Quick update on my quest to better understand my remaining battery capacity. My recent charging history (Battery Degradation at 2 years and 50,000 miles | BMW i4 Forum) has shown some steady (but not alarming) degradation in the 2.5 years since I purchased my 2022 i4 M50. My most recent charging data shows my approximate usable battery capacity between 76-77 kWh, which indicates about 5%-6% degradation so far. Again, this isn't too surprising for a car with nearly 60,000 miles and 2.5 years of driving.
I decided to try the 100% to 0% degradation test (inspired by Kyle Conner: 100k mi Tesla Model 3 Performance Battery Degradation & 70-MPH Highway Range Test) to see what my i4 would deliver in terms of total energy on a controlled road test. The test isn't perfect, but it is a good way to estimate the total power drawn from the battery, although there is still a bit of unused energy at the bottom end, something I didn't want to test because I'm not driving my car to the point it doesn't move.
The testing occurred on a dry, sunny day (50 degrees F) without much wind. The test was a loop-style route from my home near Chapel Hill, NC, south on the interstate towards Wilmington, NC, then turned around at 55% SOC and headed back home on the same highway, with a constant speed of 70 mph.
I looped back home with some extra energy, so I burned off the remaining charge on the back roads near my house at 60+/- mph. I reached 0% SOC within a mile of my house and did a couple of back-and-forth trips on the rural highway near my house, driving about 4 miles or so below 0%. I wasn't worried about my range, as the power limiter slowly tapered and I had consistent power all the way back to my driveway (at this point I had only about 33% available power remaining...I wasn't willing to let it slide below that level).
I immediately plugged in and charged from 0% to 100% and noted the total power added (minus the typical losses from Level 2 charging).
Stats and calculations below:
100% - 0% test:
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I decided to try the 100% to 0% degradation test (inspired by Kyle Conner: 100k mi Tesla Model 3 Performance Battery Degradation & 70-MPH Highway Range Test) to see what my i4 would deliver in terms of total energy on a controlled road test. The test isn't perfect, but it is a good way to estimate the total power drawn from the battery, although there is still a bit of unused energy at the bottom end, something I didn't want to test because I'm not driving my car to the point it doesn't move.
The testing occurred on a dry, sunny day (50 degrees F) without much wind. The test was a loop-style route from my home near Chapel Hill, NC, south on the interstate towards Wilmington, NC, then turned around at 55% SOC and headed back home on the same highway, with a constant speed of 70 mph.
I looped back home with some extra energy, so I burned off the remaining charge on the back roads near my house at 60+/- mph. I reached 0% SOC within a mile of my house and did a couple of back-and-forth trips on the rural highway near my house, driving about 4 miles or so below 0%. I wasn't worried about my range, as the power limiter slowly tapered and I had consistent power all the way back to my driveway (at this point I had only about 33% available power remaining...I wasn't willing to let it slide below that level).
I immediately plugged in and charged from 0% to 100% and noted the total power added (minus the typical losses from Level 2 charging).
Stats and calculations below:
100% - 0% test:
- Total miles driven: 238.7 miles
- Average efficiency: 3.15 mi/kWh (note: my average efficiency was bouncing between 3.1 and 3.2 during the final miles of my trip, so figured 3.15 was more representative of the total trip efficiency)
- Estimated battery capacity: 238.7 mi / 3.15 mi/kWh = 75.8 kWh
- Based on a new car usable capacity of 81.5 kWh, my estimated degradation is 7%
- Energy added: 78.7 kWh (adjusted for average Level 2 loss of 5.4%)
- Based on a new car usable capacity of 81.5 kWh, my estimated degradation is 3.5%
