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GMC Sierra, Bolt, Sky, Mach E
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819 Posts
Warranties are typically 70% of original capacity at 100K miles. My 2017 Bolt originally had a usable capacity of 57kWh. I now have 99K miles on it and have about 52kWh usable, ~10% reduction. But soon I will have 65kWh when they replace the battery, along with another 100K mile warranty. I almost always charged my Bolt to 100% for the first 3 years, but now I have been charging to 88% (hilltop reserve). I would do about 5 DC fast charges each year, not too often.

For my Mach E I normally only charge to 80%, unless going on a trip.
 

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Registered
GMC Sierra, Bolt, Sky, Mach E
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819 Posts
I have taken my Bolt down to 3% twice, and under 10% a few other times. When it hits 5% it goes into "power reduced" mode. So far in the few months I have had the Mach E, it has not been below 30%.

For battery life, these are probably the best practices:

1) Charge to 80-90% for normal everyday driving, go to 100% for the first leg of any trip
2) Charge every day at home, many short charges are better than fewer deep charges
3) Keep you car plugged in as much as possible during cold and hot temperatures, in order to keep the battery well conditioned

The Bolt manual recommends being plugged in for temperature's below 32F and above 90F, the Mach E recommends below 32F and above 113F. There seems to be an issue with the Mach E though, if plugged in and fully charged, I never hear it run the cooling fan in hot conditions. My Bolt has always run the cooling fan periodically when temps are above 105F and plugged in. Since the last software update in the Bolt, it will even run the cooling when not plugged in.

Based on what GM has learned from the Bolt, I suspect they will recommend not charging all the time to 100% and will also run battery conditioning when not plugged in for all the new Ultium vehicles.
 
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