People need to stop looking for black/white answers on this topic. It's not like charging to 100% will cause immediate harm to the battery, but charging to 80% will result in 0 degradation. Lithium batteries, like all batteries, DO age, and their performance drops as they do. How you use them can affect how fast they age. There is plenty of testing data out there if you search for it. Repeatedly using a 100% DoD will age a battery slightly faster than 80%. 80% will age faster than 75%. 75 faster than 70... Whether or not you'll actually notice any performance drop during the time you have the car will vary from one person to the next. It's really quite simple... if you need the full capacity of the battery, then by all means charge it up to 100%. But for times when you don't, how much of an inconvenience is it to adjust your charge based on expected usage? I suppose there are people out there who never know on a daily basis if they're going to be sitting at home or taking a 300m road trip, but I would think MOST people have reasonably predictable usage. If you can't predict your usage, or if you simply don't want to bother, charge it as you please and don't worry about it. You may not notice any difference before you trade it in anyway. If you're someone who likes to optimize things to the nth degree, then charge only as much as you need, with the goal of keeping the average charge level around 50%, and as frequently as possible to reduce the min & max. And only use fast charging when necessary.