Someone correct me if I’m wrong, but 12.1 volts seems pretty low. A fully charged 12 volt battery at rest should be about 12.6 to 12.7 volts. When you get down to 12.2 it is 50% discharged (give or take). Try having someone jump you or put it on a charger for a while. 12.1 volts might be enough to run the lights and radio but maybe too low to start it up. If it can’t hold a charge of 12.6 volts overnight, you might need a new battery.
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2008 Liberty Sport 4x4 Automatic
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AtTheHelm Front Recovery System & Roof RackM116A3 Trailer build thread: viewtopic.php?f=72&t=77997