Charging once a week even though you don’t need to…

[DugthePug Dad]

I find myself charging every 7-10 days and I don’t really need to.

I don’t drive much but I feel better plugging my car in every so often to keep things fresh.

Most of my charging is from the mid to high 60’s% to 90%.

I think it keeps the 12V fresh.

Am I wrong about the 12V ?

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[AKgrampy]

I do not think charging keeps the 12V fresh. Driving is what works best. I do think, and hopefully the knowledgeable people will chime in, that if the 12V system is low it will be maintained while charging. The key is the HVDC system in the car maintains the LVDC system - charging does not have an impact per see. Always learning so I will see what the answer is!

 

[Mach-Lee]

I find myself charging every 7-10 days and I don’t really need to.

I don’t drive much but I feel better plugging my car in every so often to keep things fresh.

Most of my charging is from the mid to high 60’s% to 90%.

I think it keeps the 12V fresh.

Am I wrong about the 12V ?

Yes, that’s probably a good idea. Avoid deep depth of discharge.

 

[Teslaeata]

I find myself charging every 7-10 days and I don’t really need to.

I don’t drive much but I feel better plugging my car in every so often to keep things fresh.

Most of my charging is from the mid to high 60’s% to 90%.

I think it keeps the 12V fresh.

Am I wrong about the 12V ?

The car has a perfectly good 12V battery management system so you don’t have to worry or overthink things.

So long as HV battery is over 15% charged the DC/DC 12V charger will do the business.

If 12V battery voltage drops to a percentage state of charge (can’t remember what it is ATM) will trigger a charge within 48 hours and if 12V battery drops below that to another lower threshold which I also can’t remember ATM and we don’t need to concern ourselves with will trigger charging immediately whether car is plugged in or not.

So, don’t worry and just enjoy your car.

 

[Teslaeata]

Yes, that’s probably a good idea. Avoid deep depth of discharge.

You won’t get to a “deep depth of [12V] discharge” the car won’t allow it whether you’re driving or parked, plugged in or not so long as HV battery is more than 15% charged ?

 

[AliRafiee]

No point in letting it go down.
The battery has a lifespan based on X number of charge cycles. A cycle is from 0 to 100%.
If you charge 10 times from 80 to 90%, that’s one cycle.
Charge when you want and don’t worry about it.
I personally don’t like getting below 50-60% because I might need to go somewhere and might need the range.

 

[Mach-Lee]

You won’t get to a “deep depth of [12V] discharge” the car won’t allow it whether you’re driving or parked, plugged in or not so long as HV battery is more than 15% charged ?

Yes, because the recharge threshold is fairly deep at only 40% SoC (60% DoD). If you drive/charge the car regularly and keep the 12V above 70% SoC (30% DoD), the battery will last twice as long than if you rely on the 40% SoC automatic failsafe recharge program:

Lead acid batteries need to stay at close to full charge to maintain performance. When they get low, sulfation builds up on the plates which blocks the active material. This sulfation hardens with time, so the longer the battery is at a low state of charge (below about 60%) the more capacity loss it will have. This is why you want to recharge your lead acid batteries right away rather than letting them sit low.

Capacity loss from chronic undercharging combined with cold temps is a recipe for battery failure.

It’s also a well-known fact among Ford technicians that the 12V BMS is designed for typical use only, and is not optimized for short trips or infrequent use. Vehicles that are driven only a couple miles at a time, or that are only driven once or twice a week tend to experience more 12V failures because the battery cannot spend enough time charging to clear out all the sulfation.

The Mach-E BMS is mostly copied from ICE vehicles and is not optimized for being an EV. It should wake up and charge the 12V battery for a few minutes every 24 hours, and the automatic recharge threshold should be set much higher than it is. Ford is still learning about battery management in EVs and has been applying old-school “no drain” thinking to their methods.

People that drive and charge their car regularly do not need to worry about their 12V battery. But people that fall into the short/infrequent use category should spend a little time thinking about 12V maintenance as this OP has, that would be prudent. A 60% to 90% charge will last at least several hours, which should be enough for the 12V battery to get mostly charged up. 12V management can be as simple as this (or leaving the car on in the garage once a week), and doesn’t have to involve popping frunk covers and external battery maintainers. But it’s clear from all the 12V issues reported on the forums that the stock Ford charging system management is not robust enough for everyone to just “forget about it.”

 

[DugthePug Dad]

But it’s clear from all the 12V issues reported on the forums that the stock Ford charging system management is not robust enough for everyone to just “forget about it.”
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This is why I started this thread.

I just don't drive daily in retirement. Most my driving is to the grocery store or the local sports bar or restaurant etc.

I have had my beautiful MME since the 4th of July and I have not put 1,500 miles on it yet.

Thank you for the information.

 

[Auto Motive]

I do not think charging keeps the 12V fresh. Driving is what works best. I do think, and hopefully the knowledgeable people will chime in, that if the 12V system is low it will be maintained while charging. The key is the HVDC system in the car maintains the LVDC system - charging does not have an impact per see. Always learning so I will see what the answer is!

Every two weeks our GTPE plugged in didnt work for as I got either plug car in notice or a 12v default. Once every 7 days does the trick 60pct to 80pct. Our 2023 tesla y has a 16v lithium battery that keeps ev good for a month or longer-term .

 

[sukhoi_584th]

No point in letting it go down.
The battery has a lifespan based on X number of charge cycles. A cycle is from 0 to 100%.
If you charge 10 times from 80 to 90%, that’s one cycle.
Charge when you want and don’t worry about it.
I personally don’t like getting below 50-60% because I might need to go somewhere and might need the range.

Pretty much everything here is wrong or unintentionally correct

 

[DugthePug Dad]

Pretty much everything here is wrong or unintentionally correct

Can you expand your response further ?

 

[sukhoi_584th]

Can you expand your response further ?

I was only referring to that quote. That's not how charge cycles are calculated.

For your use case you'd be better off staying between 50-80% than 60-90%. Lowest degradation is roughly in the 35-80% range, though this is skewed a bit by Ford programming in some hidden buffer. There are different degradation mechanisms but on the high end it's literal expansion and cracking due to packing the last of the Li ions into the least receptive lattice locations. That's all for the HV battery, not the 12 V. Thread info about the 12 V is correct.

 

[AliRafiee]

I was only referring to that quote. That's not how charge cycles are calculated.

For your use case you'd be better off staying between 50-80% than 60-90%. Lowest degradation is roughly in the 35-80% range, though this is skewed a bit by Ford programming in some hidden buffer. There are different degradation mechanisms but on the high end it's literal expansion and cracking due to packing the last of the Li ions into the least receptive lattice locations. That's all for the HV battery, not the 12 V. Thread info about the 12 V is correct.

Please let us know how charge cycle works.

Don’t forget to include some sources.
https://en.wikipedia.org/wiki/Charge_cycle

https://au.renogy.com/blog/everything-you-need-to-know-about-lithium-battery-charging-cycles/

Also my point is that having the car plugged in maintains the 12v battery. No reason to guess and make life harder.

I have cars and motorcycles that don’t get ridden very often. They are always on a battery tender. My EVs in the past 6 years have been plugged in almost every day.

 

[sukhoi_584th]

Please let us know how charge cycle works.

Don’t forget to include some sources.
https://en.wikipedia.org/wiki/Charge_cycle

https://au.renogy.com/blog/everything-you-need-to-know-about-lithium-battery-charging-cycles/

Also my point is that having the car plugged in maintains the 12v battery. No reason to guess and make life harder.

I have cars and motorcycles that don’t get ridden very often. They are always on a battery tender. My EVs in the past 6 years have been plugged in almost every day.

I don't know the specs off the top of my head and don't feel like spending more time on this. The "charge cycle" ratings are based on a defined amount of degradation over a specific charge/discharge range. Your comment that you can discharge 10% 10x and it's equal to one charge cycle is not correct.

 

[AliRafiee]

I don't know the specs off the top of my head and don't feel like spending more time on this. The "charge cycle" ratings are based on a defined amount of degradation over a specific charge/discharge range. Your comment that you can discharge 10% 10x and it's equal to one charge cycle is not correct.

Very nice. Thank you for the extremely useless comment and waste of everyone’s time.

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