Install a Battery Voltage Meter - Must have

[kaptnk228]

We are now one of the new members of the Ford C-Max Hybrid dead battery club.  There is no battery monitoring system (BMS) on our C-Max 2013 that works.  Failure of the battery at highway speed could end your life as you lose steering and brakes, air bags.  At 5 mph I had a hell of a time stopping the car!

 

I REPEAT.  FORGET ABOUT MPG'S FOR A MOMENT.  IF YOUR 12 V BATTERY DIES YOUR CAR DIES PERIOD.  IF THIS HAPPENS ON THE HIGHWAY THEN YOU MIGHT DIE LIKE ALL OF THE 31+GM OWNERS WHO HAD THE FAILED IGNITION SWITCH.  PROTECT YOURSELF.

 

Buy a volt meter from Amazon for under $3.00 that you can plug into the 12 Volt  cigarette socket.  A fully charged battery will read 12.8 Volts+  A charging system voltage will be at least 13.5 to 14.5 Volts.  Use it regularly until Ford fixes the system.  You will have piece of mind and a great way to monitor your car's battery.  A dead battery will read 12 Volts that is what we had when the battery monitoring system kicked in 10 seconds before the car died, losing brakes, steering, flashers and everything else.  Be prepared to use the emergency parking brake.

 

Check your battery voltage daily until you get the meter.  Buy a regular volt meter and check the system's voltage by using the two terminals located in the front right side of your vehicle.  One is + and the post is -   You NEVER know when the charging component will or has failed.  That is one of the big silent problems.  You just don't see it coming.

 

Send a letter to Ford to first fix the BMS and second to add a visual voltage meter  and Coolant Temperature gauge on the Left side of the panel (available in My View).  They should also add parallel redundancy to the battery charging system with at least 3 systems and to redesign the system so that the car will not die once started if the battery dies.

 

We live in Canada 50 miles from where this car was built but we are a 3rd world country to Ford.  Write Ford USA.  They can ignore me but not the USA citizens. 

 

Battery (12 v) failure MUST NEVER SHUT THE CAR DOWN WHEN BEING DRIVEN.  NO POWER; NO POWER STEERING, NO POWER BRAKES, NO LIGHTS/FLASHERS AND MOST LIKELY NO AIR BAGS.

 

If you do not see the battery being charged while operating the vehicle contact your Ford Dealer ASAP and perhaps don't drive the car.

 

I am trying to warn all C-Max hybrid owners of this problem.  We had the most recent upgrade done on October 23 2014 when our Navigation System was repaired, one day before the battery died.  Ford tech's did not notice that the charging system was not working because no alarms were showing.

 

The C-Max hybrid is different than a standard car.  The ICE (engine) does not have a starting motor or an alternator.  The EV motor starts the ICE.  The Li ion high voltage battery charges the 12 V system.  The 12 V system runs things like the radio, standard instrumentation and I believe the air bags.

 

UPDATED 7 Nov 2014

 

Found dc/dc charger for battery was not working ......No Alarms

Found high amp fuse with very heavy wire was replaced and solved the problem - it must have be shorting out putting a drain on the charging system and emptying the battery.

 

Still not BMS update.  You can access the charging system voltage and coolant temp via the ETM mode at startup.  Suggest check regularly until you get a voltmeter and Ford fixes this end of the problem.

 

It took 2 weeks but our C-Max is up and running - charging voltage is normally 14.3-4 Volts.  Note: 13.4 V or so might indicate the fuse problem as was in our case once the Dc/Dc charger was replaced.  Check the battery light is green located on top of the battery and very difficult to see.

Edited November 8, 2014 by kaptnk228

[ptjones]

We are now one of the new members of the Ford C-Max Hybrid dead battery club.  There is no battery monitoring system (BMS) on our C-Max 2013 that works.  Failure of the battery at highway speed could end your life as you lose steering and brakes.  At 5 mph I had a hell of a time stopping the car!

 

Buy a volt meter from Amazon for under $3.00 that you can plug into the 12 Volt  cigarette socket.  A fully charged battery will read 12.8 Volts+  A charging system voltage will be at least 13.5 Volts.  Use it regularly until Ford fixes the system.  You will have piece of mind and a great way to monitor your car's battery.  A dead battery will read 12 Volts that is what we had when the battery monitoring system kicked in 10 seconds before the car died, losing brakes, steering, flashers and everything else.  Be prepared to use the emergency parking brake.

 

Check your battery voltage daily until you get the meter.  Buy a regular volt meter and check the system's voltage by using the two terminals located in the front right side of your vehical.  One is + and the post is -   You NEVER know when the charging component will or has failed.

 

Send a letter to Ford to first fix the BMS and second to add a visual voltage meter  and Coolant Temperature gauge on the Left side of the panel.  They should also add parallel redundancy to the battery charging system with at least 3 systems and to redesign the system so that the car will not die once started if the battery dies.

 

Battery (12 v) failure MUST NEVER SHUT THE CAR DOWN WHEN BEING DRIVEN.

 

If you do not see the battery being charged while operating the vehicle contact your Ford Dealer ASAP and perhaps don't drive the car.

 

I am trying to warn all C-Max hybrid owners of this problem.  We had the most recent upgrade done on October 23 2014 when our Navigation System was repaired, one day before the battery died.  Ford tech's did not notice that the charging system was not working because no alarms were showing.

If you have a voltmeter plugged into your power point and the car in the on position you read 13.9-14.2v. I have seen as low as 11.4v before turning the car on and it still starts. I'm not sure if the car even needs a 12v batt. once it's started. It will be interesting to hear what FORD says. :) 

 

Paul

[plus 3 golfer]

One can monitor the battery voltage via the Engineering Test Mode (ETM) screen both before the car is "ready to drive" (before the DC/DC converter begins to charge the 12 V battery) and after the car is "ready to drive" (the DC/DC converter is activated to charge / maintain the 12 V battery).  I assume if the 12 V battery is "dead", one will not be able to enter the ETM screen.  I've seen 12.3 V before and generally 14+ V after the charging is activated. Search for ETM to find how to enter such.  Also, one can spend about $30 for and ELM327 module to plug into the OBDII port and an App for a smartphone and monitor the 12 V voltage while driving along with other interesting data.

 

AFAIK, no one has reported a failure of the 12 V battery system while driving the car.  That would imply a low impedance path to ground (bad battery or other low resistance path to ground) such that the DC/DC converter can't maintain sufficient 12 V system voltage  or a failure of the DC/DC converter and then subsequent 12 V voltage falling below a level sufficient to operate the control logic.  If your car has stalled while driving, you need to file a complaint with NHTSA (safercar.gov) as such may be a safety issue.  You can also look at all complaints filed with NHTSA.

 

You should never lose your brakes or steering.  Brakes and steering may suffer degradation when losing power, but one should still be able to brake and steer the car albeit a lot more difficult.  Again, if you suffered loss of brakes or steering while driving,  you need to file a complaint with NHTSA.   

[ptjones]

Also you still have the hand brake if you need to stop. :)

 

Paul

[stevedebi]

..

 

You should never lose your brakes or steering.  Brakes and steering may suffer degradation when losing power, but one should still be able to brake and steer the car albeit a lot more difficult.  Again, if you suffered loss of brakes or steering while driving,  you need to file a complaint with NHTSA.   

I had an intermittent problem with the electrical steering on my Escape Hybrid (there was a later recall). It caused the electric systems to go out, especiall the steering, and I can tell you that I was unable to effectively turn the car without the electric assist. I'd hate to have the electric steering go out on my C-Max Energi! Brakes, yes, the emergency brake will work.

[ptjones]

I had an intermittent problem with the electrical steering on my Escape Hybrid (there was a later recall). It caused the electric systems to go out, especially the steering, and I can tell you that I was unable to effectively turn the car without the electric assist. I'd hate to have the electric steering go out on my C-Max Energi! Brakes, yes, the emergency brake will work.

It is just another good reason to add another battery like I have in my thread "Possible Solution for Dead Battery Problem" if you are having dead battery problems. IMO :)

 

Paul

[Bill-N]

...  and Coolant Temperature gauge on the Left side of the panel....

 

FYI, coolant temperature can be added to MyView.  See your owners manual.

[stevedebi]

FYI, coolant temperature can be added to MyView.  See your owners manual.

Huh, I could have sworn I posted that information, but I don't see it here. I recently changed MyView to have that display. Everything else there is duplicated somewhere else, so I thought I might as well have it. Mine has RPM on the left and Temp on the right.

[ptjones]

Ordered digital voltmeter from ebay for $4.50 free shipping, should have beginning of next week.

• 
• 
• 
• 

 

 

  LCD Digital LED Car Battery Voltage Meter Voltmeter :)

 

Paul

Edited October 28, 2014 by ptjones

[plus 3 golfer]

I had an intermittent problem with the electrical steering on my Escape Hybrid (there was a later recall). It caused the electric systems to go out, especiall the steering, and I can tell you that I was unable to effectively turn the car without the electric assist. I'd hate to have the electric steering go out on my C-Max Energi! Brakes, yes, the emergency brake will work.

Exactly why there was a recall and why one should report such incident to NHTSA.  In fact, NHTSA recently opened an investigation on certain Ford products.  It wouldn't surprise me if more vehicles are added.  This is why anyone that has lost steering / brakes needs to file a complaint.

 

Date Investigation Opened: OCT 02, 2014

Date Investigation Closed: Open

NHTSA Action Number: PE14030

Component(s): STEERING 

All Products Associated with this Investigation 

 

Details  2 Associated Documents 

 

Manufacturer: Ford Motor Company

 

SUMMARY:The Office of Defects Investigation (ODI) has identified 508 complaints alleging loss of power steering assist and increased steering effort in model year (MY) 2010 to 2012 Ford Fusion, Mercury Milan and Lincoln MKZ vehicles equipped with rack mounted Electric Power Assisted Steering (EPAS). Four of these complaints allege that the steering assist failure resulted in increased steering efforts that contributed to a loss of control and crash. In addition, ODI has identified related information in Early Warning Reporting field report data submitted by Ford. Many of the complaints indicated observing a power steering warning message as the failure occurred. In some cases, the condition was corrected by turning the vehicle off and restarting. However, many reports indicate the condition returned again after restart. A Preliminary Evaluation has been opened to assess the scope, frequency and safety consequences of the alleged defect.

Edited October 28, 2014 by Plus 3 Golfer

[kaptnk228]

One can monitor the battery voltage via the Engineering Test Mode (ETM) screen both before the car is "ready to drive" (before the DC/DC converter begins to charge the 12 V battery) and after the car is "ready to drive" (the DC/DC converter is activated to charge / maintain the 12 V battery).  I assume if the 12 V battery is "dead", one will not be able to enter the ETM screen.  I've seen 12.3 V before and generally 14+ V after the charging is activated. Search for ETM to find how to enter such.  Also, one can spend about $30 for and ELM327 module to plug into the OBDII port and an App for a smartphone and monitor the 12 V voltage while driving along with other interesting data.

 

AFAIK, no one has reported a failure of the 12 V battery system while driving the car.  That would imply a low impedance path to ground (bad battery or other low resistance path to ground) such that the DC/DC converter can't maintain sufficient 12 V system voltage  or a failure of the DC/DC converter and then subsequent 12 V voltage falling below a level sufficient to operate the control logic.  If your car has stalled while driving, you need to file a complaint with NHTSA (safercar.gov) as such may be a safety issue.  You can also look at all complaints filed with NHTSA.

 

You should never lose your brakes or steering.  Brakes and steering may suffer degradation when losing power, but one should still be able to brake and steer the car albeit a lot more difficult.  Again, if you suffered loss of brakes or steering while driving,  you need to file a complaint with NHTSA.   

THANKS for your input.  Our car has been in the dealer's shop for over 1 week and we are driving a rental Fusion.  When we get it back I will look into the ETM.  Ours did die while we were driving.  Luckily we had stopped and were just going though the light as the car died.  It was very difficult to steer and when I was on the shoulder I had a heck of a time stopping the car from rolling.  i had to force the dealer to explain to me why or what had caused the battery failure.  It took over 1 day for them to tell me that the module for the charging system had failed.  We had no engine light or indication of this.  My wife would have had a terrible time driving the car under these conditions as would most people.  I have written Ford and will write to the NHTSA tomorrow.  If we had a battery failure light or the equivalent of the alternator light, I would have checked the voltage across the terminals in the front.  I will continue to check the running and stopped voltages until my meter arrives from China.  I had a spare battery in the back with cables but did not know how to access the battery compartment at that time.  I do now.  The charging system must have redundancy to prevent this from occurring.  It is very similar to what happened with the GM ignition switch failure.  GM were fined $51 million.

 

We have been driving a 2.5l Fusion which I love.  We have driven over 1000 miles on the Fusion and under 100 miles on our C-Max.  The fusion gets over 42 mpg at 65 mph, 37 at 74 mph.

 

Your help is most appreciated.  Thanks.  I have been reading the manual for weeks to learn what I can about this car.

[kaptnk228]

You should always be able to unlock the car with the key although I haven't tried it since I've never had a dead battery.

 

By the way, 31 deaths associated (100's injured) with the GM ignition switch which basically turned the car off.  

 

The battery failure and component turned the car off.  

 

If the highway was busier and I was going at 60 mph I don't want to think about what could have happened.  I didn't use the parking brake but will immediately if something like that happens again.  I prefer to check the battery voltage every day until this problem is properly fixed by Ford.  Remember with no power steering you naturally put two hands on the wheel making it much more difficult to use the parking brake.

 

Stop driving the car if you start seeing your 12 V battery levels below 12.5 volts or piggy back another battery  with jumper cables and drive to the dealer.  Keeping the 12 V battery fully charged with a small charger just might be very very good ideal.  The way to check your battery is first by voltage and second by the green/red light on top of the battery.  Unfortunately you have to remove the panel to see this light which is a big pain.

 

I will add the coolant temp to my view.  I had problems trying to change my view because I need to have both keys in hand to do that.

 

There may be other causes to why the battery dies.  That is why I asked Ford to tell me what happened.  No matter what, it will not run with a dead battery so monitor it closely.  Write Ford about this concern.  One poster blamed coolant leaking onto the unprotected wires had caused a drain.

 

Using the hand brake is a great thing to remember but you most likely will need to have both hands on the wheel as you lose power steering, brakes, air bags and hopefully not your life.

 

Remember to GM their customers lives were worth $2.40  

 

We live in Canada less than 50 miles from where the car was built.  Ford USA must be made aware of this problem.  To them, Canada is some 3rd world country.  Please let your voices be known.

 

If we know that the battery level is low we can stop driving the car, charge or replace the battery and find out the cause of the problem.  Not knowing could result in your death like it did

to 31+GM owners (100's injured) who had their ignition switch move to accessory position.  Don't you just love how GM tried to cover it up by fixing the part and keeping the same part number on never models.

Edited November 4, 2014 by kaptnk228

[stevedebi]

 

By the way, 12-18 deaths associated with the GM ignition switch which basically turned the car off.  The battery failure and component turned the car off.  If the highway was busier and I was going at 60 mph I don't want to think about what could have happened.  I didn't use the parking brake but will immediately if something like that happens again.  I prefer to check the battery voltage every day until this problem is properly fixed by Ford.

 

The GM ignition switch deaths were because it also disabled the air bags. I don't know if the reported errors would also cause that. Possibly.

[stevedebi]

One can monitor the battery voltage via the Engineering Test Mode (ETM) screen both before the car is "ready to drive" (before the DC/DC converter begins to charge the 12 V battery) and after the car is "ready to drive" (the DC/DC converter is activated to charge / maintain the 12 V battery).  I assume if the 12 V battery is "dead", one will not be able to enter the ETM screen.  I've seen 12.3 V before and generally 14+ V after the charging is activated. Search for ETM to find how to enter such.  Also, one can spend about $30 for and ELM327 module to plug into the OBDII port and an App for a smartphone and monitor the 12 V voltage while driving along with other interesting data.

 

AFAIK, no one has reported a failure of the 12 V battery system while driving the car.  That would imply a low impedance path to ground (bad battery or other low resistance path to ground) such that the DC/DC converter can't maintain sufficient 12 V system voltage  or a failure of the DC/DC converter and then subsequent 12 V voltage falling below a level sufficient to operate the control logic.  If your car has stalled while driving, you need to file a complaint with NHTSA (safercar.gov) as such may be a safety issue.  You can also look at all complaints filed with NHTSA.

 

You should never lose your brakes or steering.  Brakes and steering may suffer degradation when losing power, but one should still be able to brake and steer the car albeit a lot more difficult.  Again, if you suffered loss of brakes or steering while driving,  you need to file a complaint with NHTSA.   

This brings up an interesting question. Some models of the conventional C-Max hybrid do not have the push button start. Does the ETM work on those models?

 

It is not a factor for the Energi, which I believe always comes with the push button starting.

[kostby]

This brings up an interesting question. Some models of the conventional C-Max hybrid do not have the push button start. Does the ETM work on those models?

 

Yes. Engineering Test Mode (ETM) is activated on the SE by holding down the left-steering-wheel OK button when turning the car from off to ignition-on and holding OK until the ETM display begins (a yellow ET is displayed in the upper left corner) of the left-hand screen).

 

It is not necessary to actually turn the key another notch to "start" the vehicle. The only way to turn off ET is to turn the key off. Once activated, ET will continue on the left-hand display once the vehicle is started, covering the usual left-hand trip odometers, MyView, and Power screens.

[stevedebi]

Yes. Engineering Test Mode (ETM) is activated on the SE by holding down the left-steering-wheel OK button when turning the car from off to ignition-on and holding OK until the ETM display begins (a yellow ET is displayed in the upper left corner) of the left-hand screen).

IMG_5192med.jpg

 

It is not necessary to actually turn the key another notch to "start" the vehicle. The only way to turn off ET is to turn the key off. Once activated, ET will continue on the left-hand display once the vehicle is started, covering the usual left-hand trip odometers, MyView, and Power screens.

I noticed the first couple of times I tried it that if I accidentally hit the OK button again, it dropped out of ETM. But that may only work when the initial start screen on the left side is active.

[ptjones]

I got plug in battery meter today and tested it out in power point. I had been driving around the city and checked my mail box and there it was so batteries charged up and reading 14.7vdc, seems kinda high so I tried out my hand held Voltmeter and was reading the same. Then I checked my 12v battery and it was reading the same, no voltage drop. Turned car off and was reading 12.7vdc, later I will check it when I open the door. :)

 

Checked voltage several hours later and it had dropped to 12.1vdc.

 

Paul

Edited November 1, 2014 by ptjones

[kaptnk228]

Check the terminal voltage under the hood and compare.  It should never be that low.  Your charging system is working typically 13.5-14.5 V

 

At 12.1 V I would be attaching my battery charger to check out the battery.  Check the battery to see if the green or red light is on.  Red is dead.  You most likely will have to remove the back cover by pushing in the 3 buttons and lifting it up near the latch.  I have not done that yet but the tech showed me how to do it.  I would be checking battery fluid level if possible.  An over charged battery will boil off electrolytes (or just water) exposing the plates in the battery.  Only add deminerlized water to a battery.

[ptjones]

Check the terminal voltage under the hood and compare.  It should never be that low.  Your charging system is working typically 13.5-14.5 V

 

At 12.1 V I would be attaching my battery charger to check out the battery.  Check the battery to see if the green or red light is on.  Red is dead.  You most likely will have to remove the back cover by pushing in the 3 buttons and lifting it up near the latch.  I have not done that yet but the tech showed me how to do it.  I would be checking battery fluid level if possible.  An over charged battery will boil off electrolytes (or just water) exposing the plates in the battery.  Only add deminerlized water to a battery.

I think it has been this way since New. I posted these  voltages when the CMAX was only  few month after getting the car. It would be nice if everyone would check their voltages before starting the car and after to get a range to look at. :)  I would think the car's computers would operate down to 10v anyway. IMO

 

Paul

[plus 3 golfer]

I think it has been this way since New. I posted these  voltages when the CMAX was only  few month after getting the car. It would be nice if everyone would check their voltages before starting the car and after to get a range to look at. :)  I would think the car's computers would operate down to 10v anyway. IMO

 

Paul

Do you get the same voltages if you check in ETM?

 

I've spot checked mine on rare occasion in ETM and the lowest IIRC that I've seen was 12.3 V.  I would suggest that everyone use ETM to monitor voltages for consistency prior to start-up and then after start-up (DC/DC converter charging).  Perhaps we should start a new thread on this.  Here's my monitoring for the last two days.   

 

[ptjones]

Just checked voltage in ETM and it reads .5volts less than my plugin voltmeter which I verified with hand held voltmeter.  So in ACC.position 12.5v/13v and on position 14.2v/14.7v also just opening the car door I had 12v on voltmeter so I guess 11.5v on ETM. Not sure what to make of it, but it has been working since day one. :)

 

Paul

[plus 3 golfer]

I just checked and same here, ETM reads about 0.5 V lower than my voltmeter at the under hood battery posts -  12.5 V / 12.95 V and 14.0 V / 14.48 V.  

 

With the car "off"  and hood and hatch open, I get the same reading at the under hood posts and at the battery - 11.8 V.   A "good" 12 V lead acid battery should never read 11.8 V across the battery terminals. However, there is a metering circuit between the ground post of the battery and the chassis ground.  So, my guess is that the voltage drop across the metering circuit in the battery to chassis ground circuit is at least 1/2 V or likely more when there is virtually no load on the battery with the car off.  The DC/DC converter is not connected to the 12 V system.

 

Now apparently with the car in ACC. / On Mode or start mode, the DC/DC converter is switched on and connected to the 12 V system.  My guess is that in the ACC. /On mode (at least initially) the converter is supplying a sustaining charge maintaining 12 V system voltage.  But in the start mode, the DC/DC is now acting as an alternator like on an ICE vehicle charging the 12 V battery and hence the higher voltage reading.  Now, for why the difference in voltage readings between ETM and a voltmeter.  What makes sense is that the ETM is measuring the battery voltage across the terminals of the battery as there is a voltage measurement circuit to the Battery Control Module.  The voltmeter however is not measuring battery voltage but the voltage across the DC/DC converter which apparently needs to be about 1/2 V higher than the battery terminal voltage due to the voltage drop across the metering circuit of about 1/2 V for proper operation.

 

So, it appears that 1) using ETM to monitor battery voltage won't work as the DC/DC converter will always be connected and 2) measuring battery voltage with a voltmeter with the car off does not indicate the battery terminal voltage.  This is why owners have reported measuring low battery voltages (indicating virtually no charge in the battery) yet the car start.  We can assume a 1/2 V difference with the car off but we don't know whether the voltage drop across the metering circuit is constant at battery voltage changes (especially as the battery is discharged).  My guess is that it is not a constant.

 

This makes sense to me.  Any thoughts?  One way to test this is to remove the cargo area cover and actually measure voltages across the battery terminals with the car off against ETM and posts under the hood.

[ptjones]

I took cover off battery compartment and there is no difference any voltages measured anywhere with a voltmeter. I measured across the batt. terminals, batt. ground to car and power point. With lights shutting down I got a high of 12.2v and with lights on and door open 11.8v. Obviously there is no problem, but it isn't what you expect. I wonder about the size of the 12v battery? :) 

 

Paul 

[plus 3 golfer]

After thinking about it, 1/2 V drop is way too high for a metering circuit on a 12 V system.  

 

I checked ETM voltage readings with DashCommand and the readings are identical for On and Start modes. The interesting thing is that when I shut the car off, DashCommand is still scanning and the voltage reading decreases gradually to 11.8 - 12.0 V (in about 5+ or so seconds of scanning).  Thus, in the off mode, the voltage readings in DashCommand and via a voltmeter are the same.

 

Yes, I wonder if increasing the battery capacity would affect the voltage readings.  Remember the Service Manual says to replace the battery with one of the same size as it will affect "something" as the Battery Control Module monitors the 12 V battery. 

 

The Battery Monitoring Sensor continuously monitors the condition and the state of charge of the 12V battery and provides the BCM with this information. The BatteryMonitoring Sensor

also estimates losses in the battery capacity over time. The Battery Monitoring Sensor should only be reset when the battery is replaced. It is urgently recommended that the

replacement battery has the exact same specification as the original battery. If it does not, the accuracy of the Battery Monitoring Sensor outputs will be compromised.

 

The Battery Monitoring Sensor is clamped directly to the negative terminal of the battery and grounds to the vehicle at the chassis ground connection point through the negative battery

cable and eyelet. It is part of the negative battery cable and cannot be serviced separately.

 

External customer loads must only be connected to the vehicle at the customer battery connection point. If an external customer load is connected at the negative battery post, the

Battery Monitoring Sensor accuracy cannot be guaranteed. It is recommended that the Battery Monitoring Sensor pole clamp is not removed unless a batteryreplacement is required.

Should the battery need to be isolated, this should be done by disconnecting the ground eyelet at the chassis ground.

 

Body Control Module (BCM)

The BCM monitors the Battery Monitoring Sensor and provides the PCM with battery state of charge information. 

 

 

[kaptnk228]

Our battery problem is solved for now:  

 

Cause:

 

1. Failed dc/dc charger that floats 14.3-5 Volts on battery when car is started.

2. The culprit for the battery drain was a high amp fuse!!  It caused the charging voltage to drop to 13.5 V (no alarm but there should be one) and to drain battery when car is off

3.  No battery low or charging system alarms to tell you.

 

As soon as it failed it told the dealer not to just replace the battery but figure out what caused it to drain.  The fuse was the difficult one.  An infrared camera might have picked up the hot element.  I told them to follow the current to the component that was draining the battery.  It took 2 weeks but we are working again and enjoying our C-Max.

 

Ford still have to fix the NO ALARM problem.  Until that is fixed we will run a volt meter in the 12 V socket to monitor the battery/charging system.  This should be part of the standard instrumentation ofthe car.

 

You may have another cause but I suspect this fuse problem is causing a lot of batteries to fail.

 

retired P.Eng.