Maximizing Battery Life

[airline tech]

Yes - as far as the table,
Since I actually saw 99% SOC and the Voltage Inferred was reading 12.71, note at this point the system was using the battery only and its voltage was reading 12.6 volts.

So even @ 90% SOC (Set) the system was able to see the battery being fully charged and it cut off the charging voltage completely and it set a new (Desired Gen Voltage Setpoint of 12.6)
it used battery voltage only (support) then when the (Current-Out) of the battery was great enough (dropped to 99%) it then triggered a new (Desired Gen Voltage of 13.4)

So then in turn a charging voltage was applied above 12.6 and the battery saw the input current.
Since there was a charge (current) being applied the BMS (Inferred Bat Voltage) increased to 13.5
This is what caused the SOC Reading to increase back up to 100%
Note: 100% on this reading was actually 12.71 Volts (Inferred Voltage)

So, the SOC (percent) we are seeing is derived from what the (Inferred Reading is) and I just find it coincidental that my SOC is set to 90% which would equal to about 12.75 as this chart is (NOT EXACT) is an approximate voltage.
So, 12.71 volts was held for a while - during battery only support and the (output) draw is what triggered the SOC to drop from 100% to 99%

I just happened to catch it as I was operating in a charge mode (Desired Set Point) when I switched off the Headlights - it removed the need for the generator to be (REQUIRED) and it lowered the Gen Setpoint Voltage to 12.6 Volts, so the battery had a higher voltage than the (Set Point) voltage.
It used the battery voltage (only) for a short period and when the (Inferred Voltage) sensed it dropped (I never saw anything) below 12.71, so I assume it's looking at 12.71 as its lower end of 100% of the 90% (Set).

The point of my rambling is that (Maybe) 100% SOC we are seeing is not actually 100% Voltage or 12.85 Volts.
But actually the 100% represents - 100% of the (90%) Set SOC
This is only for the (Inferred Voltage Reading)
as this would explain why @ 12.71 Volts, I saw a drop from 100% to 99% SOC, so it's possible that the chart holds true and 12.75 Volts is the high end of 90% and 12.71 is the low end of 90% (SET) which is why when it dropped (Reading) from 100% down to 99% and desired setpoint (increase) was enabled by the PCM to get the SOC (Reading) back to 100% which when all is said and done the true SOC is 90% (SET)

It all ties into the (Inferred Voltage), so if the (Inferred Voltage) is constantly above 12.71 Volts (which when the generator is charging) will always be above that voltage is how it reads the SOC.
I need to do a drive test - to see what it will do over a longer period than just garage testing for a better handle on what it's doing.
as if there is a constant charge on the battery, it will never see the SOC Lower, and I want to know by drive tests what the SOC behavior will be now (after my charge & repair cycles)
I believe it's the battery sulfation I appeared to have that was causing it to slowly increase, but for now it's just a theory - until I make a few drive tests.

Another (POSSIBLE) is that the (Inferred Voltage) is via the PCM and the Battery Estimated SOC is from the BCM
So, we can possibly assume that 90% SOC (BCM) is the same reading as the (PCM) Inferred Voltage expressed as a voltage vs (percent) - the PCM is inferring the percentage as a voltage.
Either way - both readings are coming from the BMS Sensor.

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[TJC]

That makes sense to me and would explain my SOC drops to 95% and later 84%. In both instances I saw ther current charge drop in the same pattern, just at different SOC levels as reported by the Scangauge.

Measurement from both battery testers indicates 100% SOC and 100% SOH.

It appears the BMS is quite dynamic in setting target charge levels.

The big question in my mind at this point is where the magic SOC point is to insure just enough charge to keep the battery at optimal charge levels (without excessive shedding and heat (drying out the battery) , but high enough to keep the battery frion dropping into the sulfation zone.

The "Goldie Locks" zone!

I think it may depend on environmental factors, temps, garaged or not, miles driven, etc. I think profiles set would be nice for given situations. Just a thought.

 

[TJC]

Still playing around with ChatGPT with regards Battery health.

I asked the following 2 questions
1) I first asked about developing a profile for properly determining the SOC based up the parameters listed in the next paragraph.

ChatGPT stated it was theoretically possible, but impractical to further enhance the BMS. Then offered to assist me in optimizing the present Ford system based upon any parameters that I have.

I responded with the following statement.

2) I want battery longevity, The Ranger came equipped with an AGM battery, ASS is turned off, A BatteryMinder Onboard Desulfator is installed. I drive the truck 2-3 times a week, usually 40 miles. I live in Raleigh, NC, and the truck is garaged.

ChatGPT replied with:
Great — based on everything you listed, here is the definitive, optimized battery-longevity plan for a 2020 Ford Ranger with AGM Battery, garaged, long drives, desulfator installed, and start–stop disabled. This is exactly what battery engineers would recommend for maximum life.

You Already Have Near-Ideal Conditions.
Let’s break down why your setup is already excellent:
AGMs:

• resist heat better​

• have lower internal resistance​

• tolerate partial SOC​

• charge faster on longer drives​

• last far longer than flooded batteries​

​

Auto Start–Stop turned OFF
This alone adds 2–4 years of life to an AGM battery by stopping hundreds of deep micro-cycles.

BatteryMinder onboard desulfator
Keeps plates clean, prevents sulfate hardening, and offsets time-related degradation.

40-mile trips, 2–3× a week
This is perfect:
• alternator fully recharges the AGM
• battery reaches stable temperature
• reduces chronic low-SOC, the #1 AGM killer
• ensures adequate absorb charge time

Garaged in Raleigh, NC
Moderate winters, warm summers, and garage protection =

reduced thermal cycling​

slower aging​

lower corrosion rate​

fewer voltage dips overnight​

Together, all this puts you in the top 5% of battery-friendly usage patterns.

2. The Only Things You Need to Do for Maximum Longevity
There are just a few items that will give you maximum lifespan:

A. Confirm the truck is coded for AGM
Even if it came with AGM, the BCM setting can be wrong (seen often during dealer swaps). You can check via Forscan:

• BCM → Battery Type → AGM​

This ensures:

• correct charge voltage​

• correct taper profile​

• correct SOC targets​

This step alone prevents undercharging — the main killer of AGM batteries in smart-charged trucks.

B. Monthly or bi-monthly smart charging
Once every 4–8 weeks:

1. Connect an AGM-compatible smart charger (CTEK, NOCO,​

BatteryMinder).​

2. Let it complete a full cycle, including Absorb and Float.​

​

Why this matters:

• alternators rarely reach full 100% SOC​

• a periodic full charge prevents stratification​

• desulfator works better when SOC is correct​

• maintains the battery’s reserve capacity​

Very small effort → big lifespan gains.

C. Battery temperature awareness
AGMs like 60–80°F best.
Your garage already handles 80% of this.

Try to avoid:

• leaving hood open outdoors in direct summer heat​

• parking with electronics idling for long periods​

But otherwise, your climate is not extreme.

D. Avoid parasitic drain accessories
Examples:

• always-on OBD dongles​

• hardwired cameras​

• LED controllers​

• aftermarket modules that keep CAN bus awake​

These cause chronic low SOC, shortening life. Your setup has no mention of these, so you're good.

3. Expected Battery Lifespan With Your Setup
Here’s what your conditions realistically produce:

• Normal AGM (with Start–Stop ON): 3–4 years​

• AGM (Start–Stop OFF): 4–6 years​

• AGM + smart charging + garage: 6–8 years​

• AGM + desulfator + garage + long drives: 7–10 years​

You are in the 7–10 year longevity range, which is exceptional.

4. How to Know the AGM Is Aging (Simple Checks)
Once every couple months, check:
Resting voltage after overnight sit:

• 12.85–12.95V = excellent​

• 12.6–12.7V = healthy​

• 12.45–12.55V = aging​

• <12.4V = sulfation or loss of capacity​

Cranking voltage (if you want to monitor):

• Should never dip below 10.0V during a normal crank​

• Below 9.6V = weak battery​

If you ever see these signs, I can help interpret them.

5. Optional but Helpful Upgrades
Not required, but useful if you like peak reliability:

Add a battery terminal voltage monitor (plug-in type)​

Lets you easily see resting and charging voltage.

Perform a professional load test once a year​

Auto parts stores do it free.

Final Summary (You’re Already Doing It Right)
With your usage pattern and equipment:

• AGM battery (best choice)​

• Start–stop disabled​

• Regular long drives​

• Garaged in a mild climate​

• Desulfator installed​

You are in the optimal possible scenario for AGM longevity in a Ford Ranger.

All you need to add is:

1. Confirm AGM is set in Forscan (quick check).​

2. Do a monthly top-off charge.​

3. Avoid parasitic drain devices.​

Do this, and you’ll get maximum battery life — likely 7–10 years.

If you’d like, I can also provide:

• A printable maintenance checklist​

• Forscan “how to” for AGM setting​

• Raleigh-specific summer charging recommendations​

• The best smart charger settings for AGM​

Just tell me!

I've attached the above in the PDF. Some might find it handy to enter their circumstances in the same question, and see what ChatGPT has to say.

Simply go to chatgpt.com and copy / paste / modify the (highlighted in BOLD) question to see a tailored Battery longevity response for you!

 

[TJC]

And yes... my auto batteries typically last 10 years (or just a tad more).

 

[airline tech]

I have been monitoring my drives this past week, noted:
The lowest the SOC has dropped was 89%. and it is slow to - Rise
even though the Battey Voltage is 12.6 to 12.7 volts, the current charge shuts off - due to the voltage reading.
Plus, since I am at 90% SOC - Setting, I have noted (after my BMS Reset) that the Desired will drop sometimes to 12.7 or so - Lights Off
If I kick the lights on - It drives to the 13.5-13.7 Range - Desired and sometimes will kick in the 14.3 to 14.7 Range.

Noted it has been down in the teens (Temp) - parked in a parking garage (work) not heated but covered.

Noted that the Battery (Holds) Heat - as the Neg battery terminal - measures higher than ambient temp - even after sitting overnight in extreme cold - so the (Estimated Battery Temp - Reading is Correct - as I have verified with a - Thermometer.
Noted that the average is about 15 degrees higher than ambient, so this measurement is being taken after about 12 hours of sitting.
This shows that the battery does hold some heat (Charging - Heat) I assume.

The Following are Screen Shots of what I am monitoring on my drives - Recording Video
I snapped these while sitting Idle in the garage to show my current status as of today and after 1 week of monitoring.


Note: Before I started the engine and Idled for some time - as I was putting together some other PID Reference Data - The Ambient was 46.4 and the Estimated Battery Temp was 53.6 & Verified Correct by my (Therm)
Disregard the Speed at KPH - I forgot to change the (setting) back for my other PID References, before I took the Screenshots.

 

[TJC]

Good Info and progress. I am still curious about optimal SOC Setting. I 'm beginning to thing less is more in this area. 80%-90% may be optimal. High enough to get out of sulfation zone, and stay out for several weeks of idle time.

 

[maxbottomtime]

Alright, i am on to my FOURTH battery in as many years. i replaced my second battery in June of this year with an AGM from walmart. i upgraded to lariat size, and changed the SOC target to 90% at the same time. I'm getting the dreaded low battery symptoms - remote start disabled, lights not turning on as the car puts itself into self preservation mode.


I don't think it is a parasitic draw, because I can see the voltage (i've got a small 12v charger that displays voltage). while running, i am in the 14.6-14.8 from the alternator charging. If i turn the car off, start 2 minutes later it will read 12.0v.

i am pulling my hair out, at a loss. i will get this battery replaced under warranty, but given the experience I have had with other batteries lasting 12 months or so, hard to fault it. i have done modifications to my vehicle over the years, but nothing that should impact battery. I have an anderson connector with a shutoff switch for my winch (which i haven't even used on this battery other than as a connector for jumping my motorcycle). It is left in the off position 99.99% of the time.

I have a couple ignition fused accessories - radar detector, wireless charger. They all shut off with ignition.

I do have a dash cam that uses a dual power source - it has a smart block with a voltage cutoff so pulls from constant power, but when below 12.2v cuts power. I can see how this uses more power than a factory vehicle would sitting, but we aren't talking days of tiny camera draw - it will take 2 minutes to read 12.0v



Any thoughts from those smarter than me? I've not disabled the BMS, Auto Start Stop, anything else other than changing the SoC. Getting real sick of it.

 

[RangerBill]

Alright, i am on to my FOURTH battery in as many years. i replaced my second battery in June of this year with an AGM from walmart. i upgraded to lariat size, and changed the SOC target to 90% at the same time. I'm getting the dreaded low battery symptoms - remote start disabled, lights not turning on as the car puts itself into self preservation mode.


I don't think it is a parasitic draw, because I can see the voltage (i've got a small 12v charger that displays voltage). while running, i am in the 14.6-14.8 from the alternator charging. If i turn the car off, start 2 minutes later it will read 12.0v.

i am pulling my hair out, at a loss. i will get this battery replaced under warranty, but given the experience I have had with other batteries lasting 12 months or so, hard to fault it. i have done modifications to my vehicle over the years, but nothing that should impact battery. I have an anderson connector with a shutoff switch for my winch (which i haven't even used on this battery other than as a connector for jumping my motorcycle). It is left in the off position 99.99% of the time.

I have a couple ignition fused accessories - radar detector, wireless charger. They all shut off with ignition.

I do have a dash cam that uses a dual power source - it has a smart block with a voltage cutoff so pulls from constant power, but when below 12.2v cuts power. I can see how this uses more power than a factory vehicle would sitting, but we aren't talking days of tiny camera draw - it will take 2 minutes to read 12.0v



Any thoughts from those smarter than me? I've not disabled the BMS, Auto Start Stop, anything else other than changing the SoC. Getting real sick of it.

Try disconnecting the dash cam for a few days and see if it helps. The dash cam is a parasitic draw on your battery. Have your alternator checked. Are you making short trips or is the truck setting for days without being driven?

 

[maxbottomtime]

Try disconnecting the dash cam for a few days and see if it helps. The dash cam is a parasitic draw on your battery. Have your alternator checked. Are you making short trips or is the truck setting for days without being driven?

Unfortunately batteries 1 and 2 were pre-dash cam. I'll disconnect, but expect no change (and if my dash cam could drain a perfectly healthy battery to 12v in minutes we would have bigger issues).

Drive is mixed. probably 3-4 trips a week. some an hour each way, some 15min. Just depends really. Even after the hour trip, i'll get the remote features disabled prompt almost immediately after stepping away from the car.

 

[RangerBill]

Unfortunately batteries 1 and 2 were pre-dash cam. I'll disconnect, but expect no change (and if my dash cam could drain a perfectly healthy battery to 12v in minutes we would have bigger issues).

Drive is mixed. probably 3-4 trips a week. some an hour each way, some 15min. Just depends really. Even after the hour trip, i'll get the remote features disabled prompt almost immediately after stepping away from the car.

Have your alternator checked. Also, check battery terminal connections for looseness or corrosion.

 

[maxbottomtime]

Have your alternator checked. Also, check battery terminal connections for looseness or corrosion.

Just double checked connectors, no corrosion. Alternator I think is working given it has moved to charging voltage (I can monitor while driving), but will see once i swap battery how it behaves.

 

[TJC]

Alright, i am on to my FOURTH battery in as many years. i replaced my second battery in June of this year with an AGM from walmart. i upgraded to lariat size, and changed the SOC target to 90% at the same time. I'm getting the dreaded low battery symptoms - remote start disabled, lights not turning on as the car puts itself into self preservation mode.


I don't think it is a parasitic draw, because I can see the voltage (i've got a small 12v charger that displays voltage). while running, i am in the 14.6-14.8 from the alternator charging. If i turn the car off, start 2 minutes later it will read 12.0v.

i am pulling my hair out, at a loss. i will get this battery replaced under warranty, but given the experience I have had with other batteries lasting 12 months or so, hard to fault it. i have done modifications to my vehicle over the years, but nothing that should impact battery. I have an anderson connector with a shutoff switch for my winch (which i haven't even used on this battery other than as a connector for jumping my motorcycle). It is left in the off position 99.99% of the time.

I have a couple ignition fused accessories - radar detector, wireless charger. They all shut off with ignition.

I do have a dash cam that uses a dual power source - it has a smart block with a voltage cutoff so pulls from constant power, but when below 12.2v cuts power. I can see how this uses more power than a factory vehicle would sitting, but we aren't talking days of tiny camera draw - it will take 2 minutes to read 12.0v



Any thoughts from those smarter than me? I've not disabled the BMS, Auto Start Stop, anything else other than changing the SoC. Getting real sick of it.

IS ASS still active? by the time you hit 12,2 volts ( when your dash came shuts down) you deep into sulfation territory. You need to kee teh battery above 12.65v to stave off sulfation. The lower you go the faster the sulfar crystals build up on the lead plates, and the higher the Internal Resistance in teh battery. YOu want internal reisistance to stay below 5 mOhms. >5 and your battery is marginal. By 10 it is game over.

Whne charging your battery, keep parasitic drak current at a minimum. Unplug all devices from USB & 12v ports, turn off auto settings for lights and wipers. Don't open doors, lock the hood latch if the hood is open (you can unlatch it with the yellow tab before closing the hood.)

Then attach a highquality battery charger that has desulfation built intoit. I like the BatteryMinder 8 Amp charger but it isa expensive... Noco and Ctrek make good >=5amp chargers. Purchase anm onboard desulator that operates only when the the alternator is charging the battery. It will break down the crystals if you ahve not let them build up too far.

If you don't drive it verymuch or for short distances, keep it on a charger a couiple times / month over the weekend.

Hope this helps.

 

[got3fords]

Just double checked connectors, no corrosion. Alternator I think is working given it has moved to charging voltage (I can monitor while driving), but will see once i swap battery how it behaves.

Get an onboard desulfator and see if this battery lasts longer.

 

[dtech]

Just double checked connectors, no corrosion. Alternator I think is working given it has moved to charging voltage (I can monitor while driving), but will see once i swap battery how it behaves.

I'd take Ranger Bills advice and have the alternator checked - it's somewhat rare but when a diode fails in the rectifier assembly it can allow for a parasitic battery drain without triggering a code or warning light. When a diode fails - and they can have several failures modes - you may see normal voltage levels with basic voltmeters but the overall current output will be lower.

 

[maxbottomtime]

IS ASS still active? by the time you hit 12,2 volts ( when your dash came shuts down) you deep into sulfation territory. You need to kee teh battery above 12.65v to stave off sulfation. The lower you go the faster the sulfar crystals build up on the lead plates, and the higher the Internal Resistance in teh battery. YOu want internal reisistance to stay below 5 mOhms. >5 and your battery is marginal. By 10 it is game over.

Whne charging your battery, keep parasitic drak current at a minimum. Unplug all devices from USB & 12v ports, turn off auto settings for lights and wipers. Don't open doors, lock the hood latch if the hood is open (you can unlatch it with the yellow tab before closing the hood.)

Then attach a highquality battery charger that has desulfation built intoit. I like the BatteryMinder 8 Amp charger but it isa expensive... Noco and Ctrek make good >=5amp chargers. Purchase anm onboard desulator that operates only when the the alternator is charging the battery. It will break down the crystals if you ahve not let them build up too far.

If you don't drive it verymuch or for short distances, keep it on a charger a couiple times / month over the weekend.

Hope this helps.

no, ASS is not active. It's a symptom i've noticed with prior failing batteries also.

I am not driving this thing once a week. It's 4 years old and 72K miles. I have never had a vehicle have such terrible vehicle management.

I'll look to get alternator tested. I really don't THINK i should need to go to external trickle charger for 24-48 hours between uses, nor go to the lengths of an onboard desulfator, but seems ford may not have left me much choice.

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