AGM battery reliability

[Bsthroop]

We've gone around the full discussion again but here is the reason the BMS is killing the batteries. From the link @Dereku posted above.

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[Muffin1]

Being that you performed the BMS reset without changing the battery, I am curious of your outcome and if it fixes the issues you were having.
I am trying to determine if a simple reset of the BMS system will fix the issues owners are having vs replacing the battery and performing the BMS reset (Together)

I will definitely update next week and after reading the other post's about AGM's I'm thinking about going back into Forscan and move up the charge % from 75 to 90, at this point if the battery has been damaged from being short charged over the last couple years i can't imagine any more harm, and if not then maybe the 100% can Defibrillate it back and it's a no cost experiment.

 

[Dr3wDrop]

Quick update. Ford Tech couldn’t reproduce the door locks going haywire or the sonar noise. I asked if they load tested the battery like I asked and they said no. Apparently, they are going to stress test the battery now for warranty which takes 4-6 hours? Guess I gotta wait until tomorrow.

well no luck on my end. They called me back and said the battery tested fine and there was nothing they can do. What was really strange is he said the battery is rated at 800 cold cranking amps and it tested at over 1000. His exact words were it’s a “really good battery”.

 

[Blue Streak]

Wow what a long read. I also use a battery maintainer. My 19 is 3 1/2 yrs old with 35000 plus miles. No battery issues to date. Since I do not use ASS & I use a maintainer I can assume I will not have an early indication on my battery condition. ?

 

[seanellaz]

Well It looks like the AGM battery in my Ranger was designed to expire the same day as the truck warranty.
It will still start but it has taken to going to battery saver mode after 24hours parked in a heated garage.
It apparently will no longer hold a full charge and will drop to 12.0V in less than 24hrs.
Now I understand "keep alive" draw, but that should not be this bad. the battery is just getting weaker.
Am I missing something? This is my first AGM Battery.
Does anyone know a good reason not to switch to a flooded lead acid battery?
I have never gotten less than 6 years on an OEM battery in a new car,
then I read that life expectancy on an AGM is 3-1/2 to 4 years.
The price is likely 2-3 times that of a flooded battery with half the life cycle.
I did read from a battery maker that an AGM battery should be manually charged once a month to get maximum life from it.
What say all y'all?

Plug it into a trickle charger / maintainer. You can get one for under $20 with leads having rings to permanently attach to battery and cable you can plug / unplug quickly. Example: https://www.amazon.com/Automatic-Ma...ttery+maintainer+charger,aps,146&sr=8-50&th=1 Do this before it is dead or low charged. The battery will last a very long time, and the truck will not go into sleep mode. BTW - I have found no need to permanently attach the charger upstream from the BMS sensor. I attached both leads directly to the actual battery. In my case, the negative lead is not connected to ground away from the battery. Every time I start the vehicle, the BMS is smart enough to actually read the actual state of charge / discharge of the battery. I do not care that the BMS does not "know" that the battery is being trickle charged / maintained @ the battery terminal posts.
If you wait until the battery is dead or nearly dead, you will have to use a dumb charger, one that does not 1st look to see if the battery is dead before charging it. Many "smart" chargers will refuse to initiate charge on a dead battery.

 

[Langwilliams]

Being that you performed the BMS reset without changing the battery, I am curious of your outcome and if it fixes the issues you were having.

I did a reset when my truck started shutting the radio off just a few minutes after parking an shutting the 12v charger off right away. The radio an charger worked longer for about a month then the quick shut off returned. I generally get to work early an listen to the radio for a bid before starting so it was noticeable.

 

[HowIconic!]

Howicionic:

I am in process of putting together a detailed report on the BMS,
Now that the battery is fully charged, per the manuals and documentation I have found it takes 6 to 8 hours (At rest & untouched) time for the BMS system to refresh, once it sees a new refreshed SOC above 11.3 volts, the A/Start should now enable.
Please post your results after next drive, to see if this is a fix (recharge)
I am trying to determine if all the issues owners are having with A/Start (Charging) issues is:

A. Bad Battery, once replaced by dealer - If they are following procedures - Perform BMS Reset
and then owners report - Fixing the Problem

B. Which one of the above is actually fixing it? The Battery? - The BMS Reset? - or Both?

C. Is the Bad Battery being caused by the Aging Battery Charging Algorithm?
or just a simple battery that has failed to hold a charge?

Ok. Supposedly the dealership put it on their BIG charger for several hours. On the way home it drove fine. ASS still inop. Drove it aday or two later - still no stop/start. Drove it today, air conditioner off. Came to a light - gray circle came on engine still running.

 

[KJRR]

I am in process of putting together a detailed report on the BMS,
Now that the battery is fully charged, per the manuals and documentation I have found it takes 6 to 8 hours (At rest & untouched) time for the BMS system to refresh, once it sees a new refreshed SOC above 11.3 volts, the A/Start should now enable.

Some thoughts on the BMS and charging AGM batteries...
I'm using the info provided here for my thoughts - How To Charge A Agm Battery?

If we assume a full charge at rest on an AGM battery is 13V, and the BMS is limiting the charge to 70%, the battery will only be charged to 9.1V (70% of 13v). That is below the level you stated the BMS is looking for.
If we juggle the math, and assume 11.3V is the 70% state, we are looking at about 16.2V as full charge at rest on the AGM battery. I don't think the AGM chargers are charging to that level.
This can be verified if we measure the voltage at the battery while the vehicle is running.

My thought is the 70% is the max charging rate, (maybe amps or watts, not sure) that the BMS limits the alternator to putting out. This would go along with the theory that slow charging (less than 10A) is better for AGM batteries than fast charging due to the heat.

I haven't looked into the BMS in depth but knowing that it is connected to the negative side of the battery, I'm thinking it is measuring current rather than voltage. This would also be why when you charge the battery, the negative lead of the charger is connected to a grounding point rather than the negative terminal of the battery. This allows the BMS to measure the current.

I've had my battery replaced after 3 yrs and also the BMS module because the dealer said it wasn't charging properly. I don't plan on changing the 70% until I understand what that change will affect.
I guess we could measure the charging voltage at 70% and at 90% and see if there is a voltage difference at the battery. I don't have a ammeter to check the amperage going to the battery at 70% and 90% but perhaps someone else does.

Thanks for digging into this and sharing the results.

 

[airline tech]

I almost have my Tutorial complete, but you are missing what SOC is on a battery, and the system will charge to 100%, I will reveal what the 70% thing is all about and explain it in detail and also explain why that 70% is causing issues.

Plus, without backtracking did you actually see that number in Forscan , I have conflicting info on that number. Most members report 70% and my truck shows 75%

More to come, hopefully within a week, I want to do some more on truck tests.

 

[airline tech]

This right here is why it confuses people, this charging cycle is for Deep Cycle AGM batteries, not Starting Battery -AGM.
It is referencing - a external battery charge voltage. Very conflicting and confusing.
If you scroll down to the bottom of that guide - It states -Deep Cycle
I am putting together a detailed thread on the BMS system, I have more testing to complete

I will admit I was wrong on this; the OP is correct about the AGM battery; I have a complete tutorial on this coming soon, this system is all over the place on how it works, but I have it figured out for the most part.
Sorry and more to come

 

[SigOris]

Best thing to do is put it on a maintainer and keep it fully charged up. I never messed with Forscan but you could and set it to 90% like Trig has done. Other than that just drive it and have fun and dear God don't smell your oil!

And you missed your plug for one of these sold exclusively thru you ???

 

[SigOris]

Sorry I no longer feel this to be a productive discussion, I give you evidence why many people on this board believe that even an AGM battery is best maintained at 100% capacity via use of battery maintainers and you bring up other objections, what I attempted in this thread is provide logical explanations how the bms interacts with a traditional vehicle charging system and a hypothesis why the soc of charge is set at 70% and why that ties to the battery failures posters have experienced, you manage your battery the way you choose and I'll will manage mine, thus far my oem battery is doing just fine at a 100% charge rate.
Just to add the history of auto mfg there are numerous errors, miscaclulations, oversights etc as it pertains to design and engineering, that's one of the reasons we have recalls, redesigns, premature failures and so on, engineers don't always get it right and some decisions are made in the pursuit of chasing mpg efficiency that can and have had negative consequences.

I beg to differ, us engineer’s always get it right the first

 

[airline tech]

Another Update:

My Bat Target SOC compare is still in-work, I have completed the 80% test, and have it set to 90% now, will monitor that and then revisit the 75% (factory setting) to get accurate test numbers.

I did finally get into FORscan today and play with its Live Data feature, I can get it to display all parameters (PIDS) relating to the Battery and Charging system except the one that most interested owners that viewed the - Ford - F-150 video (BMS). Neither my Autel Scanner ($1500) or FORscan will display this PID (Bat_ST_CHRG) - Vehicle Battery - State of Charge.
So, it boils down to the Ranger BCM is not programed to display this parameter, at least that I can find.
So, you have to rely on the Bat Voltage and then you the chart (SOC) to see what it is. I plan on taking another look after my (90%) voltage compare is complete, while I'm hooked up to see if I can find that exact PID.

Stay Tuned

 

[dtech]

I beg to differ, us engineer’s always get it right the first

I was one of them once, then switched to sales and marketing where it was sink or swindle, lie and cheat , survival of the slimyiest.

 

[Big Blue]

I was one of them once, then switched to sales and marketing where it was sink or swindle, lie and cheat , survival of the slimyiest.

So, you went to the Dark Side.

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