BXT-99R-390 Battery Discharge Plot

[murphy]

I removed the battery from my car and fully charged it.

I then put a 15 ohm 10 watt resistor across the battery and measured the voltage at one minute intervals for 1703 minutes (28 hours and 23 minutes) using a computer controlled voltmeter.  15 ohms across 12 volts is 0.8 ampere.  As the voltage drops the current also drops.

 

Note how quickly the voltage drops below 12 volts.

 

 

 

It's no wonder the car goes into battery preservation mode.

 

[BadRock]

Wow, that's pretty odd.

[larryh]

So 0.8 amperes is only a 12*0.8 = 10 watt load?  That's not much of a load.  But I would hope that it would usually draw a lot less than that when it is off.  What should the graph look like for a car battery?

Edited August 1, 2013 at 01:34 AM by larryh

[pluggedin]

It's no wonder the car goes into battery preservation mode.

So is there a cure or better, recommended, option at this point?

[Andre07]

Thank you, Murphy.

 

Great job on your experiment and the Graph.

 

This is exactly what we were looking for.

 

Next would be to try to find out at what Voltage on the 12 Volt Lead Acid Battery, the Low Voltage system stops working at.

 

Additionally I wonder what a 12 volt Lead Acid Load Tester, used to check the condition of a Battery would show when this battery is tested.  Most Garages have the proper Load Tester which can measure the Ampicity of a Battery when given a Heavy Load.

 

I really find it strange why Ford would even bother to use a Lead Acid Battery for the Control Voltage when the HVB could have a 12 Volt Tap off it to operate the 12 Volt System.  Since the Computer will start the ICE when the HVB has less been depleted overver 6 KWh as has been posted by a few Members here.

 

Really makes no sense to have a separate Battery for the 12 Volt System, but if there is a reason that I fail to understand why then did they not use a LiOn Battery that is rated at 12VDC instead of a Lead Acid Battery?

 

Carrying on with this; if a separate 12VDC Battry is required then why is it not charged by the HVB Pack when it drops below a certain Voltage, say 11.5 VDC or a Voltage safe enough to operate all it needs to instead of merely going Dead whren the HVB may be fully loaded.

 

Just makes no sense to me.

 

I have contacted my Energi Certified Ford Dealer Manger and advised them of these 12 Volt Battery short comings and that if they are not corrected I may delay purchasing an Energi that I am about to order, until these issues are corrected..

 

I also asked why there is nothing on the Displays or the MFT about the State of Charge of the 12 Volt Battery.

 

I will post what I get as a reply.

Edited August 1, 2013 at 03:05 AM by Andre07

[Andre07]

So 0.8 amperes is only a 12*0.8 = 10 watt load?  That's not much of a load.  But I would hope that it would usually draw a lot less than that when it is off.  What should the graph look like for a car battery?

Regular Car Battery Graph would be much different since most have rating over 650 Ah for Deep Cycle and over 750 Ah if used for Cracking.

 

Voltage indicates how much Electrical Potential is available on a Battery and usually the working Voltage for a 12 Volt System is from 10 Volts to 12 Volts but Voltage means nothing if it does not have enough Current Flow to pick up Relays and for that you need a Battery to be able to deliver enough Current, is why it is important to know what the Ampicity of a Battery is, indicated in Amp Hours. 

 

Case in Point we can take a 125 CC Motorcycle Battery that delivers 12Volts and enough Amperes to turn over the Motorcycle but would not eve pick up the Relay to start a car or enough to have the head Lights on for more than a few minutes before it dies.  I belive these tiny Batteries are rated at under 100 Ah, Amp Hours.

 

Looking at Murphy's Graph where he plots Voltage versus time we could very easily also plot Current vs Time.

 

For those not familiar with Ohm's Law

 

The Current is directly Proportional to the Voltage if the Resistor is constant and we neglet the change in resistance as it heats up.

 

Ohms Law states that E=IR  Voltage is equal to Current times Resitance

 

So to find the Current we take  I=E/R  .. Current equals Voltage divided by Resistance

 

Looking at the Garph when the Battery Measured 12.2V the current was  I = 12.2/15 = 0.81 amps

 

At 12.0 V ... I = 12.0/15 = 0.80 A

at 11.5 V  ...I = 11.5/15 = 0.74 A

at 11.0 V ... I = 11.0/15 = 0.73 A

at 10.5 V ... I = 10.5/15 = 0.70 A

at 10.0 V ... I = 10.0/15 = 0.67 A

 

Now if all the relays used by Ford can operate at 0.65 A or lower then they should pick up even at the reduced Voltage of 10.0V and 0.67 Amps which means they would be rated at W=IxE  or 10.0V * 0.67 = 6.7 Watts

 

But if any relay operates at 0.75 A or 750 mA or higher then the Battery needs to be at a Potential higher than 11.5V to Operate.

 

I would think that if the doors were open and Running and head Lights were on, it would not take too long to drain this Battery cause the Battey would then need to supply over 10 Amps and at a state of Charge of 12.0 VDC it would need to supply W=I*E= 10 * 12 = 120 Watts.  Leave these on about a Half hour and I will bet the Battry would be deader than Nails if the Headlight relay were to stay closed and not drop out.

Edited August 1, 2013 at 05:35 AM by Andre07

[larryh]

The charge extracted from the battery in the graph above is about 21.7 Ah.  That is far less than 650 Ah for a normal deep cycle car battery.  But this battery does not have to crank a starter to start the ICE.  The HVB starts the ICE.  The engineers at Ford must have analyzed the power requirements for the battery and determined that this one was adequate under a given set of assumptions.  However, the assumptions may have been too optimistic for the way the car is actually used or they failed to consider all contingencies.

 

The HVB must be carefully monitored and controlled by the battery control module.  That is a very expensive battery and you don't want to damage it.  For example, the battery temperature must not exceed 113 degrees F.  Something has to power the battery control module to control the energy being extracted from that battery.  The energy cannot be extracted until the control module is powered up.  The only way to do that is to use a separate 12 V battery. 

Edited August 1, 2013 at 10:42 AM by larryh

[murphy]

After the test was complete I disconnected the load resistor and connected my battery charger.  It initially indicated the charge level was 15% but within 2 minutes it jumped to 33%.  It then increased 1% at a time to 100% over about 5 hours.

 

When I removed the battery from the car I installed a Bosch battery of the size used in the gasoline only version of the Fusion (BXT-96R-590).

It was a tough fit because the battery is longer and doesn't fit in the battery tray.  I also had to extend the battery vent tube.  I immediately noticed that the power ports didn't shut off when the driver's door was opened after turning off the car.  I don't know what the timeout is for the power ports but at my first destination yesterday morning they stayed on for over an hour.

 

My 2010 Fusion hybrid had the same problem with the 12 volt battery, which was a BXT-57R-390 I think.

 

Does anyone know if the gasoline only 2013 Fusion also has the battery in the trunk or if it is in the engine compartment?

If I could find the proper battery tray I would leave the bigger battery in the car for a while to see how it performs. 

It is a starting battery so is not ideal for this service which needs an AGM or deep cycle battery.

[mczajka]

Great work! This kinda reminds me of the scene in the Apollo 13 movie when they were trying to figure out how much power the lunar module needed to get back up. We need some Ford engineers to start looking at this website and providing feedback.

[Eric4539]

Hey murphy, the gas engine Fusions all show the battery up front....

[Andre07]

When I removed the battery from the car I installed a Bosch battery of the size used in the gasoline only version of the Fusion (BXT-96R-590).

It was a tough fit because the battery is longer and doesn't fit in the battery tray.  I also had to extend the battery vent tube.  I immediately noticed that the power ports didn't shut off when the driver's door was opened after turning off the car.  I don't know what the timeout is for the power ports but at my first destination yesterday morning they stayed on for over an hour.

 

My 2010 Fusion hybrid had the same problem with the 12 volt battery, which was a BXT-57R-390 I think.

 

Could you please post the Physical Size of the BXT-99R-390 (WxDxH) so we can check to see if there may be any other Battery Types or Groups/Series with a higher Ampicity that can be used.  Is the Positive on the right or Left side of the Battery with the post at the front of the Battery.

Edited August 1, 2013 at 03:48 PM by Andre07

[murphy]

The positive post is on the right as indicated by the 99R designation.

The main section of the battery is 7-1/2" wide by 6-1/2" deep.
It is 6-7/8" high.
At the base there are 1/4" protrusions on all four sides for clamping the battery in place.  These extend beyond the above dimensions.
The one that is used for clamping is the one at the negative end of the battery.
The top area of the battery is 8-1/8" wide by 6-7/8" deep.
 

[murphy]

After the battery sat disconnected all night I hooked up the charger and it indicated a 90% charge level.

When it was back up to 100% charge level I hooked up my load tester and hit it with a 100 ampere load for 10 seconds.  It passed the load test no problem.  So high current testing says it is a good battery.

I reconnected the charger and got a 90% charge level.  That seems reasonable for the high current test.

I got the following character strings from the battery.  They are engraved into the plastic.

01653100
CA5AA<
3C03CACB
3C14A61

Does anyone know if there is a manufacturing date encoded in there?
 

[shaggy314]

I really find it strange why Ford would even bother to use a Lead Acid Battery for the Control Voltage when the HVB could have a 12 Volt Tap off it to operate the 12 Volt System.  Since the Computer will start the ICE when the HVB has less been depleted overver 6 KWh as has been posted by a few Members here.

 

I recall seeing it SOMEWHERE... but I believe Ford uses the 12 vt battery for safety. In all modes but run, the HVB is disconnected, so sitting there, accidents, acc mode; the HVB is isolated. Other than that, I cannot thin why have the extra system, wired, and engineering headache.

[Zman11]

Just saw this discussion at  cmaxenergiforum http://fordcmaxenergiforum.com/topic/1645-12-volt-battery-soc/

 

 

[Eric4539]

Wow! That was an interesting read. Thanks Zman11.

 

You know I have one of these Schumacher chargers sitting on the shelf so I suppose I should hook it up and see what my 12v battery shows.

[pluggedin]

Wow! That was an interesting read. Thanks Zman11.

 

You know I have one of these Schumacher chargers sitting on the shelf so I suppose I should hook it up and see what my 12v battery shows.

The Schumacher 2/10/15 charger is what I purchased last week before I took my car to my dealer for that bogus Sync upgrade. I also purchased a battery monitor that plugs into the cigarette lighter at the same time.

 

Both of those devices showed the battery voltage was 12.4 to 12.5v and, at times, as low as 11.9v. Generally speaking, the battery monitor reads 12.0-12.1v, however. Now, according to Schumacher, the battery is in a state of discharge at 11.9v and the battery needs to be charged when the reading is between 12.0 and 12.8v. However, the dealer goes by CCA only and they tested the battery, twice, at 390 CCA's and said the battery is good. They did not want to discuss voltage at all.

 

My car has been plugged in and fully charged since yesterday evening so just now I tested the voltage with the battery monitor and it registered 11.7v just after I closed the door and the dash display went out...then it went to 12.0v after about minute. I disconnected the 240v charger from the vehicle and attached the Schumacher battery charger to the battery posts under the hood. The reading was 12.1v (there is usually .1v difference between the two). I put the charger in a moderate charge rate and the charger indicated the battery was currently in a 62% state of charge so I am letting the charger bring the battery to 100% for the second time this week.

 

Here is what I think the problem is in communicating our concerns about the battery voltage to the dealership technicians. They are used to working on gasoline engine and batteries that are used to crank the engines over to start them; hence they want to talk in terms of CCA's. The plug-in hybrid is a different animal, with respect to how the battery is used by the system, from the gasoline models and I think we, on the forum, understand the system better than they do. How to educate them so we don't run into a stone wall every time we talk to them about an Energi is the question.

 

I just find it unacceptable that I have to buy a device to monitor the voltage in my 12v battery and that I also need to buy a battery charger to keep the 12v battery in a state of full charge. Maybe I should have been doing this with all of the cars I have owned in my life but I have never, ever, found it to be a necessity.

[Andre07]

I removed the battery from my car and fully charged it.

I then put a 15 ohm 10 watt resistor across the battery and measured the voltage at one minute intervals for 1703 minutes (28 hours and 23 minutes) using a computer controlled voltmeter.  15 ohms across 12 volts is 0.8 ampere.  As the voltage drops the current also drops.

 

Note how quickly the voltage drops below 12 volts.

 

BXT-99R-390-S.jpg

 

 

It's no wonder the car goes into battery preservation mode.

Thanks for the Graph murphy, great work.

 

Any idea at what voltage on the 12 Volt Battery, the car goes into BPM,  Battery Preservation Mode?

 

I wonder how this Battery that Ford decided to use compares with other Lead Acid Batteries or AGM batteries

 

I will try post a Amp Hour Graph for this battery from info displayed on your Graph.

 

From your Graph, if we start at 12.2 V using your 15 ohm Resistor we can determine how much current is drawn and with that how much Power the Battery is storing and what reserve capacity.  This is done is 30 Min intervals as depicted by the Graph.

 

Attachment to follow:

Edited August 31, 2013 at 05:14 PM by Andre07

[Eric4539]

I have the Schumacher SC-1200A 12/8/2.  Should be fine right?

 

 

12 Amp fast charge to monitor battery condition and prevent battery damage

8 Amp medium charge to self-adjust charge rate and keep the battery in peak condition

2 amp slow charge to charge small and maintain large batteries

[pluggedin]

I have the Schumacher SC-1200A 12/8/2.  Should be fine right?

 

 

12 Amp fast charge to monitor battery condition and prevent battery damage

8 Amp medium charge to self-adjust charge rate and keep the battery in peak condition

2 amp slow charge to charge small and maintain large batteries

Others on this forum are better qualified to respond to this but I think your charger will work just fine, just a tiny bit slower charge time than mine.

[pluggedin]

Thanks for the Graph murphy, great work.

 

Any idea at what voltage on the 12 Volt Battery, the car goes into BPM,  Battery Preservation Mode?

 

I wonder how this Battery that Ford decided to use compares with other Lead Acid Batteries or AGM batteries

 

I will try post a Amp Hour Graph for this battery from info displayed on your Graph.

 

From your Graph, if we start at 12.2 V using your 15 ohm Resistor we can determine how much current is drawn and with that how much Power the Battery is storing and what reserve capacity.  This is done is 30 Min intervals as depicted by the Graph.

 

Attachment to follow:

I'm not sure if this question is different or not. What is the minimum voltage the 12v battery needs to have for the system to operate, before it begins to go hay wire or not start at all?

[Andre07]

I have the Schumacher SC-1200A 12/8/2.  Should be fine right?

 

 

12 Amp fast charge to monitor battery condition and prevent battery damage

8 Amp medium charge to self-adjust charge rate and keep the battery in peak condition

2 amp slow charge to charge small and maintain large batteries

This Charger is fine

 

Set it for 12 Amp Mode for quicker Charge,

 

For overnight charging you can set it for 8 amp mode

 

2 Amp is for tinkle Charge  good for Storange Batteries  that are only use periodically

[Eric4539]

Thanks Andre07 and pluggedin!  I am going to test the voltage and then charge my battery.

[Andre07]

Thanks Andre07 and pluggedin!  I am going to test the voltage and then charge my battery.

If you have a Battery tester (one that plugs into the Lighter)  please leave it on and report what voltage you see before you start charging, what the rate is when charging  and what it it is when you pull the charger off and what it reads 5, 10, 15, 20 minutes after

 

I am sure others may be interested what you observe and report.

Edited August 31, 2013 at 06:57 PM by Andre07

[murphy]

I'm not sure if this question is different or not. What is the minimum voltage the 12v battery needs to have for the system to operate, before it begins to go hay wire or not start at all?

The lowest voltage I have seen is 11.1 volts.  The car goes into run mode fine but the radio can't be turned on by itself.  When the battery is this low turning on accessory mode (push the start button without foot on brake pedal) does not turn on the center stack or the power outlets and charging does not start.  Almost immediately the battery saver messages appears and after the progress bar completes the car shuts down.

 

I have a battery tester that puts a 100 ampere load on the battery for 10 seconds and shows the voltage.  The voltage must stay above 11 volts at the end of the 10 seconds for the battery to be considered good.  The test is done after the battery is charged to 100%.

 

My battery passes this test but this is a "starter" battery test and doesn't say much for the condition of an AGM battery.