DC charging for Leaf over level 1 J1772?

[Wiz Tech]

The standard level 1 charge cable for a Leaf contains a small 12V transformer to power the control electronics and PWM signal. BUT, you could replace that with a 12V regulator running off 120V DC. In which case, you could run the whole thing off DC (ie. Solar panels and batteries without the loss of an inverter). The question is, how would the Leaf onboard charger feel about having DC input? It seems to me it should just be rectifying the AC input before use anyways, and thus shouldn’t care…

 

[nlspace]

It may care about the DC current in the AC filtering magnetics? Also the controller for the boost stage is probably looking for an AC in order to do PFC?

 

[coulomb]

It may care about the DC current in the AC filtering magnetics?

I don't believe so, but I'm no expert on magnetics.

Also the controller for the boost stage is probably looking for an AC in order to do PFC?

That could certainly be a problem. But it often seems to work out OK. After all, Elcon chargers (often used in EV conversions) seem to work fine with DC input, at least at low power levels. Maybe the PFC chips have a special check for DC input.

My MG ZS EV (Chinese designed and built) specifies AC or DC as the input to the Combined Charging Unit (the on-board charger), though it's possible that this is a poor translation from Chinese to English.

The problem is, an EV's on-board charger is a bit expensive to experiment with, if there is any chance that something could go wrong.

 

[cornbinder89]

I must admit to wondering the same thing, but nowhere near brave enough to risk the charger to try it.

 

[nlspace]

My MG ZS EV (Chinese designed and built) specifies AC or DC as the input to the Combined Charging Unit (the on-board charger),

That is interesting for sure--have you taken a look inside yet, or is it still too new to mess with?

Concerning the DC current in the Inductors, i was thinking maybe the DC resistance would be much lower than the AC impedance at 100-120 Hz?

Solar can be used in numerous ways, but unless you had an extra OBC to play with, then this could be an expensive experiment.

 

[MikeinPA]

DC Level 1 appears to be built into the J1772 standard, see page 34 of this https://downloads.regulations.gov/FHWA-2022-0008-0402/attachment_1.pdf Interesting

 

[cornbinder89]

I found that interesting. I didn't read it cover to cover, but it seams like the J1772 supports DC charging but it is not clear that the car's onboard must also. So I'd go forward with caution. It looks like it would need a dedicated DC EVSE, but I could be reading that wrong.

 

[MikeinPA]

Yes, it shows a separate set of relays needed for the L1 DC. Almost certainly not present in the Leaf PDM.

But the idea of feeding 400 VDC through L1, from a PV system that is using an HV battery, is interesting.

 

[coulomb]

That is interesting for sure--have you taken a look inside yet, or is it still too new to mess with?

Still too new.

 

[WetEV]

The standard level 1 charge cable for a Leaf contains a small 12V transformer to power the control electronics and PWM signal. BUT, you could replace that with a 12V regulator running off 120V DC. In which case, you could run the whole thing off DC (ie. Solar panels and batteries without the loss of an inverter). The question is, how would the Leaf onboard charger feel about having DC input? It seems to me it should just be rectifying the AC input before use anyways, and thus shouldn’t care…

The rectifier produces closer to the peak voltage, not the RMS voltage. So would want closer to 150 VDC.

Relay on input might be a problem, switching DC with a relay is more of a problem than AC. Some relays are rated for both, most relays are not.