Range vs Fast Charging

[bwilson4web]

Nikki of Transport Evolved poses an interesting question a 3:55 in this video:


Can shorter range be compensated by faster charging?

Owning a BMW i3-REx, the EPA specs are:

• 72 mi EV - ~30 min to charge, 50 kW, including taper
• 78 mi gas - ~5 min to refuel, 2 gal

I've driven 700 miles, 10 refuelings, in typically 1h 15m segments. I cruise on the highway at ~70 mph but with frequent stops, the average speed is lower. Actual refueling includes a ramp down and ramp up. Also, we prefer to have a little gas in reserve:

• 72 mi gas @70 mph: 1h 2m
• 3 mi gas @35 mph: 0h 5m
• 0 mi gas @0 mph: 0h 5m
• 72 min = (1h 2m + 0h 5m + 0h 5m) ... 1.2 hr
• 60 mph = 72 mi / 1.2 hr

Now we can do the same cycle with the standard, 30 min recharge at 50 kW. This is much easier as we only have to change the time by adding 25 min to the existing 5 min refueling:

• 44 mph ~= 72 mi / 1.62 hr

Let's change the recharge time to 15 min at 100 kW. Now we only need to add 10 min to the 5 min refueling:

• 53 mph ~= 72 mi / 1.37 hr

Now let's try doubling the EV range yet keeping the original 50 kW charge rate:

• 151 mi EV @70 mph: 2h 10m
• 3 mi EV @35 mph: 0h 5m
• 0 mi recharge: 0h 60m
• 195 min = (2h 10m + 0h 5m + 0h 60m) ... ~3.3 hr
• 46 mph ~= 151 mi / 3.3 hr

I think Nikki is right that charging speed is the critical factor on increasing the EV cross country speed.

Bob Wilson

 

[Calliope]

I honestly don't understand the numbers in your post, but doesn't frequently using fast charging decrease the life of the battery? Now, you (or I) might not care about that, but I think it should be taken into consideration.

 

[bwilson4web]

It probably eats into the charge cycles.

Bob Wilson