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After dodging the dead 12vt battery issue for 2 years...


shaggy314
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I've got a battery tender which could be employed pretty easily. The 12v battery isn't hard to access.

Connect the battery tender to the terminals under the hood.  If you connect directly to the battery the computer will not be able to measure the charge being put into the battery.  Plus there is a slight risk of an explosion if any hydrogen has accumulated in the battery compartment.

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If the car sits for a week without being used there will be problems with the 12 volt battery.

At least for my 2014, this is exaggeration. May be problems. Not will. I've had the car sit for two separate instances of more than a week without being plugged in, checking it an average of once every other day with mfm and without any 12v issues. Currently my vehicle is coming up on four weeks without a full charge (one part charge to bring it back to 60%) and having only been idled long enough to provide some charge the 12v twice.

Edited by openair
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At least for my 2014, this is exaggeration. May be problems. Not will. I've had the car sit for two separate instances of more than a week without being plugged in, checking it an average of once every other day with mfm and without any 12v issues. Currently my vehicle is coming up on four weeks without a full charge (one part charge to bring it back to 60%) and having only been idled long enough to provide some charge the 12v twice.

Is your car an SE? Does it have keyless entry?

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Connect the battery tender to the terminals under the hood.  If you connect directly to the battery the computer will not be able to measure the charge being put into the battery.  Plus there is a slight risk of an explosion if any hydrogen has accumulated in the battery compartment.

Explosion bad. Well maintained 12V battery good. I've located the under hood terminals already from pics in another thread.

 

Out of curiosity, why would I care if the computer knows what the 12V voltage is, as long as it is charged to full? Won't it remeasure it in real time, or sometime during the startup process itself maybe even?

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Explosion bad. Well maintained 12V battery good. I've located the under hood terminals already from pics in another thread.

 

Out of curiosity, why would I care if the computer knows what the 12V voltage is, as long as it is charged to full? Won't it remeasure it in real time, or sometime during the startup process itself maybe even?

It monitors the current flow into and out of the battery to estimate its charge level.

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It monitors the current flow into and out of the battery to estimate its charge level.

So it estimates the charge, rather than having an ability to measure like I do when I use a voltmeter to determine it in real time? Well that sounds fairly bizarre. It would seem that with all the sensors and electronics and the outright necessity for the car to know the condition of the battery that allows the entire system to start up that it would just measure the thing to be really, really sure about it, rather than just guessing based on some algorithm. 

 

After 60 miles of driving today in EV Later mode to make sure I was running the ICE and getting a better feel for what the real world fuel mileage might be when operating in hybrid mode (the mode I plan on putting the most miles on it in), I checked the 12V again and it sits at 12.26V. 

 

Haven't charged the HVB in a few days, have been carrying about 20% SOC on the grounds that I would rather the battery operate within a higher SOC window when it does the hybrid cycling routine (plus I wonder if never fully charging or discharging the battery within even the window already built into the control software) is a good thing.

 

Anyway, EV later mode is getting me 45-55 mpg in mixed interstate and good sized secondary roads, 50% A/C use, will get a in cabin voltage measurement device for the cigarette lighter before the first big road trip.

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So it estimates the charge, rather than having an ability to measure like I do when I use a voltmeter to determine it in real time? Well that sounds fairly bizarre.

 

The sensor not only measures the current battery voltage, which is only a crude approximation of the charge, but the current going in and out of the battery over time. In theory that should provide a better measurement, no idea if it actually does or not, depends on how well it's implemented. Looking at what the Body Control Module says the state of charge is on mine, I have my doubts. I have a feeling that it doesn't actually read the sensor if the car is charged by an off-board battery charger, possibly because the BCM is sleeping.

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You cannot reliably measure the SOC of a battery under load by measuring the voltage.  When the car is running, you have to keep track of SOC by measuring the current flowing into and/or out of the battery.  The car will recompute the SOC of the battery by measuring the voltage after the battery has rested with no load for a few hours.   If you are going to measure the SOC of the battery using a voltmeter, the car must be turned off and you need to wait 20 minutes or so for the car to turn everything off and for the battery to reach chemical equilibrium. 

Edited by larryh
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So as another information point, starting with the HVB at 0 miles on the dashboard, about halfway through the HVB charging cycle I checked the 12V battery, it registered 13.35V. So I assume it is charging during the HVB charging, one way or another. Next I figure I'll catch it right after the HVB is finished, although when I caught it just as it finished the last time I went out to the garage and checked the amp pull on the Kill-A-Watt and it wasn't pulling any more than normal than it does when keeping the green light on. I figured if it was charging the 12V battery after the HVB was full, I would have seen at least 0.5 amp being pulled to do it, but it wasn't there.

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Technically, my car didn't exhibit any of these problems, so there was nothing to really troubleshoot.  Others on the forum have said that they will not update a module unless they have a reproducible problem, in which case they could update it under warranty.  Asking the dealership to just arbitrarily update the software is what I did.  I just consider it computer maintenance.

 

It was just stupidly expensive.

 

To get access to Ford's calibration files for 1 year is $699, and that doesn't include any hardware.

Russael,

 

When you go to https://www.etis.ford.com/vehicleRegSelector.doand look up your car does it actually show all the modules updated? See picture. Wasn't sure if that website is updated accordingly.

 

I did the recall for 15E03 - POWERTRAIN CONTROL MODULE REPROGRAMMING but the date checked is the same as the others/build date time frame.

post-450-0-15132900-1438712412_thumb.jpg

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Purchased a voltmeter/ammeter to use in the cigarette lighter (got two of them actually, one blue LED, one red, red works better in daylight). Looks like the 12V system runs 14V+ for awhile while EVing around town, then drops off to 13.3+/- after awhile (I assume some small amount of charging took place previously?),  didn't see it drop back into the 12's until I turned the car off, which sounds about right. 

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  • 4 weeks later...

Last summer my car sat for 2 weeks not on the charger in the garage while I was away. I lost maybe a mile of range while it sat there. I put it on the charger when I got back. I've since learned to delay charge the car so it doesn't spent a lot of time at full charge.

 

I see the car will from time to time sit charging at 60 wt for 10's of minutes after a full charge to top off the LVB.

 

Since we have the service notices posted here, you can really game the system by using the phase in the bulletin as to the symptoms. I've had my local Ford go either way reproduction vs. customer complaint of issue, so it is your service manager making the call as to do it or not.

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