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What is a proper response to an EVSE stuck contactor?

1940 Views 1 Reply 2 Participants Last post by  dcb
After 10 years of watching, waiting, planning and hoping, I finally pulled the trigger and purchased an off lease 2014 Fiat 500e.

So far I've just been charging with the 1.4 kw 120V charger that comes with the car. But I'm interested in exploring an EVSE that can maximize the 6.6 kw onboard charger.

Commercial solutions abound of course. But I really just cannot get my head wrapped around the overinflated price for a smart contactor and a handful of safety electronics. I really cannot figure out why a j1772 plug and a few feet of wire clocks in at $150 USD either...

So I'm thinking about putting together a DIY EVSE. OpenEV of course makes the most sense as the design and the software are proven and well tested.

The one thing I cannot figure out is what is the proper response to a stuck contactor condition? Detecting it is simple enough using an optoisolated input between L1/L2 and GND after the contactor. If the contactor is supposed to be open yet the detector sees 60 Hz, then Houston...

But what is a proper response in that case other than failing to deliver a pilot to the vehicle so that it cannot charge due to error? I mean if the contactor is welded closed, then power is being delivered down the cable hot.

What I was thinking was protecting the contactor with a fuse/breaker in the EVSE and if the stuck contact cannot be freed, blowing the safety device by shorting the input power before the contactor to ground using an SSR or a second contactor.

I'm wondering if it's overkill? But it's unsettling to me to have an uncontrolled live wire when the sole purpose of the EVSE is to control that live connection.


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it seems reasonable to alert the user and refuse to charge to me. The other end shouldn't close the relay without the pilot light. The user has to repair or replace the unit to get going again. Maybe some instruction to unplug it when it breaks, or a dedicated led labelled "STUCK CONTACT, UNPLUG UNIT NOW AND REPAIR" or something, but otherwise you are getting into helmet protector protector land.

The plug and cabling and receiver are all pretty well protected, moreso than your average wall outlet, or extension cord, and you should be treating it with at least as much respect. There is no %100 foolproof.
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