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Hi, I have a brand new, less than 48 hours old v5.5 board which worked for a few good charges, but now won't hold the relay closed for more than about 30 seconds.  It starts humming, then releases and gives a grounding error.  The ground error makes since, as the test is expecting a closed relay.  Disconnected, the relay draws 158mA, which seems to be in spec.  I suspect this is an issue with the Q2 transistor not sinking enough current, and the coil voltage falls off.  Any thoughts?

Thanks,

Chad

I've got the exact same problem.  I received my unit a few days ago and just got it built and tried today.  I have a older unit (2 yrs old) and it's working like a champ.  With this one, under low amps it works fine (<10A).  Greater than 11A you can start hearing it hum.  If I disable the Ground Monitoring it will go up to ~21A before it'll reset.  

Problem solved.  There is PWM output on the relay module.  Humming and disconnect means it is set too low.  

Advice from Open EVSE:

OpenEVSE hardware version 5.5 and above supports variable relay power. The relay is closed at full power then after a set time the power is decreases. Differences in hardware and temperature can require slightly more hold power.

To alter the settings login to OpenEVSE WiFi

Click the System tab

Enable Developer Mode

Click the RAPI tab

Enter the command $Z0 xxx yyy

xxx = the number of ms to run 100% power

yyy = the power out of 255 (example 90/255 = 0.35 or 35% power)

Recommended setting is $Z0 100 105