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I am new to the forum, I posted a message yesterday, but it did not display in forum, sorry it is duplicated.

The wikipedia shows that EVSE DC output voltage is 50VDC - 1000VDC, if we design and build a DC charger output voltage over 50VDC, will it work to charge EV DC directly?

I read comments most said that EV DC charging voltage should be 400VDC, that is not just contradict to the wikpedia but also from Chris Howell presentation Electric Vehicle Charging.

Thank you very much.

Kind regards,

Jupiter

It is possible.

SAE J1772 Oct 2017 Says that DC Level 1 off-board charging at 50-1000VDC up to 80A happens through the AC input.  The communication mechanism is defined in several other SAE standards mentioned within.  I haven't read the Jan 2024 revision yet, but here is the revision in the federal register https://downloads.regulations.gov/FHWA-2022-0008-0402/attachment_1.pdf

I'm working on a 50-200v DC Level 1 EVSE and compatible vehicle charge controller, but just getting started.

Dustin Maki

Dustin - DC Level 1 and 2 are both optional. Level 2 is now known as CCS and I'm not familiar with any modern car (other than Teslas) that supports DC charging over AC pins.

800V platforms excluded (those usually have internal booster, or an ability to reconfigure battery into 400V) all that Level 1 or 2 DC charging does is expose the HV battery to the connector. There is no electronics in between the external charger and the battery in this configuration. The external charger has to do all the work. Including matching the voltage of the battery. 

Standard states 50 to 1000V not because all cars will charge at 50V but because some older low power EV had a 48V systems so chargers ideally should be able to go that low. The charger has to match the battery charging voltage or it will not be able to charge anything. Also chargers do not have to support the entire range or voltages in the standard - many chargers go up to 500V that is why 800V platform EVs have on board voltage boosters or ability to switch their battery into 2x400V configuration.

Most modern EVs are 400V platforms so 200V DC charger will not be able to charge those. And, if not protected adequately, even completely discharged modern EV with 300V on the battery pack will blow it up. 

Also building your own lithium battery charger can be extremely dangerous - if it misbehaves It can damage the car, the battery or cause a fire. While I like DIY projects I don't think that this one is worth the risk.