So, a couple of interesting things happening with charging the Niro. First, as noted in another thread, the car draws maximum amps the entire charging session. In my experience with the other EV's I've owned (a 2013 Leaf and a 2016 Volt), charging rate tends to gradually drop the closer the battery gets to 100% charge. This to to protect the battery over time. It also, probably, prevents excessive heat buildup as the battery reaches close to full capacity. Second, I have noticed that on my L2 charger (charging at 24 amps), that the efficiency is not what I would expect from a L2. As an example, I started charging last night with right around 34% remaining charge. That means that I had right about 42 Kwh that needed to be added to the battery for a full charge. My EVSE reported that it took 48 kwh to completely charge the battery. That is a little shy of 90% efficiency. Typically, L2 charging is somewhere around 95% efficiency, I believe. Third, the car does charge noticeably slower as it reaches 90% or so. In other words, the time to get from 80% to 90% is noticeably faster than the time it takes to get from 90% to 100%- although the EVSE is still reporting drawing the full current (24 amps) during that time. So, I'm wondering if the Niro just handles charging a little differently in that it still draws max current the entire charging session, but as it approaches approx. 90% state of charge, perhaps some of that energy is being diverted to the battery cooling system, so the battery can still charge at a reasonable rate, but not heat up? Just floating a theory here, trying to explain the reason behind the perceived lower than normal efficiency, the readings from the EVSE showing max power draw throughout the charging session, and the fact that it takes noticeably longer to get from 90% to 100% charge.
Have you compared the change in CEC value reported by OBD2 interface to the value reported by your charger? That might give you a more accurate indication of wall-to-battery charging efficiency.
All EVs, and Lithium Ion batteries, are slow to go from 80% to 100%; The higher the state of charge the slower the charging rate. This is why it is common practice, and proper EV etiquette, to stop charging your EV on L3 EVSEs when you reach 80%. The time to get from 80% to 100% on L3 is almost as slow as on an L2 EVSE because the rate of charge slows down significantly. As for your home charging speed, you would be better served with a 30 amp EVSE due to the battery size and the speed increase the onboard charger would allow. With my 30 amp EVSE I get above 7kWh charging speeds. Regarding efficiency, it all depends on your EVSE, the temperature, etc.
Yes, all of that is understood. The weird thing was not that it was slow to charge from 80 to 100 percent. The weird thing was that it was pulling the full amperage while charging slower in that range of charge. The EVSE reported a full 24 amps of current from start to finish on the charge, no tapering. Despite that, the battery still charged slower in that range, even while still pulling the full 24 amps. My EVSE is actually a 40 amp, it's the circuit I have available for the EVSE that is the limiting factor. It's a 30 amp circuit, so max safe sustained amperage is 24.
OK, understood, I seem to have missed the 24 amps the whole way. I have no explanation for that. As for the circuit, I chose to install a 40 amp circuit so I get 30 at the EVSE. Why did you choose to install lower amperage?
Well, it wasn't really a choice to install a lower amerpage. It's just what I had available in my panel at the time. I've been driving electric for about 6.5 years now, but until the Niro I didn't have a vehicle capable of pulling more than 24 amps. I've had the Niro for about 6 weeks, so I'm looking at the possibility of putting in a 50 amp circuit (to have some headroom to charge at 40 amps if needed in future), but also weighing the cost of that vs. the benefit of charging a little faster.
