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Disclaimer: DO NOT TRY THIS (Go to your dealer to resolve any issue with your car involving malfunctioning equipment). There are times when I might want to "reboot" the electronics on my Ford Fusion Hybrid (2017). The 12V battery is in the trunk (see picture). Under the hood are (+) and (-) "prongs", specified by Ford (in the manual) to be used to jump the car (page 229). This is needed since you can't open the trunk of your car without the 12V battery -- which is in trunk(!). Explain that to your old man. What is the best way to disconnect your 12V battery? I did it by loosening the nut labeled "A - Negative Side" on the photo. The "washer" under the nut made an unsettling "crackle" sound (as it formed a circuit on and off a few times -- was I"frying something"?) This worked. The car was disconnected from 12V and solved a problem. Attached are some reference 12V battery pictures from my 2017 FFH.

I tend to leave my car for a month unused while traveling 2-3 times a year and am worried about killing the 12v battery. I've seen mention about people using solar chargers (smart chargers so it doesn't over charge) and was wondering if anyone has any brand recommendations or success stories? Should I hook it up to the trunk battery, or the front hood terminals? Other that potential hydrogen gas buildup when doing the initial hookup in the back, any reason not to wire it up there? Am I correct that the HV battery charges the 12v ONLY when the car is started and running? So I don't have to worry about killing the HV batteries if it sits? Any downsides to this? Thanks!

I've had my FFH-SE for almost a year now and have put about 5k miles on it. Its a 14' with 75k miles. Everythings been fine except its been acting a little strange sometimes. Occasionally when I'm parking the vehicle (I always use the parking brake) I come to a stop, put the vehicle in park, activate the parking brake, and turn off the vehicle. After that last step, sometimes the car will completely power off and will not enter retained accessory power mode (ie radio and windows still working). If this happens I usually start the vehicle again. When I do I notice that my settings are back to default and the AM radio is on. Also the start-up chime sounds old (the "duu-daa-dum"). And a message will pop-up saying theres a parking brake fault and to get service. I disengage the parking brake and everything fine again. Another time I was putting washer fluid in and I left the driver door open. After I finished checking fluids and such I came back inside the car and notice that everything was off. Like everything. After slight panic of not even knowing how to open the trunk in this situation (to access the 12v batt). Everything came back on and was on default. Other times I will start the vehicle from a being away from it for 8 or more hours and the wrench light will come on as soon as I start it (has only happened twice). I can usually get the wrench to go away by cycling the power a few times. Anywho all of these things have been happening in the past few weeks. Now that I've wrote this all down I feel the 12v battery may be the issue so i will get that tested now. But does anyone have anything to add?