[Porchdog]

Assuming that Jeep has auto start/stop - you drain the starting battery at every light. Even worse with the radio, lights, A/C, navigation...

If you are making short local drives with lots of stops, you can end up with less battery charge than you had when you started each trip.

The other thing I have seen in newer cars with keyless entry and key less start - they are constantly scanning for the key fob. That takes a non-trivial amount of power - especially over a period of weeks. Many of them (like my wifes Buick) start a pump when the key gets close, or even turn on interior lights and fire up the dash and connect bluetooth, in anticipation you will get in.

Two or three weeks without being started shouldn't be an issue even with all the above - but with certain modern cars, it seems to be. Combine that with a starting battery (or both batteries) that rarely or never got to full charge after leaving the dealers lot - those batteries can easily get discharged.