Battery completely dead after I just charged last night???

[DSlack73]

So I charged my 2015 focus yesterday evening , this morning 530am I went down and moved it half a block so I wouldn't get a ticket . I hit the lock button once on remote heard it lock before I walked awAy . I go to leave 8 pm and nothing . Completely dead dead . I discovered the hidden key on remote while checking for a dead battery in remote ,lol . I was able to get in a d try the power button , nothing. If i forget to turn something off when getting out of vehicle , when I would hit the lock button it would beep 2or 3 times so I would check. But that didn't happen this morning . I will probably have it towed tomorrow to a charging station. I have a 3 yr power train warranty I wish they would just put a new one in.

 

[Anti_Climax]

That sounds like a dead 12V battery, a charging station won't help.

 

[Heima]

So your remote battery is dead? Or the 12V battery is dead? The only way to loose the HV battery charge over night would be to leave the climate control on.

If the 12V battery goes dead, the car acts crazy.
If the remote battery is dead, you can put the remote onto the special spot in the center armrest.

 

[Dave st.peter]

So your remote battery is dead? Or the 12V battery is dead? The only way to loose the HV battery charge over night would be to leave the climate control on.

If the 12V battery goes dead, the car acts crazy.
If the remote battery is dead, you can put the remote onto the special spot in the center armrest.

On my 14 the rest or fob home is under the key start plug.

 

[Northwest_Greg]

The first time this happened to me was the morning of the day after i purchased the FFE (a 2013.) Apparently, the dealer found the 12-volt battery dead when they were preparing the car for my test drive. They jump started it and let me go on my way. I used the entire HV batteries' range to get home and put it on an L2 charger overnight. The next morning it would not unlock via the remote and thinking the remote needed a battery replacement, I discovered the hidden door key which gave me access to the hood release. I was surprised to find a 12-volt battery under the hood, so I tested it and found it low on voltage, a jump start got it working. Called the dealer and they were apologetic and offered me a new battery if I could install it myself (that is the easy part.) Nowadays I keep a small jumpstart device in my glove box because occasionally, in hot weather the computer starts the AC system and lets it drain the 12-volt battery. Once I restart it with the jump and let it sit "ON" or begin to drive it around, the HV battery recharges the 12-volt. The 2013 owner's manual says it will do this in only 10 minutes.

 

[SirStorm]

There is a TSB from Ford about this, it requires a new Telematics Module and updated programing to that module. Trouble is, the module is unavailable with no projected production date. Basically Ford has abandoned us but doesn't have the guts to make that public. My solution was to install a voltage monitoring disconnect on the battery from Amazon. The 12 volt battery that is required to run all the controls and stuff that any normal ICE car runs with 12 volts IS NOT charged by the plug in charger for your High Voltage battery. There in lies the issue. When the Telematics Module goes haywire, it drains the 12 volt battery randomly. My solution does not prevent that from happening, but when the battery drops to 12 volts the battery cut out activates disconnecting the battery from the car (a normal healthy battery is 13.2 volts at full charge). You lose your presets and programming but it allows you to then activate your battery and start the car. The solution I chose has a remote button so you can activate it outside the car then use your remote to open the door and start the car. Once started, the car will then charge the 12 volt battery and you will be good to go for another random amount of time (could be months, could be days).

 

[Anti_Climax]

occasionally, in hot weather the computer starts the AC system and lets it drain the 12-volt battery.

The 12V battery doesn't charge from the plug on it's own, but while the HVDC contactors are closed (which is the case during AC compressor operation) the DC/DC converter is feeding 12V just like an alternator would.

I've found that the 12V level droops in the heat and goes below the threshold the vehicle considers acceptable. Which is fantastic, because I'll remote start, it will do so successfully, start providing good/correct low voltage DC that can top up the battery and then it will register the "bad" voltage and shut down anyway. Best I can tell, they didn't bother changing the behavior from the ICE version so it cuts off to ensure you have enough for a "real" start.