The 2016 cars all have an auxiliary 12v battery.
This battery is critical in making your car run. Example if this battery is not fully charged, your car won’t even turn on. This 12 V battery gets charged when the (key is on) The DC to DC converter takes 48 V from the cars traction battery and converted to 12 V and charges the onboard 12v aux battery. It also charges the auxiliary battery when the car is plugged in to it’s 220 V again threw the DC to DC converter.
Well, what happens when your car is fully charged and you leave it sit for two weeks.
Well, I can tell you you come back to a dead car! Not wanting to leave my car plugged in indefinitely I came up with this idea.
I got two small trickle chargers and ran them to each of the 12 V batteries in my car
Then so I could see the voltage in each battery I installed a USB volt meter’s one for each battery.
Then I installed a 110V charge port to the front of the car.
So now I can comfortably leave the car sitting for extended time, and no, I’m not going to come back to a dead car.
These inexpensive USB voltmeters can be turned off if the blue light is bothersome