Re: Lost Battery Capacity and Range / Autonomy, Page 2
Posted: Mon Aug 13, 2012 1:30 pm
I did a back-of-the-envelope calculation of how much capacity degradation can be expected in different climates based on simple chemistry. The approach is very simple. I assume that the chemical processes that degrade the battery follow a simple Arrhenius equation with a temperature dependence of the rate of 2-fold per 10C. I then estimate the relative time a battery would sit at a given temperature given the location and then multiply this temperature-time with the temperature specific rate. I did this for four locations: Chicago, Phoenix, Los Angeles, and Seattle. The ambient temperature information is from
http://fs.weatherspark.com.s3.amazonaws ... nt_pct.png" onclick="window.open(this.href);return false;
The temperature resolution is quite poor. The temperature bands are frigid (<15F), freezing (15F-32F), cold (32F-50F), cool (50F-65F), comfortable (65F-75F), warm (75F-85F), hot (85F-100F), and sweltering (>100F). For all bands I took the average temperature in the band and I assumed 10F for frigid and 105F for sweltering. The rate was set to 1 for 20C (room temperature).
These are the total annual rates for the different locations (constant exposure to 20C would equal 1): Chicago (0.69). Phoenix (1.61), Los Angeles (0.81), and Seattle (0.58). The relative rates compared to Chicago are: Phoenix (2.35), Los Angeles (1.18), and Seattle (0.84).
So it would seem that a substantial difference in battery degradation is expected for different locations in the US based on first order chemical assumptions. There is almost a factor of 3 between Phoenix and Seattle.
http://fs.weatherspark.com.s3.amazonaws ... nt_pct.png" onclick="window.open(this.href);return false;
The temperature resolution is quite poor. The temperature bands are frigid (<15F), freezing (15F-32F), cold (32F-50F), cool (50F-65F), comfortable (65F-75F), warm (75F-85F), hot (85F-100F), and sweltering (>100F). For all bands I took the average temperature in the band and I assumed 10F for frigid and 105F for sweltering. The rate was set to 1 for 20C (room temperature).
These are the total annual rates for the different locations (constant exposure to 20C would equal 1): Chicago (0.69). Phoenix (1.61), Los Angeles (0.81), and Seattle (0.58). The relative rates compared to Chicago are: Phoenix (2.35), Los Angeles (1.18), and Seattle (0.84).
So it would seem that a substantial difference in battery degradation is expected for different locations in the US based on first order chemical assumptions. There is almost a factor of 3 between Phoenix and Seattle.