12V Battery Status Indicator

[dtbaker61]

https://www.macheforum.com/site/thr...r-12v-battery-recommended-at-36-months.36526/

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[zvez]

again.... SOC does not reflect 'health'

I get that, but if a battery has a state of charge of 90% today, and 50% two days from now that IS a reflection on battery health.

 

[dtbaker61]

I get that, but if a battery has a state of charge of 90% today, and 50% two days from now that IS a reflection on battery health.

Not really. That is just the state of charge. What matters is whether or not the battery can recover, and how much energy is accessible from Full voltage at the end of charge until voltage drops to the point it either calls for a charge from the high voltage battery or you drive it around. That is the capacity. That changes over time. That is the actual health.


Let me rephrase. A brand new battery of this size has a capacity of 35 amp hours. That means it can support a current draw of 35 amps for an hour. At the top of charge it has a float voltage of 13.8, which settles down to about 12.8 with no load. As soon as you apply a load and consume energy the voltage will start dropping. A brand new battery can support a load for longer than an old battery until it hits that bottom voltage and needs to be charged. That is capacity health. The upper and lower voltages are still the same, it is just a matter of how long it can support the load and whether or not it takes a charge and holds a charge

 

[dtbaker61]

I get that, but if a battery has a state of charge of 90% today, and 50% two days from now that IS a reflection on battery health.

Not really. It is just an indication that the vehicle woke up and was on for a few minutes and went back to sleep. These batteries are so small it takes quite a bit of % each time they wake up before they go back to sleep. If the SOC regularly ends up below 50 or 60%, after one 10 minute shutdown and normal night's sleep then that might indicate reduced overall capacity, but it is not a for sure indicator since you don't really have any idea what might have used the energy.

State of charge is not a good indicator of Health unless you do an actual output energy Measurement with a known load for a known amount of time.

There have been LOTS of 2021s reporting sudden death of the 12v without much warning. Average life seems to be 36-40 months.

Mine died in the middle of an errand trip around town with zero warning, and locked the doors behind me!

 

[Flyer_313]

as VGK suggest above, just keep an eye on the 12v status on the ford.com page. I don't see preemptively replacing a battery that's giving no indications of failing. There's actually a thread on that subject. I check mine several times a week out of curiosity, it's almost always above 80% and usually 85-95%.

Ford.com Then sign in>account>(yourname)account. The charge level is actually your 12v charge level.

I read your post and after watching the charge value it appears to be the charge is the main battery not the 12 volt battery.

 

[Snakebitten]

I read your post and after watching the charge value it appears to be the charge is the main battery not the 12 volt battery.

True.
But that's a recent change made by Ford to correct their website error. Unfortunately, according to some.

 

[Jerrytball]

Ford.com Then sign in>account>(yourname)account. The charge level is actually your 12v charge level.

Actually, and I verified this recently they no longer show the 12 V battery charge on the website. That’s why I use my ODB two scanner.

 

[dtbaker61]

Actually, and I verified this recently they no longer show the 12 V battery charge on the website. That’s why I use my ODB two scanner.

with a wireless BT ODB2 you can't see the voltage when the MME is 'sleeping' because the BT wakes the car up. This is why I picked battery cables that have a built-in voltmeter for my export cables.... sometimes I leave the hood up in the garage, and it's kind interesting to see how fast the 12v voltage drops when the car is OFF, and then drops again if your BT 'wakes it up' on a walk by.

This is why I turn BT off on my phone when I am home... I am in and out of garage many times a day.

 

[zvez]

I read your post and after watching the charge value it appears to be the charge is the main battery not the 12 volt battery.

yes ford "fixed" the ford.com 12v status about two weeks ago, no more 12 v without getting car scanner and obd reader.

 

[Jerrytball]

with a wireless BT ODB2 you can't see the voltage when the MME is 'sleeping' because the BT wakes the car up. This is why I picked battery cables that have a built-in voltmeter for my export cables.... sometimes I leave the hood up in the garage, and it's kind interesting to see how fast the 12v voltage drops when the car is OFF, and then drops again if your BT 'wakes it up' on a walk by.

This is why I turn BT off on my phone when I am home... I am in and out of garage many times a day.

I am getting a 5 foot extendable ODB two port and I’m gonna keep it close to the center consul when I’m driving I just plug in my little device and it shows me what my current state of health is on the 12 V battery so as far as I’m concerned, if it’s 92% while I’m driving, it should be fine overnight so I don’t look at it when I turn it on anyways if it dies overnight, that’s something going on

 

[ocdxfv]

So for the last 2 days I charged my battery by leaving the car on in my garage for several hours during the day. The first day I charged it to 85% and over night it discharged itself to 79%. That looks good but the second day (yesterday) after a relatively short drive the car charged to 82% and in the morning it was down to 67%. In both cases there are no external devices plugged In including the OB2 device which I found drains the battery and lights are set to off. My key is not within BT range at night.

My battery is now around 39 months old (Since build date) and I am trying to determine whether or not to proactively replace it. Do these overnight discharge amounts indicate a weakening battery or do I need more tests? I live in SoCal. Thanks

Curious if you ever changed out your 12v battery. I just did mine this past week. I'm also in So Cal. '21 Select with build date of 11/20 (coming up on 4 years old!)

 

[FordMachEGo]

Curious if you ever changed out your 12v battery. I just did mine this past week. I'm also in So Cal. '21 Select with build date of 11/20 (coming up on 4 years old!)

Yes I did. I did not want to risk it. Went with mobile service from Ford dealer for $280 installed.

 

[dtbaker61]

I am getting a 5 foot extendable ODB two port and I’m gonna keep it close to the center consul when I’m driving I just plug in my little device and it shows me what my current state of health is on the 12 V battery so as far as I’m concerned, if it’s 92% while I’m driving, it should be fine overnight so I don’t look at it when I turn it on anyways if it dies overnight, that’s something going on

when you are driving, the 12v will show you the dc-dc voltage , probably right around 13.5 almost all the time, this is unrelated to 12v battery 'state of health'. Getting an ODB2 for this purpose won't tell you what you are looking for.

what people are concerned about is when you are NOT driving, and either waking up your MME by walking by, or draining the 12v during a long OTA download, and the 12v fails to get a charge from the HV.

or, after about 3 years, when 12v capacity is reduced from aging, and the 'usual' 3-5 ah it takes to go to sleep wipes out the battery and it doesn't have enough oumph to run the computer.

 

[Jerrytball]

when you are driving, the 12v will show you the dc-dc voltage , probably right around 13.5 almost all the time, this is unrelated to 12v battery 'state of health'. Getting an ODB2 for this purpose won't tell you what you are looking for.

what people are concerned about is when you are NOT driving, and either waking up your MME by walking by, or draining the 12v during a long OTA download, and the 12v fails to get a charge from the HV.

or, after about 3 years, when 12v capacity is reduced from aging, and the 'usual' 3-5 ah it takes to go to sleep wipes out the battery and it doesn't have enough oumph to run the computer.

Car on not started % 91 seems good …no? This is first thing morning?

 

[dtbaker61]

Car on not started % 91 seems good …no? This is first thing morning?

there is no display of 12v 'health' anywhere.

you can display voltage, but that doesn't tell you anything about capacity on the 12v battery. voltage anywhere between 12.4-14.5v on the 12v is to be expected regardless of health.

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