Of batery degradation in the course of say two years, if i charge it between 50% to 80% (most likely will be around 40%ish to 70%ish before starts throtling) every day on a public 45kw/h dc charger on a new 64kw car?
Many people are charging to 100% regularly, including myself at 40k miles, zero degradation. Leaving a battery flat is bad news and possibly leaving it full - for a long time.
Dis, my best guess is 0% degradation in the course of two years. I'm not sure small increments are easily detected so it could easily be 0-2% degradation. That said, are you really putting almost 20 kWh into the battery every day? I guess that's "only" a 100 km return trip daily, but that would suggest you drive more than about 98% of people who work for a living. I suspect the battery would last even longer with little or no degradation if you were charging slower (e.g. overnight) but not everyone can do that, and not everyone wants to drive the same car for 15 years, either! And if you are indeed driving that much (~25,000) km per year, then congratulations and thank you for buying an electric car!
Here's a quick analysis based on the datasheet for the LG Chem E63 cell which was originally specified for an earlier EV with a smaller number of cells, the 40kW Renault Zoe. You might have a different brand cell but I think the characteristics would be similar. Charging watts per cell for the Kona at 47 kW is 47,000 / 298 = 158 W each. Based on the definitions in the Zoe datasheet, 47kW charging is roughly in-between the "22kW" (115 W) and "43kW" (224 W) numbers based on the definitions in the table. For the Zoe model range these represent the highest charging rates. Each graph below shows several tests for cycle life v.s. (a) charging slow, (b) 22 and (c) 43kW charging. They all hit about 1400-1800 full-charge cycles by 80% SoH indicating little difference between charging rates. I need to stress that a "full-charge cycle" means 0% to 97% back to 0% SoC so the 30% you're doing every day means you will get on average (1600 cycles / 0.3 part cycles per day) = 5,333 days or 14.6 years to 80% SoH. Now, there is a further advantage in that you're staying closer to the 50% SoC area which may substantially increase the full-charge cycles possible, based on a graph found at Battery University. I can't quantify that directly for this cell but I really don't think you have anything to worry about. You can also see that fast charging at the 47 kW doesn't noticeably affect life but all this of course disregards time-based degradation which might be a few % per year. We don't have any data for 77 kW charging but I'll venture a guess that this higher rate is best avoided on a frequent basis. Graph (a): Graphs (b) and (c):
Thank you, im driving for Uber so this is the average % spent on a 4 / 6 hour shift, mostly urban, and for now decided to charge it daily on my 20 minute coffee break
