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Discussion Starter #1
Ok guys, been a while since ive posted..

So I wasn't able to make focus fest due to this damn batter light..

heres what ive done:

Tested alternator, passed.
Battery still motercraft test, 54%: replaced battery
Thought it was voltage regulator used an old school load tester that isolates anything and drops a massive load on the system, noticed dropping to 13 but going back up to 14 volts...

I have toms tune, called tom and was like what could be going on thinking it could be the tune. He updated my log list to include battery voltage and desired voltage values so I could monitor them.

Held rev limiter at 3k for 2 minutes to put a load on. car was charging

Then after these tests I assumed it was overcharging and it would fix itself by dropping down to the nessarry voltage and then the light would come back.

--- battery light went away for about a month and a half and came back yesterday.

So I monitored the voltage again thru Live link, and noticed its charging... not sure what could be the problem, still charging under load based on live link data logging...

Ive attached a couple videos showing how live link reads my exact voltage values for peer review.

Would like to pick peoples brains here and figure out what could be causing this light to come out because ive checked just about everything I could think that normally associates tripping the battery light.

Please and thank you for the help.

** Also seriously bummed and heartbroken that I couldn't make focusfest this year having planned and built my car 8 months before hand. Hope I can make the next one and everyone had a good time**

Video links
Battery test 1: notice it says desired voltage is 14.8v
https://www.youtube.com/watch?v=DQT63NeOOh0

Battery test 2: notice somehow the desired voltage increased to 15v
https://www.youtube.com/watch?v=b2rjVN8_jSQ

Thanks,
Armysniper10
 

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Discussion Starter #3
You didn't mention if you checked the belt.
Other than wiring and connectors not much else to check.
Battery terminals are secure and cant really tell the connection on the alternator but yea just doesn't make any sense..

bets are good no squeeking and its charging during load so i guess that eliminates the pully too but yea its charging so i assume the bekts are rotating just fine
 

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Battery terminals are secure and cant really tell the connection on the alternator but yea just doesn't make any sense..

bets are good no squeeking and its charging during load so i guess that eliminates the pully too but yea its charging so i assume the bekts are rotating just fine
Worn belts don't always squeak, to see if its stretched check to see if the belt is sitting on the grooves( not bottomed out into the groove) not in them. If it sitting in the grooves(bottom of rib touching bottom of groove in pulley) its stretched.
 

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Old Phart
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Earlier models have a "Battery" fuse (small one) that's for the charging system sensor arrangement, it'll still work fine with that one blown/bad connection but the light will always be on.

Might check if something similar exists in the MkIII.
 

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Focus Preacher
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3,408 Posts
Ok guys, been a while since ive posted..

So I wasn't able to make FocusFest due to this damn batter light..

heres what ive done:

Tested alternator, passed.
Battery still motercraft test, 54%: replaced battery
Thought it was voltage regulator used an old school load tester that isolates anything and drops a massive load on the system, noticed dropping to 13 but going back up to 14 volts...

I have toms tune, called tom and was like what could be going on thinking it could be the tune. He updated my log list to include battery voltage and desired voltage values so I could monitor them.

Held rev limiter at 3k for 2 minutes to put a load on. car was charging

Then after these tests I assumed it was overcharging and it would fix itself by dropping down to the nessarry voltage and then the light would come back.

--- battery light went away for about a month and a half and came back yesterday.

So I monitored the voltage again thru Live link, and noticed its charging... not sure what could be the problem, still charging under load based on live link data logging...

Ive attached a couple videos showing how live link reads my exact voltage values for peer review.

Would like to pick peoples brains here and figure out what could be causing this light to come out because ive checked just about everything I could think that normally associates tripping the battery light.

Please and thank you for the help.

** Also seriously bummed and heartbroken that I couldn't make focusfest this year having planned and built my car 8 months before hand. Hope I can make the next one and everyone had a good time**

Video links
Battery test 1: notice it says desired voltage is 14.8v
https://www.youtube.com/watch?v=DQT63NeOOh0

Battery test 2: notice somehow the desired voltage increased to 15v
https://www.youtube.com/watch?v=b2rjVN8_jSQ

Thanks,
Armysniper10

Disconnect your battery load sensor... and see if it improves (100% charging all the time no more load shedding)


EDIT: I fail to see the problem... there is no normal car voltage... it all depend on the car electrical load & supply... 14.7V is de-facto voltage... I don't see 15V there... it tops out at 14.88 MAX well within tolerance.

EDIT2: any B codes ?
 

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I fail to see the problem... there is no normal car voltage... it all depend on the car electrical load & supply
True, the smart charging system can vary the voltage from 12.8 up to 14.8 volts and you do not have to rev the motor to 3000 rpm to attain higher voltage. The MK3 is typically at 13.8+ volts at idle when you first start the car and the voltage will typically ramp down after a minute or so.
 

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Discussion Starter #8
I fail to see the problem... there is no normal car voltage... it all depend on the car electrical load & supply
True, the smart charging system can vary the voltage from 12.8 up to 14.8 volts and you do not have to rev the motor to 3000 rpm to attain higher voltage. The MK3 is typically at 13.8+ volts at idle when you first start the car and the voltage will typically ramp down after a minute or so.
Ok guys, been a while since ive posted..

So I wasn't able to make FocusFest due to this damn batter light..

heres what ive done:

Tested alternator, passed.
Battery still motercraft test, 54%: replaced battery
Thought it was voltage regulator used an old school load tester that isolates anything and drops a massive load on the system, noticed dropping to 13 but going back up to 14 volts...

I have toms tune, called tom and was like what could be going on thinking it could be the tune. He updated my log list to include battery voltage and desired voltage values so I could monitor them.

Held rev limiter at 3k for 2 minutes to put a load on. car was charging

Then after these tests I assumed it was overcharging and it would fix itself by dropping down to the nessarry voltage and then the light would come back.

--- battery light went away for about a month and a half and came back yesterday.

So I monitored the voltage again thru Live link, and noticed its charging... not sure what could be the problem, still charging under load based on live link data logging...

Ive attached a couple videos showing how live link reads my exact voltage values for peer review.

Would like to pick peoples brains here and figure out what could be causing this light to come out because ive checked just about everything I could think that normally associates tripping the battery light.

Please and thank you for the help.

** Also seriously bummed and heartbroken that I couldn't make focusfest this year having planned and built my car 8 months before hand. Hope I can make the next one and everyone had a good time**

Video links
Battery test 1: notice it says desired voltage is 14.8v
https://www.youtube.com/watch?v=DQT63NeOOh0

Battery test 2: notice somehow the desired voltage increased to 15v
https://www.youtube.com/watch?v=b2rjVN8_jSQ

Thanks,
Armysniper10

Disconnect your battery load sensor... and see if it improves (100% charging all the time no more load shedding)


EDIT: I fail to see the problem... there is no normal car voltage... it all depend on the car electrical load & supply... 14.7V is de-facto voltage... I don't see 15V there... it tops out at 14.88 MAX well within tolerance.

EDIT2: any B codes ?
Ok body code is one but that is because i ripped out the shutter system.. i wanted more air flow but that is it for the b code.. if i am assuming correct a b code is a body code right?

either way the codes that were thrown were due to mods ive made so nothing that should throw the code cuz they were done when no problem exisited.. i will check the fuse look at the manual later tonight. I have cree leds now but did hVe hids.. i have auxiliary lights and a subwoofer so def more voltage then stock needed.. hence makes sense with the smart voltage thingy that was mentioned.. however i have noticed that when driving sometimes the airbag light comes on and goes off seems to only happen when the battery light is on.. but i havent modified anything airbag wise only too off the airbag to wrap center wheel trim but took extra care t make sure 110% that connector was put back right and not broken. Either way its mind blowing becuase it just seemingly dpesnt make sense unless i start dumping money into a new alternator beltd and everything for no reason..
 

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Focus Preacher
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Also at the risk of sounding stupid what is the battery load sensor that ur talking about disconnecting?
BMS sensor is located on the negative battery terminal...unplug it it will make the charging system work all the time instead of load shedding.

At 9:56 in the video the sensor is the one with the 2 wires.


EDIT:

Ok body code is one but that is because i ripped out the shutter system.. i wanted more air flow but that is it for the b code.. if i am assuming correct a b code is a body code right?
Yeah, if charging problems occurs they will show under B DTC

ex:

B1317: Battery voltage high (greater than 16V)
B1318:Battery voltage low (less than 10V)
 

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Discussion Starter #11
Also at the risk of sounding stupid what is the battery load sensor that ur talking about disconnecting?
BMS sensor is located on the negative battery terminal...unplug it it will make the charging system work all the time instead of load shedding.

At 9:56 in the video the sensor is the one with the 2 wires.


EDIT:

Ok body code is one but that is because i ripped out the shutter system.. i wanted more air flow but that is it for the b code.. if i am assuming correct a b code is a body code right?
Yeah, if charging problems occurs they will show under B DTC

ex:

B1317: Battery voltage high (greater than 16V)
B1318:Battery voltage low (less than 10V)

Ok yea im def sure i dont have a b code for anything battery which is a good sign.. and would always charging vs load shedding be detrimental sorta like the same concept of constantly having ur phone or laptop charged.. would it in affect create a memory in the car? would that cause any problems? or just halflife ur alternator?
 

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Focus Preacher
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Ok yea im def sure i dont have a b code for anything battery which is a good sign.. and would always charging vs load shedding be detrimental sorta like the same concept of constantly having ur phone or laptop charged.. would it in affect create a memory in the car? would that cause any problems? or just halflife ur alternator?
No, load shedding exist (intelligent charging) to save fuel.

Before that it was a dumb charging system which the alternator was always activated.

Now with the Battery Monitoring System (very very simplified version):

It will disengage the alternator on idle to save fuel (shed engine load)

Will only re-engage the charging when battery is below a state of charge threshold.

Will activated the alternator on down hill (regenerative charging)

IIRC, unless electrical load is high... it will also turn off the alternator on WOT.

etc etc



EDIT: If you like reading


This vehicle is equipped with a Electrical Energy Management system which manages battery charging by the generator and
monitors the battery state of charge.

The Electrical Energy Management system also utilizes a load shed strategy to help control
discharge of the battery and prevent, when possible, an excessively low battery state of charge.

The BCM monitors the battery state of charge using the battery monitoring sensor attached to the negative battery terminal.
To maintain correct operation of the load shed system, any electrical devices or equipment must be grounded to the chassis
ground and not the negative battery terminal. A connection to the negative battery terminal causes an inaccurate measurement
of the battery state of charge and incorrect load shed system operation due to the current being used bypassing the battery
monitoring sensor.

When the ignition is in ACC or ON mode and the BCM determines the battery voltage or the battery state of charge has dropped
below set levels, a low battery warning message is displayed in the message center. Should the battery voltage or the batterystate of charge continue to drop, the audio system is powered down to save the remaining battery charge. This load shed state
clears once the vehicle is started and battery state of charge is allowed to recover.

When the ignition is in the ON mode and if load shed occurs, the message center displays the corresponding message to notify
the driver that battery protection actions are active. The audio system shuts down after the message center displays the
warning.

If a fault occurs with the battery monitoring sensor or circuit(s), the only engine off load shed strategy that is active is a 45
minute timer. After 45 minutes have elapsed, the audio system turns off. To clear the load shed state, restart the engine.
If the vehicle battery is replaced, carry out the Battery Monitoring System Reset using the scan tool.

If the Battery Monitoring System Reset is not carried out, measurement data collected for the old battery is not deleted and future state of charge
measurements will be inaccurate. For example, if an old battery has a state of charge of 60% and the new battery has a state of
charge of 90%, the BCM will recognize battery state of charge being 30% lower than it actually is. With the battery state of
charge being perceived lower than it actually is causes shedding of loads earlier than is necessary. This also impacts the smart
regenerative charge system by causing the battery to be maintained at a higher state of charge than perceived by the BCM ,
reducing fuel economy benefits.
 

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138 Posts
Discussion Starter #13
Ok yea im def sure i dont have a b code for anything battery which is a good sign.. and would always charging vs load shedding be detrimental sorta like the same concept of constantly having ur phone or laptop charged.. would it in affect create a memory in the car? would that cause any problems? or just halflife ur alternator?
No, load shedding exist (intelligent charging) to save fuel.

Before that it was a dumb charging system which the alternator was always activated.

Now with the Battery Monitoring System (very very simplified version):

It will disengage the alternator on idle to save fuel (shed engine load)

Will only re-engage the charging when battery is below a state of charge threshold.

Will activated the alternator on down hill (regenerative charging)

IIRC, unless electrical load is high... it will also turn off the alternator on WOT.

etc etc



EDIT: If you like reading


This vehicle is equipped with a Electrical Energy Management system which manages battery charging by the generator and
monitors the battery state of charge.

The Electrical Energy Management system also utilizes a load shed strategy to help control
discharge of the battery and prevent, when possible, an excessively low battery state of charge.

The BCM monitors the battery state of charge using the battery monitoring sensor attached to the negative battery terminal.
To maintain correct operation of the load shed system, any electrical devices or equipment must be grounded to the chassis
ground and not the negative battery terminal. A connection to the negative battery terminal causes an inaccurate measurement
of the battery state of charge and incorrect load shed system operation due to the current being used bypassing the battery
monitoring sensor.

When the ignition is in ACC or ON mode and the BCM determines the battery voltage or the battery state of charge has dropped
below set levels, a low battery warning message is displayed in the message center. Should the battery voltage or the batterystate of charge continue to drop, the audio system is powered down to save the remaining battery charge. This load shed state
clears once the vehicle is started and battery state of charge is allowed to recover.

When the ignition is in the ON mode and if load shed occurs, the message center displays the corresponding message to notify
the driver that battery protection actions are active. The audio system shuts down after the message center displays the
warning.

If a fault occurs with the battery monitoring sensor or circuit(s), the only engine off load shed strategy that is active is a 45
minute timer. After 45 minutes have elapsed, the audio system turns off. To clear the load shed state, restart the engine.
If the vehicle battery is replaced, carry out the Battery Monitoring System Reset using the scan tool.

If the Battery Monitoring System Reset is not carried out, measurement data collected for the old battery is not deleted and future state of charge
measurements will be inaccurate. For example, if an old battery has a state of charge of 60% and the new battery has a state of
charge of 90%, the BCM will recognize battery state of charge being 30% lower than it actually is. With the battery state of
charge being perceived lower than it actually is causes shedding of loads earlier than is necessary. This also impacts the smart
regenerative charge system by causing the battery to be maintained at a higher state of charge than perceived by the BCM ,
reducing fuel economy benefits.

Well Damn thanks.. I appreciate the response .. extremly helpful and slightly impressed i need to pick ur guys Brians more often..

Soo basically disconnect intelli plug and should fix my problem?
 

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Old Phart
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44,596 Posts
That's a bypass, not a fix.

The BIG 'stupid" question is - has tth battery been replaced?

If the prev. one was in bad condition, and the system wasn't reset when the new one was installed, you MAY still be getting warnings for that CRAP battery instead of for load levels of the current battery.

In normal daily use, the car seldom sits long enough for the system to do a reset on it's own.
 

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138 Posts
Discussion Starter #15
That's a bypass, not a fix.

The BIG 'stupid" question is - has tth battery been replaced?

If the prev. one was in bad condition, and the system wasn't reset when the new one was installed, you MAY still be getting warnings for that CRAP battery instead of for load levels of the current battery.

In normal daily use, the car seldom sits long enough for the system to do a reset on it's own.
Definitely has a new battey.. and when i cleaned the throttle body i turned off all loads and let car ideal for 15 minutes to figure put idle flap degree position but never thought i had to reset the battery.. do u know how to do the proper reset to get rid of the crap battery load Sailor?
 

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Focus Preacher
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3,408 Posts
Definitely has a new battey.. and when i cleaned the throttle body i turned off all loads and let car ideal for 15 minutes to figure put idle flap degree position but never thought i had to reset the battery.. do u know how to do the proper reset to get rid of the crap battery load Sailor?
FORScan can do it...

The other method is letting the car 8+ hours without being touched.

But do the BMS reset with FORScan, it's like it would have been done at the dealer with IDS.
 

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Old Phart
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44,596 Posts
Take it to Ford Dealer, or buy the right software (app) for your phone along with a bluetooth dongle for the OBD port.

I've seen info. that it can reset, but it takes something like a day of sitting with NO load changes - don't even open a door.


Beat me to it Bud!!
 

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Discussion Starter #18
Take it to Ford Dealer, or buy the right software (app) for your phone along with a bluetooth dongle for the OBD port.

I've seen info. that it can reset, but it takes something like a day of sitting with NO load changes - don't even open a door.


Beat me to it Bud!!
I dont know what forscan is... lol

If im going to let it sit for a day.. do i need to disconnect the postive side of the battery?

Where can i get forscan is it cheap?
 

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574 Posts
Forscan is free to download(except mobile version, small donation), download the latest version you just need to buy the adapter to plug into your car. There are threads on it here.

www.forscan.org


You can't just disconnect the battery and hold the brake to reset this, has to be done either with forscan(or at dealer) or letting it sit untouched all day?

Edit: after going thru the service manual apparently not.
 

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Discussion Starter #20
Problem solved! BMS reset

Ok, so letting the car sit for 24 hours almost with no load seemed to fix the problem that seems to be caused by the BMS reset.

The solution of 8+ hours even though I decided I would do longer seemed to work, battery light gone and problem solved.. Its crazy how finicky the computers are.. thanks for the help everyone much appreciated like usual:)
 
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