LV battery maintenance

[rzanzerkia]

I bought my Mach-E only 8 days ago.
It was one of those stuck at rail yards (I believe it's October build)
Unlike some folks my 12V battery was not dead on arrival.
I picked up the car on Jan 14th and have had no issues (plugged in 110V every night).
Wife drives around 6 mile RT every day.

Since I read problems with LV battery (particularly on older builds), I bought the battery monitor from Amazon.
Here are the readings.
Car was turned off but main screen on reading 12.23-12.24V
When car turned off the interior lights and everything 12.43V
According to the graph on the meter it's 50-75% range.

Questions:
Is this a normal range?
Do I need to trickle charge battery to pre-condition and bring it up to 100% level (12.6V)?

Temps are cold here 20s.

 

[RockwallRick]

Not that cold here but those readings look about normal to me. I am using the same monitor for battery checks.

 

[macchiaz-o]

It looks fine. I wouldn't worry about it.

Voltage when at full state of charge depends on temperature, load, and "secret sauce" factors of the specific battery's construction.

I was running my car seemingly fine until the battery got down to about 8.7V. (Don't do that... I didn't mean to do that.)

When you're driving, you may notice higher voltages such as 13.x or 14.6 or whatnot... The DC-DC converter is powering the 12V bus when you see that.

 

[louibluey]

12.3V is really common with MME system running. If you leave the frunk open for a bit (MME OFF), when the frunk light goes out, that is rest or sleep (not deep sleep). Then you might see the voltage pop up to 12.5V, but I guess the 12V accessory port turns off too.

The normal DC/DC converter voltage is 13.4V at warm ambient temps, low converter loads, good LVB charge. It can go as high as 15.5V (some read 15.6V) at higher loads, colder conditions.

The battery itself as I understand it cannot of its own (e.g. at rest, disconnected) go above 13V, but you will often it see it settling from 13.4 or higher. A 100% soc MME 12V LVB reads 13V (e.g. out of MME on the bench).

There are a variety of conditions on how and when MME charges LVB, sometimes by the DC/DC converter powered by the high voltage traction battery, sometimes by the DC/DC converter powered directly by the high voltage output of the charger in the car when plugged in for AC charging.

What is odd, is that the MME designers apparently designed MME to cycle the LVB through discharge and charge cycles, kind of like we discharge and charge the HVB, in some circumstances, letting it fall to as low as 35%/40% charge (which lately generates a Fordpass warning, "Service 12V LVB"), then charging it back up to 90%/100%. Under some conditions, I have seen 12.1V to 11.9V as the "normal" low point range before MME took over and started to recharge LVB on its own.

It is very common to see 12.3V loaded (MME ON) no matter what you did before (charge, drive, 12V trickle/charge, etc.), so something draws the LVB down. Unclear if that is a problem, or just the way MME works.

A normally properly operating MME (not broken) will recharge the LVB driving/plugged in/unplugged as needed. The maintenance rules vary depending on the situation, e.g. plugged in or not.

(The chart on the rear of the meter is not for AGM LVB where ~13V is 100%)

Sponsored