How to DIY - add access holes for LVB 12v battery connection points & HV Disconnect Relay for Safety

[Ride_the_lightning]

I did a test and while plugged in, the car does maintain the LVB. But when unplugged, it does not. Of course that should not be an issue unless there is something draining the battery.

When unplugged, my car did nothing to save the battery until I plugged it back in.

This is exactly what I am thinking. It does not hurt to run it for a couple days just to be sure the battery is performing as it should.

What in the world drained your 12V battery so fast? Is that just the OBD2? In that case, isn’t the ECU active also since you are pulling data. Sounds like Schrödinger's cat.

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[mkhuffman]

What in the world drained your 12V battery so fast? Is that just the OBD2? In that case, isn’t the ECU active also since you are pulling data. Sounds like Schrödinger's cat.

Someone who knows more about this than me told me the OBDII scanner keeps various components alive in the car, which makes sense because it is reading data. The components that provide the data must be powered, otherwise - no data!

So it is not the scanner, it is how the car reacts to the scanner that kills the battery.

 

[dtbaker61]

Someone who knows more about this than me told me the OBDII scanner keeps various components alive in the car, which makes sense because it is reading data. The components that provide the data must be powered, otherwise - no data!

So it is not the scanner, it is how the car reacts to the scanner that kills the battery.

the battery *should not* be killed regardless of whether MME is plugged in or not, or on or not. If functioning correctly the LVB is supposed to get checked, and wake up the HV charger when and if LVB drops below 11.9 volts.

 

[mkhuffman]

the battery *should not* be killed regardless of whether MME is plugged in or not, or on or not. If functioning correctly the LVB is supposed to get checked, and wake up the HV charger when and if LVB drops below 11.9 volts.

I agree but testing indicates my car does not maintain the LVB when off and not charging.

 

[dtbaker61]

I agree but testing indicates my car does not maintain the LVB when off and not charging.

Have you asked your Dealer Service dept to ask Ford Field Engr if this is 'expected behavior' ? maybe they can check to see if your VIN needs some module(s) updated?

I have not run a continuous ODB datalogger on mine, but I did leave the hood up, let it go into deep sleep overnight while UNplugged, and snuck up to check voltage directly w voltmeter at connection points without my phone to wake up the MME... never saw a voltage below 12.2 in the morning, so assuming it maintained overnight if and when needed.

 

[mkhuffman]

Have you asked your Dealer Service dept to ask Ford Field Engr if this is 'expected behavior' ? maybe they can check to see if your VIN needs some module(s) updated?

I have not run a continuous ODB datalogger on mine, but I did leave the hood up, let it go into deep sleep overnight while UNplugged, and snuck up to check voltage directly w voltmeter at connection points without my phone to wake up the MME... never saw a voltage below 12.2 in the morning, so assuming it maintained overnight if and when needed.

I am taking my car in on Monday for another issue and I am expecting them to update all the modules. I have a list of the ones that need updating. I will do another test after I confirm my modules are up to date.

 

[generaltso]

I agree but testing indicates my car does not maintain the LVB when off and not charging.

That's definitely not the way it's supposed to work. I've seen the DC/DC converter kick on several times in my car when off plug. It generates the lovely "12V Fault" alert every time, immediately followed by 15V.

 

[mkhuffman]

That's definitely not the way it's supposed to work. I've seen the DC/DC converter kick on several times in my car when off plug. It generates the lovely "12V Fault" alert every time, immediately followed by 15V.

It is possible that would have happened if I let it keep going. I was worried about the LVB and also I needed to charge the car. Maybe if it got below 10% it would have kicked in.

 

[generaltso]

It is possible that would have happened if I let it keep going. I was worried about the LVB and also I needed to charge the car. Maybe if it got below 10% it would have kicked in.

If it's working correctly, the DC/DC converter should kick on immediately if the LVB reaches 30% SOC.

 

[dtbaker61]

I agree but testing indicates my car does not maintain the LVB when off and not charging.

if you ever see anything less than 12.0 when the MME is sleeping with no loads on (not even the frunk light), then something is definitely wrong.

I double checked mine last night:
- MME = OFF in garage, not plugged in, HV at 65%
- phone - BT and FordPass OFF so I can sneak up on MME without it waking up
- popped hood up
- popped LVB access hole covers off so I can check voltage without ODB waking up car
- waited 15 minutes, frunk light = off
LVB = 12.36v at 9:45pm
- this morning....
LVB = 12.43v at 8:00am
LVB = 12.42v at 10:00am

.... so I'd guess at some point during the night it got a little bump up from the HV

 

[Chuck]

if you ever see anything less than 12.0 when the MME is sleeping with no loads on (not even the frunk light), then something is definitely wrong.

I double checked mine last night:
- MME = OFF in garage, not plugged in, HV at 65%
- phone - BT and FordPass OFF so I can sneak up on MME without it waking up
- popped hood up
- popped LVB access hole covers off so I can check voltage without ODB waking up car
- waited 15 minutes, frunk light = off
LVB = 12.36v at 9:45pm
- this morning....
LVB = 12.43v at 8:00am
LVB = 12.42v at 10:00am

.... so I'd guess at some point during the night it got a little bump up from the HV

My battery is generally 14.60 volts when I get in the car.

 

[generaltso]

My battery is generally 14.60 volts when I get in the car.

That means the DC/DC converter is on.

 

[RockwallRick]

if you ever see anything less than 12.0 when the MME is sleeping with no loads on (not even the frunk light), then something is definitely wrong.

I double checked mine last night:
- MME = OFF in garage, not plugged in, HV at 65%
- phone - BT and FordPass OFF so I can sneak up on MME without it waking up
- popped hood up
- popped LVB access hole covers off so I can check voltage without ODB waking up car
- waited 15 minutes, frunk light = off
LVB = 12.36v at 9:45pm
- this morning....
LVB = 12.43v at 8:00am
LVB = 12.42v at 10:00am

.... so I'd guess at some point during the night it got a little bump up from the HV

Don’t you have to wake up the car to pop the hood? Just for comparison I’ve observed my Truck Battery dropping as low as 11.6v and it still cranks up for me!

 

[generaltso]

Don’t you have to wake up the car to pop the hood?

Not if you leave the hood open.

 

[hawkeye3point1]

Not if you leave the hood open.

The OCD part of me wants to know if there is a way to turn off the frunk light with the hood unlatched?

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