2017 FFE Normal battery degradation?

[vkdyer]

My range has dropped over the last couple months. Since my last full charge, I've driven 85.5 miles over 3 days with 8 trips. The battery shows 10% remaining (and only 5 miles). If I add up the kWh for the 8 trips, it comes to 18.5 kWh. The battery has a stated kWh of 33.5. So according to these numbers, I used 90% of the battery but only 18.5 kWh. The car will be 8 years old in April. Is this normal degradation or does it sound like something is wrong?

 

[jghall00]

If you use Forscan, will tell you the remaining kWh in the pack at full charge. Mine was around 25.8 with 68K.

 

[Anti_Climax]

My range has dropped over the last couple months. Since my last full charge, I've driven 85.5 miles over 3 days with 8 trips. The battery shows 10% remaining (and only 5 miles). If I add up the kWh for the 8 trips, it comes to 18.5 kWh. The battery has a stated kWh of 33.5. So according to these numbers, I used 90% of the battery but only 18.5 kWh. The car will be 8 years old in April. Is this normal degradation or does it sound like something is wrong?

33.5kWh is not the available capacity, it's the direct raw capacity of the cells. 100% is 95% SoC and 0% is about 8.5% SoC. So even when absolutely brand new, the available capacity is 29kWh. What you're seeing here suggests your capacity has dropped to about 70% of the nominal value.

If it's been abrupt and recent it could be a single cell triggering the discharge limit before the other cells are near it. In which case the capacity is there but it can't be safely used without drawing a cell down below spec. Going too low on series cells can do REALLY nasty stuff like flip their polarity.

Beyond that, they do have a finite lifespan that targets around 80% after 8 to 10 years. But that is tied to a bunch of factors that vary widely by drivers. At 4-5 years, my original battery had lost around 25% of the available capacity but I have no idea how the original owner treated it. My replacement hasn't degraded nearly as much in the same timeframe.