NHTSA Complaint #11557509 — 2020 NISSAN LEAF

I was driving on Interstate Highway H-3, uphill at 55 mph, when the % charge on the high-voltage battery instantaneously dropped from 18 to 5%. The warning light also came on. I was not using the A/C at the time. Over the next 30 seconds or so, the gauge quickly went from 5...4...3...2....1. By dumb luck, as the gauge hit 1%, I hit peak elevation on the mountain pass, and was able to coast in neutral until the freeway starts going downhill. Normally, an 18% charge would have been more than enough to comfortable complete my trip home from where I was on H-3 at the time. A sudden drop in battery % could lead to a cutoff of the motor, which at high-speed on a highway could cause a serious accident. I have subsequently done a battery health test and found the State of Health rating to be 90%. There don't appear to be any bad cells in the battery that would explain the sudden drop while driving. My hunch is that this problem is related to the firmware update I received at the Nissan dealer to address NHTSA Campaign Number: 23V494000.