has 110/120V mains voltage, you will probably want a 230/240V circuit installed where you normally charge. The best on-board chargers will have communication features built in - which paired with an appropriate BMS, will allow the BMS to limit charge current and protect against over-voltage etc.
DC Charging:
DC Charging enables faster charge rates by moving the charger (AC-to-DC) out of the car, allowing for large high-power kerbside units to supply the HVDC power that the battery needs directly. The car is required to communicate with DC chargers as the car must tell the charger exactly what voltage and current it needs to prevent damage.
There are two major (non-Tesla) standards for DC charging at present; CHAdeMO and CCS.
- CHAdeMO, as seen on the Nissan Leaf is a fairly simple standard to interface with. Many BMS units have built-in support for Chademo, and therefore implementation is as "simple" as finding an inlet socket and installing it as guided in the BMS manual.
- CCS, although it is more common globally is much harder to interface with from a DIY perspective (as of the time of writing 05/2020, there are no off-the-shelf CCS compatible DIY solutions avaliable.)
High-voltage DC safety must be carefully considered when working out how to integrate DC fast/rapid charging standards, as well as considerations for battery cooling and current capacity of cables etc.
