Kia Niro UK Forums

I believe that the American version of the Niro does not have a separate 12v battery, but has a bit of the main lithium battery as a 12v auxiliary battery. That explains the differences noted in the emergency responder's document - which was for the US model. On that model, you can recharge the auxiliary 12v battery from the main battery by pressing a button (sounds as if someone was expecting the 12v battery to discharge!).
@h2onorth, yes I did lose the radio settings the second time that the 12v battery went flat, although not the first time.
I knew where to jump start the car because the first time the battery went flat I called out the RAC, and the guy knew exactly where to put the jump leads. The second time it happened, I had got the jump start battery so was able to get going by myself.

Kia Customer Services have confirmed that UK niro's from Model Year 18 will have the 12V battery as part of the main Li-ion battery under the rear seat.

Just realised my battery booster under the front seat was right up against the heater/air vents. Move it as close to the door as possible.