i3lady wrote:This makes me mad. We have a 2015 i3. We were told that our battery capacity would be around 100 with a slight decrease in milage over the years. Its almost 4 years old now, and 4 mos. ago, my battery started charging only up to 50 mph - who the hell in CA can drive a car with 50 miles capacity?!
If this is the estimated range, it can be quite inaccurate and affected by driving conditions during the previous 18 miles which might not be the same as the current conditions.
i3lady wrote:Not only does the battery not charge to a meaningful capacity, it goes down very fast.
If this is a change from previous behavior not due to colder weather, the capacity of your battery pack might be low.
You could estimate the usable capacity of your battery pack by driving a significant distance and noting the measured efficiency during that drive that iDrive can display in miles/kWh. Note the charge levels at the start and end of this drive. For example, if the charge level at the start was 90% and at the end was 40%, the charge level dropped 50%. If you drove 32 miles at an efficiency of 4 miles/kWh, your drive consumed 32 miles / 4 miles/kWh = 8 kWh of energy. The total usable battery pack capacity would be 8 kWh / 50% = 16 kWh. The nominal usable capacity of your battery pack when new was 18.8 kWh which is apparently the capacity that BMW uses to determine the capacity degradation percentage. The current percentage of the nominal usable capacity would be 16 kWh / 18.8 kWh = 85%.
Note that this is an estimate because the charge level percentages are calculated values that aren't perfectly accurate. BMW dealers have a more accurate procedure to measure the battery pack capacity that involves discharging the battery pack to a low charge level and then measuring the energy needed to fully charge the battery pack.
i3lady wrote:Does anyone know who I can take this issue to besides the dealer? What are the exact numbers for the warranty? (Meaning what is 70% capacity charging capacity in order to trigger the warranty?)
According to the "Lithium-Ion High Voltage Battery Capacity Coverage" section of the i3's Service and Warranty Manual
"If an authorized BMW center’s capacity check concludes that the net battery capacity is less than 70 percent of its original nominal value when it was new, this level of capacity loss is considered excessive."
So you'd need to take your i3 to an authorized BMW center which, in the U.S., is a BMW dealer certified to repair i3's.