> On Mar 25, 2015, at 9:11 AM, Michael Ross via EV <[email protected]> wrote: > > According to my understanding of Li ion cells, it is possible to select > cells, make packs and manage them for nearly unlimited life with no loss of > capacity. You have to cool them, oversize them, undercharge them, and under > discharge them. Not many EV manufacturers on that path yet. Here is > hoping the new testing catches on and they all wise up. >
The undercharging and under discharging seems to be what Nissan does (at least with my 2011 leaf). I consider fully discharged when I have driven a few miles of commercial/residential (25mph - 35mph) streets past where it shuts off the instrumentation in an attempt to make the driver think the pack is dead. Charging from this point to what the instrumentation indicates is 100% charged (12 bars) takes a little less than 5 hours with the 3.3KW charger. That says they use about 16KWH (~5 hours * 3.3KW - something for charger inefficiency) of the pack’s total capacity. The total capacity gauge now has 11 of 12 bars remaining, meaning the original 24KWH pack is now about 22KWH. 6KWH of the current 22KWH (about 25%) is not being used. Since I charge to 80% normally, I only charge to 13KWH (about 60%). I usually use about 80% of this according to their instrumentation. I’ve had the car for 44 months and have 40,000 miles on it. Their instrumentation is not very linear. When fully (100%) charged, the state of charge gauge indicates 12 bars. The 12th bar lasts for about 3 miles on residential/commercial (25mph - 45mph) streets. The 11th bar lasts for another 4.5 or maybe 5 miles. The 10th bar last at most 2.5 miles. A week ago, I charged to 100% (12 bars) and drove to a destination 36 miles away. I made sure to limit the speed to 50MPH or less even when the legal limits were higher. I also did not use the climate control. I reached my destination about a mile past losing the 5th bar (total of 8 bars consumed — 4 left). I drove back home using the same driving style on the same level route with a slight detour for lunch. When I got home 37.5 miles later, I still had some of the last bar left. The first 36 miles took 8 bars, the last 37.5 miles took less than 4 bars. The state of charge algorithm also removes one of the bars every time the car is power cycled if more than half a bar is used. That is very annoying. I get out of the car with four bars remaining, and get back in with just three. It eventually recovers from this mistake, but it means I have to remember where it was when I turned the car off. The only thing I will say about the miles remaining meter is that it is inaccurate. The display is disabled when the number would go below four, so it wouldn’t even say zero when the pack was completely dead. Ed _______________________________________________ UNSUBSCRIBE: http://www.evdl.org/help/index.html#usub http://lists.evdl.org/listinfo.cgi/ev-evdl.org For EV drag racing discussion, please use NEDRA (http://groups.yahoo.com/group/NEDRA)
