Overcurrent errors

gadgetbazza · 21 August 2024 21:29

Hi.

I recently changed my EV to a car that supports 22kW ac charging on three phase. Being fortunate to have a three phase supply and opting for the 3phase EVSE to get the benefit of 11kW charging up until now, I was looking forward to the faster charging speeds.

However, I have been unable to achieve a stable charge of 22kW as yet. I am getting “over current” errors and have to restart the EVSE hardware to get it to work again. I have slowly reduced the max amps to 25a at which point the charging is stable.

Initially I was hoping that a WiFi firmware upgrade to the latest would resolve this, but unfortunately the problem remains.

I have the voltage being fed in from MQTT rather than using a fixed value.

Is there something else I need to do to support this or is there a problem with my installation I wonder?

EVSE Firmware is 7.1.3.3P and WiFi firmware is v5.1.2

Thanks

glyn.hudson · 21 August 2024 22:39

Could you log the data from the unit to https://emoncms.org so we can see the metrics when the error occurs? Or at least share a screenshot of the EVSE config when the error is present.

What’s probably happening is that your particular car model a bit slower than it should be at reacting to the J1772 pilot signal, resulting in the EVSE throwing an overcurrent error i.e the car is drawing current after the EVSE tells it not to.

github.com

lincomatic/open_evse/blob/master/firmware/open_evse/open_evse.h#L196


      
          //#define HEARTBEAT_SUPERVISION // Heartbeat Supervision support
          
          #ifdef AMMETER
          
          // if OVERCURRENT_THRESHOLD is defined, then EVSE will hard fault in
          // the event that the EV is pulling more current than it's allowed to
          // declare overcurrent when charging amps > pilot amps + OVERCURRENT_THRESHOLD
          #define OVERCURRENT_THRESHOLD 5 // A
          // go to error state overcurrent by OVERCURRENT_THRESHOLD amps
          // for OVERCURRENT_TIMEOUT ms
          #define OVERCURRENT_TIMEOUT 5000UL // ms
          
          // if there's no accurate voltmeter, hardcode voltages
          #ifndef MV_FOR_L1
          #define MV_FOR_L1 120000L       // conventional for North America
          #endif
          #ifndef MV_FOR_L2
          #define MV_FOR_L2 240000L       // conventional for North America
          //  #define MV_FOR_L2 230000L   // conventional for most of the world
          #endif

The overcurrent parameters were tweaked in EVSE controller version 8.2.1. The current stable version is 8.2.2. Your running 7.1.3 which is quite an old version.

There’s no need to flash the 3-phase version since the three-phase calculation is now built into the WiFi config.

Unfortunately, an ISP programmer is required to flash the OpenEVSE controller: https://github.com/OpenEVSE/open_evse?tab=readme-ov-file#flash-pre-compiled-using-avrdude

gadgetbazza · 22 August 2024 06:52

Thanks @glyn.hudson .

I think in a previous conversation it was mentioned that there wasn’t much need to update the main firmware, but then that was probably a couple of years ago!

I already purchased the ISP programmer but after my recent cock up at flashing the ESP I thought I would see how things went for a little bit before moving on to the main board. I’ll read the instructions and get myself prepared to give it a go and let you know.

Thanks
Barry

glyn.hudson · 22 August 2024 10:46

I think this issue only effects a few vehicles which don’t strictly follow the J1772 spec. There’s a good change that the vehicle manufacturer will fix the issue with a manufacturer’s update. What vehicle is it?

gadgetbazza · 22 August 2024 11:22

It’s a Porsche Taycan MY2024 (so 1st Gen, not the revised MY2025)