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slow DCFC in winter

Posted: Fri Nov 10, 2017 3:44 pm
by specialgreen
In August, at about 70F, I was charging at 12.9 watt-hours/second doing DCFC. Yesterday at 16 degrees F, I was getting 5.75 watt-hours/second at the same charge station. The amount I can charge in a half-hour appears to have dropped from 23kw-hrs to 10.

Re: slow DCFC in winter

Posted: Sat Nov 11, 2017 7:20 am
by GerryAZ
Internal resistance of battery is higher at low temperatures so lithium battery controller (LBC) limits maximum charging current to keep cell voltages below the maximum allowable. The LBC also limits regeneration for the same reason.

Re: slow DCFC in winter

Posted: Mon Nov 13, 2017 10:17 pm
by specialgreen
Would charging at the end of the commute help? I had gotten into the habit of DCFC charging every other day (my commute is only 14 miles). I'm not surprised to see charging slow-down, but 57% slower? Yowza.

This reminds me that I saw a used Leaf on Craigslist, and the previous owner said he'd added a battery warmer. If I were driving, and knew I was headed to a DCFC in 10 miles, I wouldn't mind using some juice to warm the battery into a state where it would accept a fast charge.

Re: slow DCFC in winter

Posted: Mon Nov 13, 2017 11:38 pm
by LeftieBiker
That was likely a 2011 Leaf, and the warmer was added just to protect the battery from freezing.

Re: slow DCFC in winter

Posted: Thu Nov 16, 2017 3:30 am
by arnis
With cold battery having lower state of charge helps to speed up quick charging.
Visiting DC station at 10-20% would be perfect.