I asked this question before in another post and never really got an answer.Can I replace my agm battery with a regular battery.I have a 2018 xlt with the 5.0 engine.The engine start stop function has been disabled.

 

No. Ford specifically states agm batteries. The charging requirements are different. If you replace it you will also need to do a battery monitor reset with a scan tool. Did you recently have a reflash done to the pcm or is the battery just bad? There are a couple of reasons why the start stop function will not work.

 

I wouldn't

Quote:
An AGM battery is a car battery designed for two jobs: delivering powerful bursts of starting amps and running electronics for a long time. And here's the big deal: They tend to last longer than a regular flooded battery. ... In turn, manufacturers can squeeze more glass mats and lead into one battery.

Your truck needs the agm for electronics if nothing else.

 

This is true. One other thing that an AGM battery does is tolerate a slightly lower SOC (State of Charge) compared to a wet cell lead acid battery. In most cases a wet cell will tolerate about 50% SOC, whereas most AGM batteries can go as low as 40%. This is not true across the board, as each manufacturer is a bit different, but is true as a rule of thumb.

 

See the junk batteries thread for a lot of views. I just replaced my 2018 Lariat 5.0 because I'm going cross country next month.......It tested 80%

 

How did you disable the engine start/stop?

 

I have a tuner and as part of the programing you can disable the start/stop function.

 

Lot's different solutions. As said, a tuner can do it, or you can add a start/stop eliminator, or you can do it via Forscan, or you can put a dummy plug in one of the trailer electrical connectors. You could even jumper the back of the switch to force the issue.

There are at least a couple of threads on this issue, just search for "start/stop" and get a feast.

 

If you don't tow a trailer, unplug little connection on brake module close to brake pedal. Bottom plug. For me, I bought the eliminator for $90.

 

There is a major difference between Lead Acid battery construction and AGM.
The Battery management system has to be set to the battery type installed.
The AGM should not be charged at a voltage level above 14.6 volts.
The Lead acid is charged at well above that level as high as 16 volts.
You see, putting a Lead Acid in place of the AGM results in too low a charge level.
Going the other direction with the battery can result in a charge level too high for the AGM. Results of this is short battery life.
.
Resetting the age record is important to total battery life with both types of batteries because the system keeps track of age, temperatures and state of charge to estimate how the system handles the battery at any given time. If not done, the system treats the new battery as if it is still the old aged one that was taken out and can result in under charging or over charging. The estimate method is based on known battery type characteristics vs age, number of starts etc kept elsewhere in memory.
Most of the data used for the system comes from the negative cable sensor located at the battery terminal. Pull the plug from it and your out of any control the system provides, you paid good money for. Also if defeated, some engine performance is also lost such as low charge rate on acceleration, fuel mileage and other hidden advantages designed into the overall system.
Switching battery types has to be set in the system to tell how to handle the battery installed if it was changed to another type.
If has to be understood these systems of control are way advanced from the old Alternator/ Regulator days.
If not respected, the battery life can be shortened by just by ignorance and some performance lost.
.
Now for an experience:
2018 5L with 4-year-old AGM battery.
Battery was performing very well for that age with no issues.
Another person left the parking lights on for 4 days as I found when trying to start the truck with a dead battery later on.
The battery voltage was down to (4 volts).
At this point a jump start was not even successful across the battery.
Bottomline was the AGM battery was damaged beyond recovery.
New AGM installed and all, is ok.
I notice the new battery voltage is a couple tenth higher in voltage than the aged one that was taken out before the damage occurred. Tenths of a volts is very important to charge level and cranking ability and where high amperage is involved.
Chalk that up to the difference in age and use.
Now the start cranking RPM is very noticeably higher.
Battery voltage/system performance can be looked at in the >dash engineering mode< if called up and stepped to look at it at resting, cranking and running values.
There is no need to guess at any of this.

 

Added info for today.:
Looked at State of charge cold before starting = 12.6 volts. This is a 75% charge that is normal per general service bulletin page 2.
Ambient temperature of battery was in the 38 to 40 degree range.
After starting, the charge voltage was 13.6 volts. This is right in line with what the charge controls the system does for cold temps. Refer to page 7 of GSB.
As the truck was driven and battery temp increased, the charge voltage increased to the 14,5 volt range right in line with the max charge permitted for AGM battery.. See page 8 >note<.
.
Bottom line is not to dismiss the factory design and system performance per battery type, if you care.
Take the time to read and fully understand the GSB doc per the type that should be in the vehicle.
Just making changes of any type and saying it works fine is not really satisfactory over the long term.
Good luck.

 

How does one get to the dash engineering mode?
Thanks TJ

 

Press and hold the "OK" button on the steering wheel as you start the truck, then release when you see "ENGINEERING TEST MODE". You can then scroll through various bits of data.

That is the way it works on our 2015, and your 2018 is "probably" the same.

 

The left button will need presssing 42 times to reach the charge system data for 2018 model year.
My 02 had the same capability.
That's 19 years ago.
Good luck.

 

I replaced my AGM battery with a regular battery (Not intentionally) it worked fine for about a month then I would get a system shut down message on my screen saying that the system was shutting down to preserve battery. This would happen almost every morning in the exact same spot on my way to work then the system would restart in the exact same spot about 4 miles down the road. Sync 3 system shut down, audio, automatic high beams on auto Start/stop feature. The last two didn't break my heart but no music was frustrating. I thought it was my charging system failing but after spending $168.00 for a diagnostic it was determined that I was given the in correct battery from Costco. Lucky for me Costco took the wrong battery back after ten months and only charged me $31.00 for the difference. Have not had any issues since the swap out of batteries.