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Joined: Mon May 21, 2018 9:28 pm

Drained 12V Battery

Mon May 21, 2018 9:44 pm

I recently purchased a 2014 FFE. My 12 volt battery keeps draining, leaving the car inoperable until jumped. I took it to my local dealers service dept (They knew very little about ev's) They had to bring a guy over from another shop, who was experienced. He went through the car with a fine toothed comb, and couldn't figure out why it was draining. (I had them check the battery, and it was ok).

I thought maybe a program I had experimented with on MyFord website might be running the heater. But, negative on that as well. Now, someone else, somewhere, has had this problem also, I'm sure. Does anyone have any insights?

Posts: 535
Joined: Fri Sep 26, 2014 10:20 pm
Location: Southern CA

Re: Drained 12V Battery

Tue May 22, 2018 5:06 pm

I had this 12v battery draining problem early on the first year with my leased 2014 FFE.
However a firmware update came out that reportedly addressed this problem among other things and I go that done at the Ford dealer and I rarely had the issue after that.

To be safe, I kept a lithium ion 12v emergency starter battery unit in the car and had a Sears 12v car battery charger I kept in my garage, to get the 12v battery going again quickly if it every happened.

Replacing the 12v battery won't stop the problem from happening, but is recommended if the battery got fully discharged too often.
2014 Ford Focus Electric - Oxford White, Cloth Seats (Lease ended 9/28/2017)

Posts: 1100
Joined: Tue Aug 16, 2011 11:40 am
Location: Toledo, Ohio

Re: Drained 12V Battery

Tue May 22, 2018 8:52 pm

This thread will have all your answers: http://www.myfocuselectric.com/forum/vi ... =14&t=3812 Basically what happens is one or more modules does not go into sleep mode when the car is turned off. Ford in their infinite wisdom designed the car without a way to troubleshoot this in the event that the problem is intermittent. The only way to troubleshoot it is to catch the misbehaving module in the act of not shutting down. This is done by measuring the current draw on the 12V battery 40 minutes after turning the car off. This delay gives everything time to shut down into sleep mode. The ford spec is that there should be no more than a 50mA draw. FWIW mine measures at 20mA. If it's more than 50mA you literally have to start pulling fuses until the current drops to find the bad module.

Simply buying a new battery to "fix" the problem is a waste of money. The new battery may be strong enough to not be drawn to low to start the car for a few months, maybe even a year. However this will ruin the new battery and you will have to prematurely replace it and you will still have the problem. There that's the Reader's Digest version of the thread linked above. :D

Edit: Depending on your situation, under normal usage for some reason the motorcraft batteries tend to only last about 3 years in the FFE so you may have simply reached the end of life of your battery.
2014 Blue Candy FFE
http://www.fuelly.com/car/ford/focus/2014/triangles/303811 (since this forum doesn't allow BBcode in sigs)

Posts: 2
Joined: Mon May 21, 2018 9:28 pm

Re: Drained 12V Battery

Wed May 23, 2018 6:16 am

Thanks, all! This has been very enlightening. At least now I feel as though I'm on top of the problem. I will check the level of software/firmware updates on my vehicle. Remarkably, I had just purchased a back-up power supply, so I can jump it myself, just in case. Thanks for the expertise, guys.

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