It's very likely that we'll end up with tiered batteries in EV's before long. Some amount of the capacity will be fast charge/discharge, some amount of it will be capacity with slower charge/discharge with a higher density available.

Think of it like modern SLC backed QLC flash storage. As long as the usage profile fits inside of the cache, it runs as though the entire system is cache.

Is charge time important because you can't install a L2 charger at home / apartment to keep it "always charged" or because your usage pattern is too heavy duty for a 30 minute break every 200-300mi?

If it's just the former, the slow steady march of EV mindshare might solve your needs before the "L4" super-fast-charging battery. I am starting to see L2 chargers pop up in apartment parking lots, for example. IMO, "always charged" is significantly more convenient than short stops at a station, so it would still be desirable in a world where "L4" batteries and stations were common.

The latter, actually. I'd much prefer to stop for five minutes every 2 hours than 30 minutes every 4 hours.

I'd prefer shorter times on road trip charging, too. But I still ended up buying an EV because I only need road trip fast charging a few times a year, and now I don't have to carve out 20 minutes every couple weeks to go find a gas station and fill up. The overall time savings for me is significant.

The current state of the art is somewhere in between with 18 minutes per ~3 hours. It even helps to split charging into shorter sessions (2x 9 minutes), because batteries charge fastest when they're about 25% full.

Keep in mind that EVs charge unattended, so you only spend a minute plugging in, and can leave to get a coffee, etc.

How 'guaranteed' is that rate? I don't keep up with it like I probably should, but seem to often read that some chargers are outdated, and sometimes you have to 'share' if somebody else is charging nearby?

In the EU, there are Ionity and Fastned networks that can guarantee their chargers will be fast enough for this (>=250kW), and together they have a pretty decent coverage along major highways.

There are setups that have their max rated power per dispenser (“pump”), and halve it if two cars are plugged in to the same dispenser at the same time. Good chargers can do 300kW. If that splits to 150kW it’s not too bad - maybe 5 min slower, rather than double. That’s because the max speed the car can take is a curve, and that only flattens the peak.

However, for the 18-min charging the biggest gotcha is the temperature. In Hyundai/Kia it requires the battery to be at 20-25°C. That’s easy in the summer. In the winter the charging speed can drop as low as 80kW.

Last time we had to fast charge on the way to Yosemite, we had lunch at a strategically parked taco truck in the same lot (they even had a picnic table).

We would have walked to a nearby restaurant if needed.

I also think the roadtrip inconvenience is vastly overblown. Had an EV since 2018. It is our roadtrip car. It turns 12 hour roadtrips to 14 hour trips but if you plan around eating, it doesn’t extend any trip by much.

I still have a gas vehicle but I never want to use it for long trips.

In my only attempted road trip with my EV, the only charger available within any reasonable distance of our destination failed to charge the car due to a "firmware issue" that they had been aware of for quite some time but did not bother to fix. We were unable to charge there. Luckily, we had enough juice to make it back to the charging station at our halfway point by turning off the climate control.

So on a road trip that I only wanted to charge twice for, one of the stops didn't work. Oh, and on the way back we had to wait for access to the faster charger. Maybe not so overblown.

Yeah my concern with charging is more time and effort to get it to an open working charger than it is charge time.