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 ⇐   January 7th, 2024   ⇏ 

Copyright 2024 Michael Anttila

Ever since my friends and I bought our Bolt EVs, some of us have been keeping track of our battery health stats. Every few months or so, we take a reading and enter it into a spreadsheet. Since the Bolt went through a battery recall, we have stats on quite a few batteries now. Steve recently switched from a Bolt to a Ford Lightning, so now we have started collecting stats on the battery in his truck as well.

The goal is to see how much the batteries degrade over time, and compare that degradation to predicted degradation curves from the car companies. So far, the degradation curves are tracking the predictions almost perfectly.

Of course, we are all competitive, so I put together this chart which compares all of our batteries with each other, with trend lines showing who is experiencing less degradation over time. So far, thanks in part to what I think was an anomalous reading I took after my battery got swapped, the new battery in my Bolt appears to be getting better over time! I expect this trend will change as I take more readings.

There are two charts, and the main reason for this is because I drive my Bolt a LOT, commuting to Kitchener every day for work, while Kris drives his Bolt very little. So, the first chart tracks battery health over mileage, and the second chart tracks battery health over time. Even though the car companies predict battery health based on mileage, it looks to me like time might be the most important factor here. It seems the battery will degrade at a similar rate even if you barely ever use the car. I'm not sure... maybe this is for YOU to decide after looking at these charts!

Technical Details: These are graphs I made in Google Sheets. An anonymized version of the data is available here for people to play with. It is a little behind because I only copy the data over from the master sheet periodically. It also contains a few entries from random people on the internet.

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