Solar trickle charge

[edicito]

I understand that the cigarette lighter might not work with my solar charger because it shuts off shortly after shutting off the car. My question is whether the cigarette lighter can be recoded so my solar charger keeps the battery strong while I am traveling.

 

[alohart]

Your i3 has a large HV battery pack that maintains the 12V battery, especially while traveling. There's no need to try to charge its 12V battery with a solar charger except if your i3 were parked for more than a month. However, as you noted, the auxiliary power ports shut off shortly after turning an i3 off, so this wouldn't work. I've not read of anyone successfully coding the auxiliary power ports to always remain connected.