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So, in the "real world", and in long term conditioning tests etc, how much of a genuine difference does this make to battery life and charge capacity?

It seems almost counter intuitive to someone who grew up with old NiCad batteries for some time, where by running them down and charging them fully was best to avoid "memory" effects.

I assume (as I've been rather slack on this) it's due to stress and in particular heat related issues? But really, is there much data, as somehow that 100% charge (which I stopped using after just over a month) feels somehow better and more reassuring than the 80%, yet I don't want to be regretting it in three years time?
 

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I don't know whether you have seen this from plug in America. It's a very interesting read.

I believe you can still input to their survey - looking at the stats, only one Leaf from the UK has been submitted.
 

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That's really interesting, just a skim read and it doesn't really show much conclusively, which is actually a good thing (if not entirely helpful if people are looking for black/white answers).

This section stood out under the high mileage section:

The top three high-mileage vehicles in the survey report having driven 35,000, 46,000, and 57,600 without
losing a capacity bar. The following table presents survey data for those vehicles. All three vehicles are
being charged to 100% on a daily basis, with the top two being full charged multiple times per day. The
three vehicles have received a significant number of quick charges. The two that reported battery test
results received full 20-point assessments.

By the Gid measurement, vehicle #240 is at 87.2% of nominal full capacity after 57,600 miles. The owner
has a typical trip distance of 130 miles, does two 100% chargers per day, and is now driving down to the
low battery warning twice per day. Despite this heavy use regimen, this nearly-60,000-mile car has more
battery capacity than some hot-weather cars with as little as 7,000 miles. Linear extrapolation suggests this
vehicle will lose its first capacity bar at approximately 80,000 miles, although the author expects that
capacity loss will be faster than a linear model would suggest if the current use level is continued due to the
increased depth of battery discharge required.

It would be very helpful to get Gid readings from more high-mileage vehicles to establish an expected
battery loss rate for LEAFs and compare how that rate varies with climate.
Overall, it appears how you use the battery has little impact on the long(er) term condition. This to me is a good thing as, quite honestly, I don't really like the 80% charge capacity as I tend to top up if range drops below 30 miles, as I never want to be in an emergency situation where I need the Leaf and can't get a reasonable distance, which in Milton Keynes is around 30 miles in my view (most major "local" places can be reached with that plus a top-up).
 
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