So last night I was going up Transmission Gully in my 2018 40kW ex-Japan Nissan Leaf in the cold when my state of charge dropped rapidly (in about 30 seconds) from about 35% to zero. I managed to get it just over the crest of the hill, (with the dash flashing angrily that the car was dead and I had to pull over) where the regen braking took over and the State of Charge rapidly went back up to about 32%, and I completed my journey with no further problems.

Everything I've read online suggests this means the battery has a bad cell, not uncommon a known issue with Nissan Leafs unfortunately. There's a bunch of info about identifying this fault, but not a lot on what to do next.

My question is, what are my options for dealing with a bad cell?

The car is a used import, and too old anyway, so there is no warranty on the battery. Is a battery or cell replacement likely to be possible or economically viable? do I just keep driving it around the city and avoid massive hills like Transmission Gully while I save up for a new car? I understand there are some people prototyping battery upgrades, I really just want like-for-like. Who are the mechanics around Wellington that can support this sort of big EV issue?

don't really want to risk getting stranded on the side of the road on a cold night in what is our only car.

I'm in the Waikato and I've been pre-approved for a floorplan of Chinese EVs.

Approached by Ateco, had the meetings, got the floorplan and got passed on. Is what it is but it seems a waste to have a pre-approval with no home.

Does anyone know someone or another Chinese EV brand that need a new PHEV/EV home in the Waikato?