batteries sure don't like the cold

  • Fri 20 February 2015
  • misc

I just got my Leaf back yesterday. It spent the last week in the body shop, having fallen victim to a mishap while parked.

Unfortunately, it spent the last week being cold-soaked in our near-record temperatures and not being plugged in.

The battery gauge read 55% when I got it back, and notably lower "mileage" on the economy meter than when I dropped it off. I'm guessing it spent some time in the "on" position. No harm no foul, but I didn't want to risk running out of juice on the way home with Kim out of town and not able to rescue me.

So I dropped by the Nissan dealership and fired up the CHAdeMO DC fast charger. By the time I got there the battery had dropped to 35% so perhaps it was a good idea to err on the side of caution. I've seen these things dump power in at a truly frightful rate, as high as 106 amps at 391 volts when starting out, and then taper off as the battery pack gets full.

Yesterday was not one of those days. The CHAdeMO charger talks to the CANbus in the car, and adjusts its output based on what the car can take at any given time, which includes the temperature of the battery pack. It started out at 391 volts @ 45 amps (about 3x what I could get with the Level 2 charger) but over the course of 20 minutes tapered off to 20 amps, which is maybe 20% better than I could be getting from the built-in charger at home.

Made it back to the house fine. Not even into the backup heat this morning despite it being 2 degrees out at dawn (no wind makes a difference)