This EV ownership is an interesting learning curve ! Had our GT line Zoe for about three months now. Love the car but we've had intermittent charging issues at home on OIG. We've recently had a few days away at a cottage and the car would not charge on their 7kw charger . Both properties have TT earthing systems - earth rod in our case.
On reading around it seems the ZOE does earth resistance checks to ensure the charge session is 'safe' and if the resistance is too high it will not start a charge. I am presuming this is the case in the two properties. Further reading and applying some common sense thinking the earth resistence goes up when its cold and more so when prolonged dry conditions affect the substrate the earth rod is installed into. So today we had a failed OIG overnight charge, been very dry here and very cold = perfect conditions to increase the resistance to earth via the earth rod at our property. I tried a bump charge and got the EV is preventing the charge from the Zappi... a good clue. So I poured a couple of buckets of water into the ground around the earth rod and left it half an hour. Re started the bump charge and it ran perfectly !!
So it seems my property is in need of a check for either a new earth rode or a better type of tt earthing system (plate not rod etc) BTW it was rewired 7 years ago. Ive asked Renault for the spec re required resistance setting the Zoe is seeking to safely. ( for the Zoe) to start the charge. We have also got the Zoe booked in for a full check and software update at the main dealers as I am sure I have read that there is a change to the sensitivity setting to reduce instances of this issue - my friends Kia has never had an issue charging....
Be interested to hear from anyone else who may have experienced such issues. Plus if any of my thinking is flawed please jump in or if you happen to know what the Zoe's parameters are for the resistance it needs to find to progress to a charge even better ?
53 ohms is reasonably good. But if that was done in wet weather, it could have deteriorated over time. A good electrician will know all sorts of ways to get the resistance down, other than tipping water on it.
It sounds to me like you are on the right line. But I have no idea what earth resistance the Zoe considers acceptable.
A single earth rod can be unpredictable. The guidance in the UK is that it should be less than 200 ohms. Anything over 1667 ohms is getting dangerous (it may not even pass enough current through you to trip an RCD). But the resistance will vary with soil conditions, and something that is OK in wet weather may be poor in dry weather.