12V battery usage (volts) for various functions & situations in Mach-E

JamieGeek · Feb 16, 2021

Since I have one of those cigarette lighter meters (Amazon); I figured I would take some measurements of the LVB battery in various car states:

Start up Mach-E: 15V
Steady state (I'm guessing after it determines that the 12V battery is full): 13.5V (float charge to keep the 12V battery full)
Off: Off
Plug in to charge: 15V
Charging: 13.5V
After charging complete: Off
Remote start: Off (makes sense that the socket would be off since all the screens are off)
Accessory mode, plugged in: 15V (This would indicate that the DC-DC is on and the HVB contactors are closed. Still, however, the HVAC doesn't turn on the heaters as I've sat in the car like this for some time and it just blows cold air...brrr)
Accessory mode, not plugged in: 14.8V (interesting either DC-DC isn't set to 15V in this case or there is significant draw).
Driving: 12.9V

I haven't read it while driving since I haven't had the car out since I plugged in the meter (and won't today with lots of snow around here).

So far my LVB seems to be in good shape as its reading 12.5V when the DC-DC is off (right at startup before the DC-DC turns on you can see the LVB's reading).

ChasingCoral · Feb 16, 2021

I've seen my Instrument Panel display a message that was something like FULL ACCESSORY POWER ON. Are there perhaps two different accessory power modes with one activating some systems and the other activating more? The other option is that's just the car's way of saying Accessory Power is on.

JamieGeek · Feb 16, 2021

ChasingCoral said:
I've seen my Instrument Panel display a message that was something like FULL ACCESSORY POWER ON. Are there perhaps two different accessory power modes with one activating some systems and the other activating more? The other option is that's just the car's way of saying Accessory Power is on.

Yeah that is what I see when I press the start button without foot on the brake. Not sure why "Full" is there as that would imply (what you're saying) that there is another mode with partial power.

I'll also note that when in "Full Accessory Power" mode the start button's green light flashes.

Shayne · Feb 16, 2021

Admin: please Sticky this

Repost:

Looking at combinations. Remote start when plugged in charging, plug in not charging, and when not plugged in. The combination go on and on. So.

After charging complete: Off and
- Remote start: off--all displays are off so I'd expect the cig lighter sockets to be off as well.

Some could be charging the 12v but no power to the cigarette lighter. That would be a conservative error until further info.

So after you charge it to your preferred charge level and then remote start it stands to reason it is not charging the 12V and not a double negative. You would think the connection should be made to the 12v during start up and charge it. It's is not the sky is falling type of problem but it is not something I am not willing to live with forever. Could be a simple software tweak that fixes this problem. Power drain on the MME is now like FordPass had.

Shayne · Feb 16, 2021

ChasingCoral said:
I've seen my Instrument Panel display a message that was something like FULL ACCESSORY POWER ON. Are there perhaps two different accessory power modes with one activating some systems and the other activating more? The other option is that's just the car's way of saying Accessory Power is on.

your vids and my pics are pretty close. https://www.macheforum.com/site/threads/repopulate-previous-locations.3368/page-2#post-107524
Did not like you popping pin and cracking cover storey to much.

GoGoGadgetMachE · Feb 16, 2021

JamieGeek said:
Yeah that is what I see when I press the start button without foot on the brake. Not sure why "Full" is there as that would imply (what you're saying) that there is another mode with partial power.

I'll also note that when in "Full Accessory Power" mode the start button's green light flashes.

the flashing Start button green light is something ISTR from my Fusion Energi as well although I'm too lazy to walk to the car right now and check it.

jeffdawgfan · Feb 16, 2021

GoGoGadgetMachE said:
the flashing Start button green light is something ISTR from my Fusion Energi as well although I'm too lazy to walk to the car right now and check it.

I noticed the flashing green button when i took my test drive the other day. All the displays were lit up but shift knob would not turn. That is how I figured out the flashing light meant just accessory power on. I thought something was wrong with shifter.

Metal_Horses · Feb 16, 2021

ChasingCoral said:
I've seen my Instrument Panel display a message that was something like FULL ACCESSORY POWER ON. Are there perhaps two different accessory power modes with one activating some systems and the other activating more? The other option is that's just the car's way of saying Accessory Power is on.

It would be nice if there was an all school "Accessory" mode for power. Or as I call it: "Drive-in Movie" mode ?

sockmeister · Feb 16, 2021

I'd be curious to see if the voltage while off drops significantly while sitting overnight in the cold. (From 12.5V)

JamieGeek · Feb 16, 2021

sockmeister said:
I'd be curious to see if the voltage while off drops significantly while sitting overnight in the cold. (From 12.5V)

I haven't seen that but my car was plugged in overnight.

Throughout the day today I've noticed the car warming the HVB in the garage. Twice I've gone out there and heard the pumps running and noticed that the EVSE contactors had been closed for a good 20 minutes (display on my JuiceBox shows that).

My garage hoovers just above freezing in cold weather like this.

sockmeister · Feb 16, 2021

JamieGeek said:
I haven't seen that but my car was plugged in overnight.

Throughout the day today I've noticed the car warming the HVB in the garage. Twice I've gone out there and heard the pumps running and noticed that the EVSE contactors had been closed for a good 20 minutes (display on my JuiceBox shows that).

My garage hoovers just above freezing in cold weather like this.

That sounds normal, but if you do happen to have your car sit in the cold for several hours, I wonder if the 12v would slowly lose charge (maybe the Mach-E isn't charging it like it's supposed to while sitting?)

RVAtom · Feb 17, 2021

Metal_Horses said:
It would be nice if there was an all school "Accessory" mode for power. Or as I call it: "Drive-in Movie" mode ?

We have a drive in nearby and I too would like this mode. It seems like the MME would be a great drive in car.

generaltso · Feb 17, 2021

RVAtom said:
We have a drive in nearby and I too would like this mode. It seems like the MME would be a great drive in car.

Since there's no engine running, couldn't you just leave the car in full "Ready" mode at the drive-in?

Marcel · Feb 17, 2021

generaltso said:
Since there's no engine running, couldn't you just leave the car in full "Ready" mode at the drive-in?

that is how I used it at the drive-in, just on in P.....

JamieGeek · Feb 17, 2021

While driving: 12.9V

I would imagine there is some load on the system while you're going down the road.

12V battery usage (volts) for various functions & situations in Mach-E

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