i3 REX home charging problem

[agzand]

I am the relatively new owner of a 2018 i3 REX. I use a 16 amp EVSE (NEM 6-20) on a 20 amp dedicated circuit breaker to charge the car. The 2 chargers that I use (AxFast from Costco and a Morec charger from Amazon) both charge my Honda Clarity PHEV with zero issues. But with my i3 I get random charging errors, particularly if the battery level is low (e.g. 10-20%). I did some digging and looks like the charger throws "overcurrent protection error."

The odd thing is that if I charge the car using a DC fast public charger to bring the battery level up, there is a good chance that my home charger will be working. I tried this a couple of times and it worked.

Now since I get this error with 2 different chargers and the same two chargers work fine with my other car, I suspect the i3 onboard charger could be the culprit. I am wondering if other owners have experienced something similar and whether the onboard charger was responsible for the charging fault? Thank you!

 

[eNate]

I'm not familiar with the fault and since it's doing it with two different EVSEs that work on another vehicle I, too, suspect your i3.

I am curious though -- if in iDrive > Settings > Charging (I think) you set your charge rate to "Reduced" or "Minimum" does it still throw this error?

 

[agzand]

Thanks, I tried changing charge rate on the iDrive, it didn't help. Even the reduced rate (20 amps) is still higher than the rate my EVSE supplies (16 amps). If I could reduce it to 16 or 12 amps maybe it would have helped.

The EVSE seller (Morec) thins the voltage on my circuit could be low, since power is voltage times current, if voltage is low the car can draw higher current, resulting in an overcurrent error. This makes sense except that my other car is capable of 6.6 kW charging (>30 amp) and it has no problem with both EVSEs.

A voltage drop could be due to loose connection inside or outside the panel and could be a hazard, so if the car checks out fine I will have the electrician who installed the EVSE circuit to check voltage.

 

[eNate]

I believe the reduced and minimum rates are proportional to the max available reported by the EVSE. I know that's the case on Level 1. So for example Reduced will take 16A down to 12A, and 12A to 10A or 8A. There's a table in the manual.

I also question the advice Morec gave you. My understanding is that amperage is the constant, so the kWh charging rate your car receives is dependant on voltage, ie plugging in to 240v @16A will charge you faster than 208v @16A, in either case the 16A will remain constant. The EVSE advertises the available amperage to the car, so the car regulates that amperage whatever voltage is being supplied — this assuming the voltage falls within an acceptable tolerance.

 

[agzand]

Thank you, this information is very helpful.

I checked the manual and for Level 1 it is clear that the reduced rate will be proportional to the EVSE supplied rate, for Level 2 it is less clear but it makes sense that the car reduces the rate the same way.

Anyway based on your explanation the problem is most definitely with the onboard charger. I will have the dealer check it next month when my next service is due.