Charging update

 We have struggled with public charging, and have not had success at a public charger yet, but we have been able to charge at other peoples homes setup with chargers.

We have learned that in the image taken from Wiki J1772 interface:

 

In our cable from the Vehicle Inlet to the charger (Vehicle Controller) the R5 2.7k resistor had been included and hidden in the cable wrap.  Thus as we were adding R3 and R2 we were inadvertently connecting their ground to the top of R5 and not ground such that the resistance signal back to the EVSE Controller was not 882 ohms but instead 3582 ohm and so the controller would indicate ready, but not charge.

The wiring error has been corrected, but the opportunity to plug into a public station has not happened yet.

Our issue with the charger shutting down early with a high voltage error has been answered by the Brusa support team.

From BRUSA support.

Hi,

 

I think you have done everything right basically, ... What you probably didn’t know (and which is not described clearly I admit) is that the "SDT Batt VoltHi: ERR" is produced by a crowbar like circuitry, which measures output voltage very fast but not very accurately. This is intended to avoid damage to attached circuitry in case the battery suddenly disconnects and causes a load drop to the charger. The resulting voltage overswing might damage sensitive electronics like DCDC-converters, amp-hour counters etc., so it must be avoided by fast shutdown of the power stage.

 

Now: As I said, this fast measurement circuit is neither precise nor is it well filtered, so any peak / disturbance / noise etc will trigger the shutdown and throw the error.

The value which controls this crowbar/shutdown circuitry is the second value in the orange/yellow fields, which says  «switch off immediately if Battery voltage above [V]» 

 

And this value is set to 390V in your case, which is very close to the 384V you intend to reach. So remedy is pretty easy: Add a healthy headroom to the «switch off immediately if Battery voltage above [V]» value, let’s say you set the limit to 460V, and you’re done. Required headroom depends on various influencing parameters, however with a margin of 20% you’ll probably never see any nuisance tripping of this crowbar again.

We changed the value to 403V, =4.2*96 the highest the cells want to see.  The system works now.