Question on battery heath vs. range vs. kapa

[Chris94]

Hello,
New to posting here, but have found the forum to be very helpful as I look for a used i3.

I am looking at a 2017 Rex that was purported to have "very good" battery condition. When I went to test drive I was a bit alarmed to see the battery bar showing Full and a battery range of only 54 miles. I test drove a few miles and the range figure dropped accordingly. The car had been in a cold environment (10 degrees F, -12 degrees C) for a couple days. Following the drive the car was parked in a warmer (well above freezing) parking bay while I inspected the car. After a while I noticed the range increasing to 74 miles just sitting there with the car turned on most of the time. I had to leave, so I couldn't verify if the range would go even higher.

I found the kapa to be 28.1 kWh, which seems to be a pretty good value, but I have read here that kapa isn't everything when it comes to battery condition.

When it's cold, does the range improve after driving for a while as the battery gets to its ideal temperature? So, if I set the car to be ready at a certain hour, will it warm up the battery in advance? I don't want to have 50 miles of range, so I'm hoping I can get some insight from this group.

Other than this issue, and a damaged plastic jack point insert, the car drove well, despite having ecopia tires (I have already arranged for a set of blizzaks on spare rims if I buy the car.)

C94

 

[mojo]

When it's cold, does the range improve after driving for a while as the battery gets to its ideal temperature? So, if I set the car to be ready at a certain hour, will it warm up the battery in advance?

Provided you don't need to exploit any EV-specific electricity supply tariffs then yes. If you are able to plan for your charging to complete just before you are due to leave then the battery will already have been warmed a little by the charging process (the degree of heating depending on the rating of charger that you use). That effect can be augmented if you set the car to carry out "battery preconditioning", which is where it uses power from the EVSE (charge point) to warm up and maintain heat in the battery during the 3 hours before your departure time.

Also, as you've already noted, if you are able to store and charge the car inside a garage that will help too, slowing the rate at which the battery cools after charging, and reducing losses to the surroundings while preconditioning is under way.

Unfortunately many EV-specific electricity supply tariffs completely preclude battery preconditioning, because of the rather limited design of charge scheduling that BMW saddled the i3 with. It's a price that some of us have to pay for cheap overnight electricity.