14.4 volts, with temperature compensation to reduce that voltage to 13.9 volts during higher temps.

My personal truck is now a quarter of a century old, so there is no BMS, and no SOC to have to interpret the sense of.

I selected the charging voltage by choosing an alternator with a built in voltage regulator having the characteristics described in the first sentence above.

I actually wanted a different alternator, but because the internal voltage regulation was higher, at 14.8 volts, I did not want to run the risk of having that high of charging voltage.

If I lived in a really shivering cold climate, then I'd be more comfortable with voltage regulated at 14.8, but the consequences of over charging are irreversible in VRLA sealed AGM batteries.

Sealed batteries remain sealed, until the pressure inside the battery exceeds the pressure outside the battery by about 1.5 psig. That's when the valve regulation comes into play. It is a one way valve... relieving pressure. During that moment (or repeated moments) of pressure relief, the one way valve releases what was causing that pressure... a build up of free gas that was not absorbable by the mats because the gas was generated at too rapid of a rate to be absorbed, from too high of a charging voltage, where voltage is the electrical pressure moving the electrons causing these chemical reactions.

Once the pressure sensitive valve opens to release the build up of gas, the constituents of the gas released are gone forever out of the sealed battery. Those lost constituents are the building blocks of the battery's electrolyte.

Oxygen is one of the gasses released, from the positive plate. And hydrogen is another gas released, from the negative plate. If the pressure wasn't greater than 1.5 psig in the battery, and the valve stayed closed, then the oxygen released from the positive plates would recombine with the hydrogen released from the negative plates, (hence "recombinant") and form H₂O, which of course is water... the electrolyte elixir that we can't put back into an AGM battery because it is sealed.

So the last thing we want to do is gas the elements of the electrolyte elixir out, from applying to much electrical pressure (voltage) that causes chemical reactions to take place faster than the glass mats between the positive and negative plates can absorb.

That's why setting up the right SOC in these fancy pants computer controlled trucks is kind of a big deal when utilizing AGM batteries, to any extent that the truck's outstanding designs of segmented conductor alternators have the ability to generate and maintain higher system voltages despite the increased electrical loads the vehicle has overall.

 

Sitting for a week at a time without use might be fine, IF your drive time is lengthy when you do drive. My wife uses her '20 Edge (with AGM) that way, and if she's only running a weekly round trip of 30 minutes, the Edge goes into battery save mode about once per month. If her drives are an hour or more, once a week, it never goes into battery save mode. If it's driven that same 30 minute round trip daily, it doesn't go into battery save mode.

 

100% agree and thank you for the quick and detailed response.

Figuring out the optimum SOC via monitoring the charging voltage may be the only way we, as end users, will be able to approximate what the Ideal SOC parameter actually is for the algorithm that the Ford engineers developed.


Thanks again for all the info Y2KW57,

Bob

 

What about a older truck such as mine? I have a 99 sd f350 7.3 and am thinking about replacing bad motorcraft batteries with some walmart platinum agms, I have a small parasitic draw due to alarm system that uses some power for GPS location as well as anywhere remote start capability using cell service. I don't drive it alot so it sits sometimes a week or 2 without driving it and my batteries were getting run down, To combat the small draw i have a Deltran Battery Tender Junior .750mA maintainer that i keep plugged into the truck 24/7 when i am not driving it to keep the batteries charged. My question is i guess Will this cause premature loss of life of my batteries flooded or agm if my maintainer is kicking on and off topping off my batteries all the time?

Someone told me this is bad for them and probably why my flooded motorcrafts keep dying every few years but i said how is it different then what alternator does? If the maintainer senses drop in voltage it kicks on to take it back to 12.9 to 13.1 volts before going back into float mode. Also since my older truck doesn't have smart alternators like everyone else is talking about in their newer trucks will agms be ok to run and not have a overcharging issue?

Thanks

 

Don't some of these newer Ford trucks come from the factory with AGM's?

Maybe someone with FORScan can look and see what the SOC is set at for factory AGM's?

 

That is a great question I would like to know too.

 

Since 2023 ALL dual battery trucks come with 750CCA, 68AH AGMs.

 

@Tw3ak

I visited Deltran's website, located the Battery Tender Junior .750mA maintainer, read the webpage, downloaded and read the Operator's Manual, and chatted with the chatbot on Deltran's website.

And through all of that research, there is no place that states what the charging VOLTAGE is of that charger. Deltran's chatbot said "12 volts". I reminded Deltran's AI Bot that Deltran's own website defines a fully charged battery is being between 12.7 to 12.9 volts, so how can a charger output of 12 volts charge a battery to 12.9 volts? The chatbot agreed, and suggested that a human needed to be contacted.

So that is what I suggest for you to do. Contact Deltran to determine the range of charging voltages that the maintainer charges at. Determine if the .750mA is a constant current, irrespective of voltage. Ask if the maintainer is temperature compensated. In other words, get the electrical specs, because all that is on the Deltran website is green marketing blather, and all that is in the Manual are user safety warnings to reduce Deltran's consumer liability.

Battery tenders can maintain charged batteries, but are not suitable for charging depleted batteries, even if left on the battery for weeks at a time.


A battery maintainer in principle will not damage a fully charged AGM battery, provided the charging voltage of the maintainer is within the optimal range for float charging the AGM battery... which for each 2 volt cell, is between 2.25v to 2.30v per cell, or 13.5v to 13.8v to maintain the charge of a 12v nominal battery, at room temperature.

The warmer the temperature, the lower the charge voltage should be. The colder the temperature, the higher the charge voltage can be. A rough figure is for every 1°C change in temperature, the charging voltage should be adjusted 18 mv up or down, cold or warm, as the case may be. A smart battery maintainer, that has two leads to the positive clamp, where one lead is to measure temperature, while the other lead is to carry charging current, is more likely to optimize the charging voltage to suit the internal temperature of the battery.

AGM batteries also self-discharge at a higher rate in warmer temperatures than colder temperatures. But AGM batteries don't freeze like FLA batteries do in sub freezing temperatures. Enersys advertises a 2 year shelf life for their Odyssey Extreme batteries to maintain their state of charge... but that is at 25°C (77°F). If the same battery was stored at 35°C (95°F), the shelf life before needing a refresh charge would be reduced to only 1 year. If stored in the hot summer of Arizona at 45°C (113°F), the shelf life before needing a charge would only be 6 months. On the other hand, if the battery were stored in 5°C (41°F), it might last as much as 4 years without needing a charge, provided it wasn't being parasitically drained.

Your batteries are being parasitically drained, but the explanation of temperature above was simply made to illustrate the dramatic difference that temperature can make, and why maintenance chargers with temperature sensors can be better for battery charging (bulk and absorption) as well as maintaining (float and periodic pulsing).




Note the 13.2 volt bottom line threshold.

So if the Deltran chat bot was correct, and the .750mA Battery Tender operated at 12 volts, or anything under 13.2 volts, then that low of voltage isn't recommended, because the lead sulfate formed from discharging will never get dislodged, and the plate grids will corrode as a result.



Certain types of maintainers can be bad for batteries, and using a maintainer to recharge a discharged battery can be bad, because the low amp maintainer doesn't have enough umph to dissolve the lead sulfate build up on the plates back into a solution of sulfuric acid, leaving only lead oxide on the positive plate and just lead on the negative plate. If lead sulfate crystals are left clinging to the lead plates like barnacles for a long time, the crystallization will become harder and harder, and more difficult to remove, and the battery life and electron moving efficacy will be diminished, permanently.

But using a maintainer, with a regulated voltage, and preferably, with a temperature compensated regulated voltage, is no problem when applied to a fully charged battery, and will actually increase battery longevity, especially in cases such as you describe, where there is a constant parasitic drain on the battery that must be replenished.





This depends on how much of a drop in voltage it senses, and how much voltage it supplies to take it back. Since .750 mA is woefully below the current needed to replenish a 68Ah to 74Ah battery, if the maintainer ramps up the voltage to 15v, the electrical pressure, despite the pathetic current, is enough to generate gassing, without effectively charging.

My older truck doesn't have smart alternators either. I ran my first pair of AGM batteries for 10-11 years. I'm on my second pair of AGM batteries now, which I've been running now for 7 years so far. All on dumb alternators, but with a smart plug in the wall charger. I selected a smart charger with a temperature sensing lead, and a charge algorithm vetted and approved by the manufacturer of the AGM batteries that I have.










A photo of the AGM batteries I use, the day they were delivered by mail, in 2018. AGM batteries are shippable. I was all set to charge them before install, but found that they were already charged adequately as delivered.




Below is the 8 stage (7 stage, in the case of AGM batteries) charging algorithm of the CTEK MUS 25000, from 2015, which has since been replaced by a newer model.





While Enersys approved the CTEK charger back in 2015, Enersys took that approval a step further and partnered with CTEK, in order to offer the same charger under the Odyssey brand name.




The OBC-25-A-1, at $526.99, is slightly different than the older CTEK MUS 25000 upon which it is based.

Instead of the CTEK's 14.4v peak voltage for AGMs at 25 amps, the OBC version ramps up to 14.7v, but charges at only 22 amps, which is less than the 40% of the 10 hour amp hour rating that Enersys recommend for their Group 65 batteries, which happens to be 65 amp hours C10 (74ah C20).

40% of 65ah is 26 amps, so at only 22 amps, the Odyssey branded charger falls that much further short of the Enersys amp rating for the Odyssey Group 65 battery.










An argument can be made for increasing charge voltage Odyssey TPPL batteries by 3 tenths, to 14.7. The grid plate resiliency of high purity lead, and lessor likely hood of alloyed amalgams influencing the conversion in charging, may have inspired Enersys to uprate the charging voltage to better recover deeply discharged batteries.



However, for other brands of AGM batteries, such as the Varta made AGM batteries that are most likely the batteries found in wax and oil auto stores and Walmart (Varta is wholly owned by Clarios), and the East Penn Manufacturing made AGM batteries offered in the Deka brand, the Duracell brand, the DieHard brand, and other recognized name brands are still recommending an optimum of 14.4v at room temperatures.



The above chart also provides voltage guidance for any given temperature range when trickle or float charging.

 

I just checked my '22 F-450. It was set at Flooded, 120%. I have no idea what algorithm applies to each of Ford's percentages; didn't like the sound of 120% so changed it to 100%. I'll change the type to AGM next year when it's time for new batteries.

Earlier this year, Ford replaced one of my batteries and the hold down bracket because the battery was leaking at the caps. No idea if that is because of the 120%; but possible.

PS: I checked the part numbers and my twin alternators (240A & 157A) are not smart alternators.

 

726-06-01 **** xxxx xxxx BMS SOC Critical Cfg
726-06-01 xxxx **** xxxx BMS SOC LSoff Cfg
726-06-01 xxxx xxxx **xx BMS SOC Max Cfg
726-06-02 **xx xxxx xxxx
726-06-02 xx** **xx xxxx BMS SOC Off Cfg
726-06-02 xxxx xxx* xxxx BMS SOC QF Check Enable: 0=Disable, 1=Enable, 2=Disable
726-07-01 0000 1388 05D5
726-07-01 xxxx **** xxxx BMS Start Delay Time Cfg
726-07-01 xxxx xxxx **xx BMS Target SOC Cfg
726-07-02 **xx xxxx xxxx
726-07-02 xxxx xx** **xx BMS Time LS off Cfg

Battery Target State Of Charge %


When fellow members refer to what Ford refers to as SOC... it can be confusing what members are referring to.

And, it can be confusing what Ford is referring to.

Does "Target State Of Charge %" refer to

1. The State Of Charge of the battery before initiating an action?

2. The State Of Charge of the battery before ceasing an action?

3. The State Of Charge to bring the battery to?

4. The State Of the Charging system voltage to charge the battery at?

5. If the truck has an AGM battery, and the battery is considered fully charged at 12.75 volts, is the State Of Charge % the percentage over and above the 12.75 volts that battery is considered fully charged, that the charging system has to operate at in order to bring the battery to a fully charged state?

Some examples to illustrate a possible (but not proven) interpretation of what is meant by "Target SOC %" as defined by Option #5, at 25°C:

5a. 12.75v (Target SOC) x 120% (Target SOC %) = 15.30v (High and gassy rate of charge for any battery, and too high for an AGM battery.)

5b. 12.75v (Target SOC) x 115% (Target SOC %) = 14.66v (Goldilocks "Just Right" perfect charge rate for any battery, Max rate for AGMs.)

5c. 12.75v (Target SOC) x 110% (Target SOC %) = 14.03v (Kind of too low of charge rate to desulfate plates, and only barely in the ball park.)

5d. 12.75v (Target SOC) x 100% (Target SOC %) = 12.75v (No difference between target battery voltage & target charging voltage = no charging.)

5e. 12.75v (Target SOC) x 90% (Target SOC %) = 11.48v (Abdominally low. Battery voltage higher than charging voltage, becomes an 11v battery.)

5f. 12.75v (Target SOC) x 80% (Target SOC %) = 10.20v (Members report finding/changing Target SOC% at/to 80%. How is this even possible? Must not be #5.)


What do members mean by Battery Target State Of Charge %?

What does Ford mean?

Do members and Ford mean the same thing?

 

From my 2024 F-450 6.7HO with dual factory AGM. Values from my VIN's as-built download

726-06-01 0400 0000 0038
726-06-02 0000 0000 0035
726-07-01 0201 0100 3069
726-07-02 0028 0001 0160

 

This is what I have been wondering. I know it has been talked about in other threads, but like you point out, nothing has been stated as to what "Battery Target State of Charge %" actually is, or means... at least as far as what Ford intends it to be, or even what Forscan has interpreted it as. I have seen lots of folks show and state that theirs came set at 80%, as well as 120%. A lot of speculation about this is that 80% is too low, and 120% is too high and likely the reason that batteries are boiling over and failing so quickly. I don't know, but I know that there are also a lot of possible variations, some of which could be gas vs diesel, single battery vs dual battery, single vs dual alternator, smart alternator?, added camper package or not, even fuel mileage... and so forth. And considering so many are set at 120, I am not completely convinced that it was a mistake on Ford's part, although I am not convinced that it couldn't have been a mistake either... like everyone else here, I just don't know.

I was also looking at the "Battery Configuration" line in the BdyCM and it was set to PWM. I opened that box up and there were 3 settings: Off, LIN, and PWM. I left it on PWM. I don't know what that means here. I do know that when buying my solar chargers for my camper, I went with MPPT rather than PWM, but I don't know if it is the same PWM charging method here in the truck... I also searched for LIN and came across a lot of talk about it in some Transit forums, in conjunction with a smart alternator. It seemed that many of these post stated that the Battery Target SOC% in their Transits were at 80%... and somewhere in there I came across a lot of talk about it having something to do with making sure the alternators would also charge house batteries when connected...

When I installed my AGM's, I did change battery type from flooded to AGM, and I reset the BMS. Forscan even added a note when resetting the BMS that this should only be done when installing new batteries, so I feel pretty good about both of those changes. I did also lower the Battery Target SOC% from 120 to 100, but I am still thinking this one out and wondering if I should go back up to 120 or leave it at 100. I was hoping that maybe by changing the battery type with Forscan first, that it may trigger that SOC% to automatically change, but no such luck... So, I lowered it to 100%.

To further confuse things... I have also been using the Battery Voltage BID on my Banks iDash for the last couple of years. However, there are 2 different choices for the Banks BIDs; ECU Battery Voltage and B-Bus Battery Voltage. I have assumed (which means I really don't know...) that the ECU measurement is what the ECU is either reading what the current charge is at, or is the charge that is needed to charge the battery. I also assumed that the B-Bus voltage is the reading of the charge being sent to the batteries, at the batteries...? Like I said, I don't know... For whatever reason, I chose the B-Bus voltage BID and that is where it has been. With the OE FLA batteries, I have seen it read anywhere from 14.7 down to about 13.7 (when the engine was running). Since installing the AGM's, resetting the BMS, changing the type to AGM and then letting the batteries charge all night long after I put them in using a NOCO Genius10 charger, the B-Bus V on the iDash read 14.7 on the entire drive to work the next morning. About 13 miles and 39F outside. That afternoon on the way home at about 60F it read 14.6 and occasionally flipped over to 14.5. I plugged the charger in agin that night, and the next morning at about 50F it read 14.2 on the way to work, and then on the way home at about 58F it read 13.8. We went out for dinner last night and it stayed at 13.8 for that drive too. I did not hook up the charger last night and I have't been back in it this morning to see what it reads now...

 

@chadstickpoindexter

Thank you for fleshing out the feelings behind the ambiguity in interpretations over the meaning of "Target Battery State of Charge %."

It appears that the state of charge of your newly installed batteries are trending toward a state of decline, ever since made changes via Forscan to several parameters in your truck's PCM.

My concern, on your behalf, is the change that you made to the "Battery Target State of Charge %", from the original 120, down to 100.

The popular, forum fueled reasoning for that change includes:

A. 100 is a happy medium between 80 and 120.

B. 120 is where folks report actually hearing the water in batteries boiling, see and smell severe outgassing, deal with corroded battery terminals hold down brackets, find wetness on top of the battery,

C. 80 is where folks report short battery life (yet this is also the case at 120)

D. 100 is what someone with a popular following on YouTube says that he does.

However, without understanding what is meant by Ford, either semantically as to what is being described, or functionally as a result of a numerical value change, how can folks know what they are changing?

To this you brought up another nuance... how does FORScan, the diagnostics software from Russia that most folks use to make these changes, as it is (or was) the only affordable option available, interpret, in both language and function description... the meaning of "Battery Target State of Charge %." Does it differ in any way from what a Ford dealership technician might see in the service bay FDRS, or with an IDS?

Even assuming there is no difference, the ambiguity remains.

It is good that you didn't hook up the charger last night. If you find the battery voltage continuing to decline, may I suggest that you restore your "Battery Target State Of Charge %" to 115%, as an experiment?

Leave the other settings to AGM, and then recharge your batteries with the wall charger to restore them from the deeper discharge that led you to discover their decline, and then stop plugging in the batteries for a while, as you monitor the truck's state of charge at the end of your driving cycles, after you changed the Battery Target State Of Charge % back up to 115.

If you decide to try this suggestion out, please report back with your findings.

 

I will admit, I went with 100 because I thought that 100% is just the normal and "right" number... if that makes sense. But I will admit, it was purely a guess for me, and it is the one that I continue to think about and wonder if I should have just let it be... After reading your earlier post I did think about going out and changing it to 115 though...

Also, I went out and moved the truck earlier this morning so my wife could get her car out of the garage. It was 37F outside and the truck was not plugged up last night. When I cranked the truck to move it, the iDash reported 14.7 for the 45 seconds that the truck was turned on to move it out of her way... It has started to warm up outside now and I will keep an eye on it today when I leave to see if it stays at 14.7 again, or if it comes back down.

And just curious what your thoughts are to the iDash BID... as I said, I am using the B-Bus Voltage, and just assumed that this number represented the voltage at the terminals. I also assume that this isn't the actual batteries state of charge, but rather the voltage charge at the batteries from the trucks alternator.

 

Thank you for posting all this info. Once I get my new batteries I will drop to 115%. Maybe I should do it now to see if they stop off gassing.