Possible 12volt Dead Battery Solution

[ptjones]

Well I did some research on the 12 volt Battery and came up with some interesting INFO. Someone may have done this already. The 12v battery in car Part# BXT-67R-390CCA yet in the OM the replacement batteries listed are Part# BXT-96R-500CCA and BXT-96R-590CCA. The dimensions of BXT-67R are 8"L X 6"W X 7" H. The only place I could find a battery for CMAX other than FORD was Batteries+Bulbs Part# SLI 96R for $107  9.56"L X  6.87"W X  6.87" H. This would be a great solution if it fits, going from 390CCA to 600CCA with 60% more power may eliminate dead 12v battery problem. IMO :) 

 

Paul 

[mtb9153]

Well I did some research on the 12 volt Battery and came up with some interesting INFO. Someone may have done this already. The 12v battery in car Part# BXT-67R-390CCA yet in the OM the replacement batteries listed are Part# BXT-96R-500CCA and BXT-96R-590CCA. The dimensions of BXT-67R are 8"L X 6"W X 7" H. The only place I could find a battery for CMAX other than FORD was Batteries+Bulbs Part# SLI 96R for $107  9.56"L X  6.87"W X  6.87" H. This would be a great solution if it fits, going from 390CCA to 600CCA with 60% more power may eliminate dead 12v battery problem. IMO :)

 

Paul 

Interesting research Paul, I'd definitely like to know whether this would work as a replacement to the factory battery and more CCA to go along with it.  Couldn't hurt folks in really cold venues during the winter months.

[Kelleytoons]

I wonder if the batteries listed now in the OM are changed as a result of battery issues.  IOW, if I understand you correctly, now Ford only offers bigger batteries than our original equipment has.

[plus 3 golfer]

This topic has been discussed before.  Here's a link to the Motorcraft battery specs.  The key is not CCA but Ah capacity / reserve capacity (RC)..  

 

Changes in  CCA generally track with changes in Ah capacity but it does depend on the battery. Also without knowing the discharge current, it is not possible to estimate the benefit gained by a larger battery.  Discharge current affects battery capacity. As an example (not based on actual data), if the discharge current is 5 Amps, the Ah rating might be 100 Ah or in essence the battery can supply 5 A for 20 hours.  But if the discharge current is say 10 A, the Ah rating might be 60 Ah for the same battery and the battery can supply 10 A for 6 hours.   So even if the battery capacity were larger, the benefit gained by such larger battery may still not cover the drain from whatever is causing the problem.  So in the example, doubling the battery capacity might get one 12 hours at a 10 A drain which still may not be sufficient to mitigate the dead battery. I doubt we can find a battery that has twice the Ah capacity as the OE to fit in the C-Max battery space.

 

Bottom line, a larger capacity battery is better than a smaller capacity battery but there's no guarantee that a larger battery will mitigate having dead batteries.  

 

As far as fitment, there are attachments on the cable that also need "to fit" in the battery space.  I've looked before and there's not a lot of extra room in the battery compartment.  The Motorcraft spec shows the 96R battery to be 0.70 inches longer than the 67 R.  As I've said before someone needs to "test fit" the 96R battery into the C-Max.  Also, I don't know what effect a larger battery might have on the C-Max 12V battery SOC model.  Here's a link provided in another thread about battery size (from this the 96R might fit).

 

 

[ptjones]

I went to FORD and Batteries+ and took my battery out and tried to put other possible batteries in the Batt. tray, but they wouldn't fit. Darn! :rant2: It would be possible to make a bigger tray that a bigger battery would fit. Otherwise BXT 67R is the only battery that will fit. OM gives the wrong Battery numbers. The person a Batteries+ said they would look into seeing if the company could come out with a higher AHr Batt. for CMAX. ;)

 

Paul

[ptjones]

Well I went back to Batteries+ , I had an idea that we could a smaller sealed battery above the CMAX battery in storage compartment and connect it in Parallel to increase the total AHrs enough to solve the dead battery problem. I found Part# WKA12-26NB around $80 that fit real nice. :)

[mtb9153]

Paul, is Batteries+ an automotive chain store or are they only located near you?  Wondered.  We have a chain of stores here with the same name but I don't think they sell automotive batteries.  Curious.

[HPRifleman]

Multiple or larger batteries are not a solution to the problem of the 12v battery being discharged in some vehicles. The solution is to find and fix the unintentional draw on the batteries in those vehicles.

[ptjones]

Paul, is Batteries+ an automotive chain store or are they only located near you?  Wondered.  We have a chain of stores here with the same name but I don't think they sell automotive batteries.  Curious.

They are a national chain and you can get any kind of battery there.

 

Multiple or larger batteries are not a solution to the problem of the 12v battery being discharged in some vehicles. The solution is to find and fix the unintentional draw on the batteries in those vehicles.

Until FORD can find all the problems causing dead 12v batteries , this could be a interim fix. I would do this if I was having continuing 12v battery problems ( Batteries+ could actually do this for you)  plus jumper battery, that way I would have all the bases covered. IMO :)

 

Paul

[homestead]

Multiple or larger batteries are not a solution to the problem of the 12v battery being discharged in some vehicles. The solution is to find and fix the unintentional draw on the batteries in those vehicles.

+1

[dmk2000]

They are a national chain and you can get any kind of battery there.

 

Until FORD can find all the problems causing dead 12v batteries , this could be a interim fix. I would do this if I was having continuing 12v battery problems ( Batteries+ could actually do this for you)  plus jumper battery, that way I would have all the bases covered. IMO :)

 

Paul

In my case, mid size  jumper battery was not able to revive CMAX. Prolonged charging of 12 V battery at 8A (40 min) did a trick. After this incident, I view jumper battery not as reliable solution as I was hopping it to be. 

Edited September 30, 2014 by dmk2000

[obob]

In my case, mid size  jumper battery was not able to revive CMAX. Prolonged charging of 12 V battery at 8A (40 min) did a trick. After this incident, I view jumper battery not as reliable solution as I was hopping it to be. 

 

That worrisome.  What mid size battery did you use ?

 

I have one of these

 

http://www.amazon.com/PowerAll-PBJS12000R-Rosso-Portable-Starter/dp/B00D42AFS8/ref=sr_1_3?ie=UTF8&qid=1410659456&sr=8-3&keywords=jump+starter

 

I was assuming I was protected.

[dmk2000]

I had this one:

 

http://www.amazon.com/Schumacher-XP400-Instant-Portable-Source/dp/B004EIDD2Q/ref=pd_sbs_auto_4?ie=UTF8&refRID=1VW8M5ZK2V9TCATPD4HV

 

it is 400 A.

[ptjones]

I had this one:

 

http://www.amazon.com/Schumacher-XP400-Instant-Portable-Source/dp/B004EIDD2Q/ref=pd_sbs_auto_4?ie=UTF8&refRID=1VW8M5ZK2V9TCATPD4HV

 

it is 400 A.

I was wondering if the jumper battery was fully charged.  BTW the only time I had a dead battery was caused by leaving the accesory position on, so I used 6A charger for a few minutes. Then started the car with charger connected for as it took to get out of the car and disconnect it. Also your jumper would have started the car if you would have disconnected one of the terminals of the car battery, started the car with jumper battery and then reattached the battery cable. :) 

 

Paul 

[obob]

I had this one:

 

http://www.amazon.com/Schumacher-XP400-Instant-Portable-Source/dp/B004EIDD2Q/ref=pd_sbs_auto_4?ie=UTF8&refRID=1VW8M5ZK2V9TCATPD4HV

 

it is 400 A.

 

The one I have is also rated at 400 A.

 

 

I was wondering if the jumper battery was fully charged.  BTW the only time I had a dead battery was caused by leaving the accesory position on, so I used 6A charger for a few minutes. Then started the car with charger connected for as it took to get out of the car and disconnect it. Also your jumper would have started the car if you would have disconnected one of the terminals of the car battery, started the car with jumper battery and then reattached the battery cable. :)

 

Paul 

 

So if I read into this right, taking the battery out of the system takes away something that is using up the jump current. Nice.

[ptjones]

The one I have is also rated at 400 A.

 

 

 

So if I read into this right, taking the battery out of the system takes away something that is using up the jump current. Nice.

What is happening is you end up charging dead battery with jumper battery and the drop in voltage is great enough to drop below what the minimum voltage for the computers need to boot up. Taking  the dead battery out of the circuit allows voltage to stay high enough to start the car and then you can reconnect dead battery and allow it to recharge. :)

 

Paul

[dmk2000]

What is happening is you end up charging dead battery with jumper battery and the drop in voltage is great enough to drop below what the minimum voltage for the computers need to boot up. Taking  the dead battery out of the circuit allows voltage to stay high enough to start the car and then you can reconnect dead battery and allow it to recharge. :)

 

Paul

+1.

The problem is it is a pain in the butt to disconnect + terminal from the battery. I hope there is a easy accessible fuse somewhere to achieve this.

[plus 3 golfer]

There is a Battery Fuse Assembly near the 12 V battery that contains a 150 A fuse but I can't tell exactly where the assembly is without accessing the battery and whether the fuse is a serviceable component of the assembly. IIRC from looking at the 12 V battery prior, there is an assembly attached to the battery cable which I believe it was on the +terminal. So, it may be just as easy to remove the + cable from the battery.  

 

Also, from the wiring diagrams, I can't readily determine whether the positive post under the hood is connected before or after the fuse assembly.  But the positive post is connected to a bus with multiple positive feeds which leads me to believe the positive post is after the 150 A fuse.  So, if the 150 A fuse can be easily located and pulled, one could pull the fuse, clamp a jump start on the posts under the hood and perhaps be able to start the car with the 12 V battery not connected.  

 

The problem though with either disconnecting the positive lead or pulling the fuse may be that if the car starts, the DC/DC converter is operating and there will likely be a significant arc and perhaps power surge from the converter as a dead battery will have a high draw.  There is a 175 A fuse in the battery box under the hood to protect the DC/DC converter from excessive loads / shorts and this could blow.  Also, there is a 12 V battery ground current flow sensor / algorithm that initially sees zero current flowing through the dead 12 V battery.  So, we don't know how this might affect the issue when putting the fuse back in / connecting the positive cable with the car now on.

[dmk2000]

There is a Battery Fuse Assembly near the 12 V battery that contains a 150 A fuse but I can't tell exactly where the assembly is without accessing the battery and whether the fuse is a serviceable component of the assembly. IIRC from looking at the 12 V battery prior, there is an assembly attached to the battery cable which I believe it was on the +terminal. So, it may be just as easy to remove the + cable from the battery.  

 

Also, from the wiring diagrams, I can't readily determine whether the positive post under the hood is connected before or after the fuse assembly.  But the positive post is connected to a bus with multiple positive feeds which leads me to believe the positive post is after the 150 A fuse.  So, if the 150 A fuse can be easily located and pulled, one could pull the fuse, clamp a jump start on the posts under the hood and perhaps be able to start the car with the 12 V battery not connected.  

 

The problem though with either disconnecting the positive lead or pulling the fuse may be that if the car starts, the DC/DC converter is operating and there will likely be a significant arc and perhaps power surge from the converter as a dead battery will have a high draw.  There is a 175 A fuse in the battery box under the hood to protect the DC/DC converter from excessive loads / shorts and this could blow.  Also, there is a 12 V battery ground current flow sensor / algorithm that initially sees zero current flowing through the dead 12 V battery.  So, we don't know how this might affect the issue when putting the fuse back in / connecting the positive cable with the car now on.

Very good point. 

[ptjones]

+1.

The problem is it is a pain in the butt to disconnect + terminal from the battery. I hope there is a easy accessible fuse somewhere to achieve this.

Disconnecting Positive battery cable takes about a minute to do. Just lift up the rear compartment storage cover and then lift up the rubber mat over battery cover. Lift up battery cover and there is the positive battery cable, remove with a 10mm socket wrench, easy. You can see the positive battery cable in Post# 6

 

I think the best method for reinstalling battery cable is to leave jumper connected under the hood until after to lessen the draw on Inverter. IMO :)

 

Paul 

[plus 3 golfer]

I forgot about Paul's pics.  I believe the fuse assembly box with the 150 A fuse is the red colored box that is seen on the side of the battery in the pic.  Positive from the battery terminal goes into the red box and there are 2  wires attached to an exit bus from red box. So, it appears that there is no easy access to the 150 A fuse in the box.  Just need to carry a 10 mm socket wrench with the jump start.  :)

 

Here's a snippet of the battery wiring diagram for reference.  Note that when the + connector on the battery is disconnected, the battery monitoring circuit is still in tact although the flow would be zero through the battery.  

 

IMO, those with jump starts might want to test their jump start before actually having a dead battery.  Also, It may be easier to remove the negative ground cable from it's attachment point at the body instead of the + battery connector. Proceed at your own risk with any testing. :)

 

 

 

[obob]

There is a Battery Fuse Assembly near the 12 V battery that contains a 150 A fuse but I can't tell exactly where the assembly is without accessing the battery and whether the fuse is a serviceable component of the assembly. IIRC from looking at the 12 V battery prior, there is an assembly attached to the battery cable which I believe it was on the +terminal. So, it may be just as easy to remove the + cable from the battery.  

 

Also, from the wiring diagrams, I can't readily determine whether the positive post under the hood is connected before or after the fuse assembly.  But the positive post is connected to a bus with multiple positive feeds which leads me to believe the positive post is after the 150 A fuse.  So, if the 150 A fuse can be easily located and pulled, one could pull the fuse, clamp a jump start on the posts under the hood and perhaps be able to start the car with the 12 V battery not connected.  

 

The problem though with either disconnecting the positive lead or pulling the fuse may be that if the car starts, the DC/DC converter is operating and there will likely be a significant arc and perhaps power surge from the converter as a dead battery will have a high draw.  There is a 175 A fuse in the battery box under the hood to protect the DC/DC converter from excessive loads / shorts and this could blow.  Also, there is a 12 V battery ground current flow sensor / algorithm that initially sees zero current flowing through the dead 12 V battery.  So, we don't know how this might affect the issue when putting the fuse back in / connecting the positive cable with the car now on.

 

So does this mean that I could mess something up if I were to do this ?

 

Thanks.

[plus 3 golfer]

So does this mean that I could mess something up if I were to do this ?

 

Thanks.

Probably not. But, one function of a battery is to "smooth" voltage surges / transients so as not to damage electronics. Hopefully, the jump start battery will do such while connected. Leaving it connected as Paul suggests when connecting the main battery should mitigate potential issues.

 

The fact that the jump start didn't work for one poster with the 12V battery still connected makes me wonder why. If it was because the 12V battery was virtually discharged and had too high of a draw on the system such that the system couldn't maintain the threshold voltage to start the car with the jump start battery, I'd be concerned with in essence short circuiting the positive bus to ground through a discharged battery (likely very large draw from the jump start and converter).  It may be okay but I don't know what that draw might be.

 

When normally charging a dead battery, the battery charger limits the charging current and a good charger controls how the battery is charged.  This certainly would not be the case for the jump start battery supplying charging current to the 12V battery.  I would think that the DC/DC converter limits / controls charging current.  But this algorithm would likely be based on the 12 V battery sensing SOC algorithm which given the setup with a jump start connected and the 12 V battery disconnected likely yields erroneous results.     

Edited October 1, 2014 by Plus 3 Golfer

[ptjones]

We need to have someone with a dead 12v battery that can't be jumped to try this procedure out. I still think having the additional 12v could solve the dead battery problem for most CMAX's. IMO It would be nice If someone with continuing 12v battery problems would try this fix. I would do it, but it wouldn't prove anything because I'm not having 12v Battery problems. :) 

 

Paul 

[kaptnk228]

We recently bought a 2013 Ford C-Max.  The day after the navigation system was fixed, I found our loved C-Max in the driveway dead.  I tried starting it with our boat battery but it would not continue to run.

 

I charged the battery until my charger showed 75% and tried to drive it to the dealer 15 mins away.  IT DIED ABOUT 8-10 MINS LATER.  60 seconds before it died on the road, the battery light came on.  THE BATTERY WAS COMPLETELY DEAD.

 

As an Engineer this is what I believe happened.

 

A 12 Volt battery is not 12 Volts but rather it is 12.8 Volts when fully charged and the charging system normally floats 13.5 Volts on the battery.  There is no alternator and the system simply uses a transformer type of system to lower the Li Ion battery voltage to the desired DC voltage.

 

PERHAPS THE PROGRAMMER PROGRAMMED THE LOW BATTERY LIGHT TO COME ON AT 12 VOLTS LIKE IT DID IN OUR CASE.  IT SHOULD COME ON AT 12.8 VOLTS TO WARN  OF A FAILED CHARGING COMPONENT.  

 

SMALL PROBLEMS IN AIR PLANES HAVE COST 10,000'S OF PEOPLE THEIR LIVES.

 

WE GOT NO WARNING OF THE  FAILURE OF THE CHARGING SYSTEM OR BATTERY UNTIL JUST BEFORE THE CAR DIED.  IN THE PAST WE WOULD GET AN ALTERNATOR LIGHT TO COME ON as soon as the charging system failed.  I know that there is a battery light NOW simply fix the problem with a simple program update ASAP.

 

WHEN ONE DESIGN'S NEW CONCEPTS SOME OF THE OLD IDEAS MUST BE RE-EVALUATED.  THE CHARGER COMPONENT IMHO MUST BE RE-DESIGNED TO BE MULTI-COMPONENT.  THAT IS TO SAY FOR EXAMPLE, HAVE 3 OR 4 PARALLEL SYSTEMS WITH INDIVIDUAL WARNING LIGHTS.  WHEN ONE SYSTEM FAILS, WE WOULD BE NOTIFIED THAT WE MUST MONITOR THE OTHER TWO.  WHEN 2 FAIL IT IS TIME TO REPLACE THAT MODULE.

 

IN THE C-MAX ALL OF YOUR STEERING, BREAKING FLASHERS QUIT WHEN YOU LOSE THE 12 VOLT SYSTEM.  THIS CAN NOT BE ALLOWED TO HAPPEN.

 

Summary: 26 October 2014

 

1. Immediately fix the warning system of a fault with the 12 volt battery system.

2. Re-design the step down charger to be fault tolerant, ie build at least 3 if not 4 step down devices in parallel so if one or two fail, we will live and can go to dealer to get it replaced.  As it is taking over 5 days to get spare parts, this is a good idea.  Also design the system to last longer 

3.0 RE-DESIGN THE SYSTEM ONCE STARTED TO BE ABLE TO RUN WITHOUT THE 12 VOLT BATTERY UNTIL YOU TURN THE CAR OFF.  THIS WILL PREVENT THE MORE SERIOUS CONDITION OF A DEAD CAR AT SPEED LIKE WHAT OCCURRED TO US.

4.0 ALL OWNERS OF THE C-MAX MUST WRITE FORD AND PERHAPS SOME GOVERNMENT SAFETY BRANCH TO LOOK INTO THIS.

5.0 FORD SHOULD ADD ONE OF THEIR GREAT LOOKING PANELS ON THE LEFT SIDE TO MONITOR BATTERY VOLTAGE IE 13.5 VOLTS AND ALSO SHOW ENGINE COOLANT TEMPERATURE WHICH IS ALSO MISSING.

 

This is a relatively small problem with HUGE CONSEQUENCES.  IF THIS HAPPENS AT 70 MPH AND YOU DON'T HAVE ANY POWER BRAKES, OR STEERING OH MY GOD!!!!

 

Retired Professional Engineer 26 October 2014

 

WHAT TO DO UNTIL FORD FIXES THIS PROBLEM?

 

BUY A VOLTAGE METER AND A SMALL ADAPTER TO USE THE CIGARETTE LIGHTER POWER SUPPLY TO MONITOR THE SYSTEM.  YOU SHOULD THEN SEE THAT THE CHARGING SYSTEM IS WORKING.  A NORMAL CAR BATTERY FULLY CHARGED IS ABOUT 12.8+ VOLTS.  A DEAD 12 VOLT BATTERY OCCURS AT ABOUT 12 VOLTS LIKE IT DID IN OUR CASE.

 

The C-Max looks like a great car that just needs a few very important but small changes.

 

PROBLEM FOUND

 

1. DC/DC MODULE REPLACED

2. BATTERY REPLACED

3. VOLTAGE DROPPED TO 13.5 V BUT THEY REPLACED SOME LARGE AMP FUSE AND NO MORE PROBLEM.  Voltage when back to spec of 14.3 V+

4. No problem for the past month Dec 13 2014 today

5. Using voltmeter in 12 V socket to monitor charging system.  We get a strange 12.2 V when the car is turned off but it should be way higher.  I just ignore that for now as other thing may be on for a while.  No dead battery no problem.  15V will charge battery just fine  from the dc/dc module

 

Retired Mechanical Engineer who works on his car for the past 48 years.

Edited December 13, 2014 by kaptnk228