I had this issue months after purchasing the car back in 2020. It was under warranty, so I had the battery replaced. It happened again today in January of 2023! The car was running fine the day before, and this morning it wouldn’t start. Battery showed 8V, so it drained overnight. Just had the car towed and the tow truck driver said this happens all the time. Every two years expect the battery to die. I haven’t seen a recall from Ford or any solutions for this problem. I’m looking into replacing the 12V with an Optima battery.
Suggest to not depend on that diagnosis. Most likely causes are either the 12 volt battery isn’t being charged properly (hybrid control-system problem), or 12 volt battery is draining overnight b/c something remains turned on. After you park, doors/windows closed, everything “off”, wait for a couple of hours, go back out and check if any lights are on, brake lights, glove compartment, interior, trunk, engine compartment etc.
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I have had 2 Fords that ate batteries. One because of a weak alternator and tne short trips we were taking. The second because of heat. The battery would be fine to drive to… but an hour later, nothing. No lights, no crank, could not be jumped. If you live where is is hot most of the time… Florida, Arizona, Texas, it IS normal. Buy 36 month batteries with no pro rated life.
If the tow truck driver says its normal… it is because the driver has towed a LOT of these cars.
Hey all - I have a 2019 Ford Fusion Hybrid Titanium with about 51k miles on it. I’ve been through four 12v batteries in the past two years and the fix I finally figured out on my own was to fully turn off everything FordPass related. In the infotainment screen in your Fusion (aka Sync3), go into the settings and turn off FordPass. I also deleted the app and removed my car from the app as well. Since I did that, no more issues. One other thing last year was that my glovebox light wasn’t turning off even if the glovebox was properly closed so I manually disconnected that as well.
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Thanks for the info.
Most don’t realize these cool accessories and features require power from the battery.
That’s pretty interesting. I didn’t know Ford made something like FordPass. I know someone with a Ford Fusion PHEV that’s been pretty reliable with no issues(no FordPass). All that’s wrong with the car is poor mileage after charge so he doesn’t use the charger at all.
Because of that car, I learned that PHEVs are a no go. Regular hybrids are way better.
Poor mileage determined how? Calculation… miles driven divided by fuel used? Or the display?
A plug in hybrid should significantly improve the fuel economy. If the car is only driven a few miles a day, the gas engine may never turn on… so no gas used, only electrons.
It seems like he charges it all night only to get like 10-15 miles out of it, if that. It seems like the reported mileage range and the charge time don’t match up and doesn’t seem to be worth the hassle of plugging it in every night.
Because of that, I vouch for full hybrids all day instead of plug ins.
Plugging the car in is a hassle? To save 2 or 3 bucks in gas? Every day? And when the battery runs down the engine just starts up automatically… Yes that is an amazing hassle. It is no wonder your friend doesn’t plug it in. 
Most plug in hybrids get more miles in EV mode than that.
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Yup! The amount of misinformation that is floating around on this topic is monumental. However, I won’t claim that a PHEV ist for everyone. Obviously, if someone can’t do charging at home, its practicality suffers. And, if someone is too dense to remember to charge when appropriate, then a PHEV probably makes zero sense.
For the record, most of my driving is done in EV mode, for which I now have a 57 mile range. When first delivered, it had the mfr’s specified 37 mile battery range, but as owners find out over the ensuing months, that range slowly builds.
Because most of my daily/weekly errands are well-within that 57 mile range, I rarely have to engage the IC engine. And, depending on my usage, I don’t always need to recharge every night.
When I go for a longer drive–as I did yesterday when I drove about 90 miles roundtrip for apple picking–I drive in EV mode until I get to the Interstate, and then I switch to HV mode, which uses the ICE and the battery alternately, depending on driving conditions. Once I’m off the Interstate, I go back to EV mode. The gas mileage when in HV mode varies greatly, depending on how much of my drive was done on battery and how often the IC engine ran. So far, my mpg in HV mode have ranged from a low of 42 mpg up to 70-something mpg.
I got the vehicle on 11/10/22, and from that date to 9/28/23 (the last time that I put any gas in the tank) I drove 7,909 miles, and used 52.07 gallons of gas–in total–to drive almost 8k miles.
If someone is curious, then he can calculate the overall mpg, based on that amount of gas and that number of miles. I know what the figure is, and–needless to say–I’m very pleased with it.
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Yeow! That is some mpgs!
Yes, I am very satisified with its overall economy.
And, I am also very pleased with its power. There are those–like you–who are aware that an electric motor puts out its maximum torque from the get-go, giving it very impressive acceleration. Then, there are those who think that an EV (or PHEV) is “slow”.
Obviously, flooring the accelerator uses-up a lot more energy, and shortens its range–just like with an IC engine–but it is… let’s just say… amusing to watch the facial expressions of drivers who decide to try to out-accelerate my PHEV from a traffic light.
Yes, I can still be somewhat teenager-ish, even at my advanced age. 
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1000 to 1500 hours is a typical battery life in a hot southern climate with a traditional 14.4 Volts all the time charging system. Newer cars tend to have better charging and reduce the charging Voltage as the car warms up so it shouldn’t happen.
Check for over charging and over discharging. If frequent over discharging can’t be helped, then buy a deep cycle battery and don’t let it freeze and it will last a lot longer.
Are you sure it wasn’t just the glovebox light causing the problem>
I hoped it was just the glovebox light but I disconnected that last year and still had 12v battery drain issues a year later. My friend who works at Ford said there’s so many systems that never properly shut down and that it makes sense one of those is the FordPass system since it’s always trying to communicate with the FordPass app on my phone and to whatever else it’s connected to.
Lol yes that’s what I’m saying. It doesn’t seem worth it at all.
That said, the vehicle is around 2014. So the batteries arn’t working at 100%. I think if the components were working better than it mightve been worth it. But 2014 isn’t that old imo.
Oh yea, the FordPass system allows the vehicle: “With FordPass Connect, you’ll enjoy access to exclusive remote features like starting and stopping your engine, locking and unlocking your doors, locating your vehicle, and checking vehicle status - all from the convenience of your smartphone. You can even keep tabs on your vehicle’s fuel level and oil life with the tap of your finger.”
So basically it never shuts down because it always has to be “on” even when the car is off in case you access the car with your FordPass app on your phone. It’s quite hands to remote unlock your vehicle or remote start it before you’re in range to do so with the key fob. But I’d rather have my 12v battery not die then have those convenience features. Not worth the trade off.
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Is this only available on the higher trims?