AGM battery reliability

[dtech]

It's a lead acid battery, 100% charge rule applies. Charging requirements differ slightly from wet cell batts, bms adds some worthwhile features but cars did ok for decades without it and used wet cell batteries, load shedding has been around way before bms became a thing

Sponsored

 

[Langwilliams]

It will be 3 years since I bought my truck Dec 30th....right now when I shut the key off the 12v shuts off right away an the radio about a minute or 2 later. When it was new both went like 15 minutes so I assume the battery is on it's way out. I've been afraid to mess with the charge % but I'm tempted to take it up to 80% just to see if this changes the key off charging. If it does I wonder if I might squeeze a few more months out of it? I tuned my truck about 6 months after buying it an that removed the ASS feature. Rarely does my truck go a day without being driven.

The AGM batteries in Harley's have gone 7 years for me. I put them on a tender when stored or when not riding daily. I only have one charger so it gets rotated between 3 garden tractors an the bike.

 

[maxbottomtime]

Funny, i had an appointment at the dealer today for my battery failing.

Specifically, over the last week the ASS has completely stopped working, and 4-5 times I'd drive for 45min (highway speeds), and as soon as i get out and lock the car i get the ford app notification that connected services have been disabled to preserve the battery. Pretty clearly the battery is not holding a charge, alternator is good. At no point did the car sit for more than a day.

I get in, the dealer takes 40 minutes or so before pulling the truck around to the garage, an hour fifteen before they call me back. Battery tested fine. Well, they hooked it up to the first charger and that didn't work but the second charger/tester got it up, and it tested at 12.6volts.

Me: "okay, why is the remote start disabled immediately after driving for extended periods?"
Tech: "It's to preserve the battery. it isn't giving a code. that's normal"
me: "Autostart stop hasn't run in a week."
Tech: "That's normal don't worry about it"
Me: "what was the voltage before you charged it? I drove here for 30 minutes, and it ran for 2 hours last night"
Tech: "12.1volts. but anything over 12 volts is good"

Overall, tech was argumentative, dismissive, said "well it tests good", etc. The truck is 17 months old.



I had to talk to their service manager, and reference another incident in which i left poor feedback (recall for headrests where they spent months giving me the runaround and hadn't even requested the replacement parts).

Service manager sternly told the tech to replace it. I'm 50/50 whether they actually did anything. the stupid cover on the battery prevents me from seeing the date. Will pull when the windchill isn't -40. No service record or receipt.

Real kicker - they sent me a text after with "additional service suggested" I click the link: no description, no text, just a photo of my 12v selector switch for my winch. Okay? A switch that has been in the off position, clearly has no faults (as the 2ga wire certainly cause some visible damage, and also the positive has wire protector over it). Petty.

 

[Bsthroop]

Using Forscan I reset my max charge on the battery to 90%. Since then I have stopped having issues of "deep sleep", slow screens, non-responding proximity sensors, etc. occur. It baffles me that Ford set the charge level so low on these batteries. My thought on using a battery maintainer is that you would be charging the battery to full from a source external to the electrical system in the truck, so there will be a conflict between the BMS and what the system thinks the battery charge level is. Again, just my thought on this, I am not an electrical engineer..

You just need to hook up the charger ground outside the BMS sensor on the battery ground terminal to ensure the system tracks the battery's charge level. Best way is to connect the charger negative a chassis ground.

 

[Big Blue]

It's a lead acid battery, 100% charge rule applies. Charging requirements differ slightly from wet cell batts, bms adds some worthwhile features but cars did ok for decades without it and used wet cell batteries, load shedding has been around way before bms became a thing

I agree with you to a point. The 100% state of charge is not the issue
I have no idea why Ford sets it at 70% or 75%. What is an issue is continuing to charge at 14+ volts once the battery is at 100% SoC. AGM batteries don't like that and develope sulfite dendrels in the glass mats separating the plates. Hense, the need to run a desulfinate cycle on your smart charges every once in a while.

So I would would not disable the BMS by disconnecting the SoC sensor. But, go into Forscan and up the SoC setting to maybe 95%. That and take your ranger out for long rides once in awhile, it likes the exercise.

Our trucks have a lot of always on systems. AGM batteries are better at low constant draws than wet cells. They also, as you said, have different charging requirements. So, if you like all the features you need to understand the batteries needs. Drive it or put it on a tender, if is going to sit awhile.

This my take from reading all the battery threads on here. I am by no means a battery expert, so if I'm way off let me know.

 

[dtech]

I agree with you to a point. The 100% state of charge is not the issue
I have no idea why Ford sets it at 70% or 75%. What is an issue is continuing to charge at 14+ volts once the battery is at 100% SoC. AGM batteries don't like that and develope sulfite dendrels in the glass mats separating the plates. Hense, the need to run a desulfinate cycle on your smart charges every once in a while.

So I would would not disable the BMS by disconnecting the SoC sensor. But, go into Forscan and up the SoC setting to maybe 95%. That and take your ranger out for long rides once in awhile, it likes the exercise.

Our trucks have a lot of always on systems. AGM batteries are better at low constant draws than wet cells. They also, as you said, have different charging requirements. So, if you like all the features you need to understand the batteries needs. Drive it or put it on a tender, if is going to sit awhile.

This my take from reading all the battery threads on here. I am by no means a battery expert, so if I'm way off let me know.

Agree 100% with what you state and I think someone was correct that the 70% soc is mostly for mpg , lead acid batts charge less efficiently as they approach 100%, agm more than wet cell, that internal resistance produces heat and too much heat can degrade, hence chargers with higher output have agm setting that lowers charge voltage. I don't use forscan but reason that 14v charge is less harmful over time to battery life than continual 70% soc. I live in a relatively cool area temps rarely exceed 90 F in a hotter climate would avoid the 100% soc, in my mind the ideal solution would be to decrease the alternator charge voltage as the soc increases towards 100% thus controlling the internal battery temps.

 

[dtech]

just to expound on what I wrote - I don't use ASS, if one does that's an entirely different scenario, say your daily commute is in constant stop and go traffic, that will require both battery power and engine power to run the alternator and that will impact fuel efficiency, unknown if to the degree that enough owners would bitch and force Ford to retest the epa numbers, easier to just limit the soc and an agm will handle those ass cycles effectively but ultimately that 70% soc will likely accelerate the sulfation of the battery and shorten it's life. Since I don't use ass nor have bothered with forscan I'll just put a wet cell in there when the agm is done.
So almost counter intuitive to utilize ASS to get higher epa nos, but loading the alternator to get the batt back to 100% would diminish fuel efficiency so lowering the soc 70% would seem to be the reason engineers choose that % . And it would appear that 70% soc is costing Ford in warranty $$ .

 

[Cabose-1]

Agree with big blue. Can not compare new agm batteries with old batteries, or new and old cars. Old cars did not have infotainment screens modems, keyless entry, apps to turn on car, delayed lighting, app tracking etc etc

Old cars had on star, radio and alarms.

Like old blue said, no battery expert or scientist, just know 2 big different requirements. Same but different.

And agm batteries, well, not all created equal. Ifbdue tobuser habits or battery itself. I don't know

 

[D Fresh]

Yes, Baby Step, this is what is frustrating, one site says AGM 100% and another says 80% and then our ranger has 70% (via FORscan) visible.
What is the correct info? it's all over the place on finding info (documented) and verified correct
even the AGM SOC charts jump all over the place, what I can tell is that the old school 12.6 is now 13.0 volts with AGM

I fugured as much. Way back in the day I went to school for Avionics. I can tell by your posts that you are a true technician, not a just a "mechanic." The documentation game you've brought to the forum is impressive.

I'm good with guessing and cranking her up. But I'm watching for your findings.

Funny, i had an appointment at the dealer today for my battery failing.

Specifically, over the last week the ASS has completely stopped working, and 4-5 times I'd drive for 45min (highway speeds), and as soon as i get out and lock the car i get the ford app notification that connected services have been disabled to preserve the battery. Pretty clearly the battery is not holding a charge, alternator is good. At no point did the car sit for more than a day.

I get in, the dealer takes 40 minutes or so before pulling the truck around to the garage, an hour fifteen before they call me back. Battery tested fine. Well, they hooked it up to the first charger and that didn't work but the second charger/tester got it up, and it tested at 12.6volts.

Me: "okay, why is the remote start disabled immediately after driving for extended periods?"
Tech: "It's to preserve the battery. it isn't giving a code. that's normal"
me: "Autostart stop hasn't run in a week."
Tech: "That's normal don't worry about it"
Me: "what was the voltage before you charged it? I drove here for 30 minutes, and it ran for 2 hours last night"
Tech: "12.1volts. but anything over 12 volts is good"

Overall, tech was argumentative, dismissive, said "well it tests good", etc. The truck is 17 months old.



I had to talk to their service manager, and reference another incident in which i left poor feedback (recall for headrests where they spent months giving me the runaround and hadn't even requested the replacement parts).

Service manager sternly told the tech to replace it. I'm 50/50 whether they actually did anything. the stupid cover on the battery prevents me from seeing the date. Will pull when the windchill isn't -40. No service record or receipt.

Real kicker - they sent me a text after with "additional service suggested" I click the link: no description, no text, just a photo of my 12v selector switch for my winch. Okay? A switch that has been in the off position, clearly has no faults (as the 2ga wire certainly cause some visible damage, and also the positive has wire protector over it). Petty.

Not to take away from your point. But extreme cold is one of the conditions that will keep the ASS from functioning. You can check what is keeping ASS from functioning from the "economy's screen.

 

[D Fresh]

I agree with you to a point. The 100% state of charge is not the issue
I have no idea why Ford sets it at 70% or 75%. What is an issue is continuing to charge at 14+ volts once the battery is at 100% SoC. AGM batteries don't like that and develope sulfite dendrels in the glass mats separating the plates. Hense, the need to run a desulfinate cycle on your smart charges every once in a while.

So I would would not disable the BMS by disconnecting the SoC sensor. But, go into Forscan and up the SoC setting to maybe 95%. That and take your ranger out for long rides once in awhile, it likes the exercise.

Our trucks have a lot of always on systems. AGM batteries are better at low constant draws than wet cells. They also, as you said, have different charging requirements. So, if you like all the features you need to understand the batteries needs. Drive it or put it on a tender, if is going to sit awhile.

This my take from reading all the battery threads on here. I am by no means a battery expert, so if I'm way off let me know.

Agreed.

I'm at 95% via ForScan.

 

[maxbottomtime]

I fugured as much. Way back in the day I went to school for Avionics. I can tell by your posts that you are a true technician, not a just a "mechanic." The documentation game you've brought to the forum is impressive.

I'm good with guessing and cranking her up. But I'm watching for your findings.




Not to take away from your point. But extreme cold is one of the conditions that will keep the ASS from functioning. You can check what is keeping ASS from functioning from the "economy's screen.

Absolutely. It was doing this at 40 degrees which generally I wouldn’t think is extreme.

 

[D Fresh]

Absolutely. It was doing this at 40 degrees which generally I wouldn’t think is extreme.

Gotcha. Just wanted to make sure you were aware.

 

[AzScorpion]

It will be 3 years since I bought my truck Dec 30th....right now when I shut the key off the 12v shuts off right away an the radio about a minute or 2 later. When it was new both went like 15 minutes so I assume the battery is on it's way out. I've been afraid to mess with the charge % but I'm tempted to take it up to 80% just to see if this changes the key off charging. If it does I wonder if I might squeeze a few more months out of it? I tuned my truck about 6 months after buying it an that removed the ASS feature. Rarely does my truck go a day without being driven.

The AGM batteries in Harley's have gone 7 years for me. I put them on a tender when stored or when not riding daily. I only have one charger so it gets rotated between 3 garden tractors an the bike.

If you have time and can get an appointment next week bring it to the dealer before the 30th. If the battery is going dead might as well get it covered under warranty.

 

[Apples]

A few folks here need to spend some time here: https://batteryuniversity.com/

Even on the first page there are two errors about maintaining an AGM battery.

 

[D Fresh]

A few folks here need to spend some time here: https://batteryuniversity.com/

Even on the first page there are two errors about maintaining an AGM battery.

I'm not reading all of that.

I read the AGM section, didn't notice anything contrary to what we're saying here.

Care to enlighten us beyond a vague link?

Sponsored