2021 f150 2.7 replace battery

[fordtruckman2003]

My truck is supposed to have the 800 battery and has 760, fully charged the truck sees it as 75% charged. Tried doing the reset process and that's all I get. Is it because it's a smaller battery?

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[jmargo]

Found the same issue. 2021 Lariat with the 3.5L and the auto stop/start stopped working. Battery is a 760. When I put my VIN in the ford parts page it shows both the 760 and 800 as applicable to Lariat.

 

[RcFlyer330]

My truck is supposed to have the 800 battery and has 760, fully charged the truck sees it as 75% charged. Tried doing the reset process and that's all I get. Is it because it's a smaller battery?

No, the battery magament system (BMS) will only charge the battery to between 75 and 80% max that is what the system is set to do. I can not tell you why it is set to do this but my guess is it has to do with the agm battery chemestry and the charge profile of an agm battery. There is a way to use forscan to up the max charge percentage so the vehicle will charge up the battery more.

 

[Davecp114]

I had the exact same problems everyone is describing here. I have a 2021 XLT Supercrew 4x4 with the 5.0L with the 302A package. I took my truck to my dealer three time and complained about no auto-start/stop not working unless I changed the battery with an AGM approved charger. After doing so, it would function for 3 days or so. At all three visits, they told me that my battery was OK and they couldn't replace it. They also said that the charging system was working as designed. They also said that all my modules were up to date even though I was stuck on OTA update 2.7.4 since October of 2022. After many calls to Ford without any help and just a lot of frustration, I decided to fully charge the battery and leave it disconnected overnight. 12 hours later, the battery was down to about 75% state of charge. That day, I replaced the battery with an identical Motorcraft battery (760CCA) that I purchased from a friend with a wholesale parts business. I also tested the new battery and it had a 92% state of charge before I installed it. The replacement battery has a day code of 1/2023 and held it's charge since it was manufactured. My truck has had the new battery in it for about 6 weeks and the battery discharge problem has not occurred since. I did read that there was an OTA update that changed the charging system curve but I don't think that had anything to do with my problem. I have an 18 mile commute each way to work 5 days a week and the problem was fixed even before my truck started getting OTA updates again last week. I'm now on 3.5.4 and everything is still working fine. I wasn't happy about buying a new battery but I was tired of the dealer and Ford run-around just because the Rotunda battery tester at the Ford dealer said the battery was OK.

@Ford Motor Company ..... It's nice you've been saving a bunch of money on replacement batteries but this is poor customer service on a truck sold for premium money. Why should I have to buy a battery for a truck still under warranty? I also saved you more because you avoided a roadside assistance tow which would have cost you more than the battery that would eventually fail. How is Ford going to make this up to me...a lifetime Ford owner on 4th new Ford since 1990 (plus 7 I'm the 2nd owner)??? Why should I buy a 5th new Ford or should I give a new Toyota Tundra a shot next time??? I know there are a ton of posters out there making guesses at technical problems but I'm a former Ford technician with some Ford knowledge and training....look me up in STARS. Does @Ford Motor Company want to make me a happy customer or do they even care??????

 

[Ditt7]

2021 F-150 Lariat 3.5 EcoBoost

I've been suffering from the battery drain/dead battery issue described in this thread. Last week, I purchased a new DieHard H6 Platinum battery. 2 days w/out driving and the battery was drained by almost 50% and my truck wouldn’t start. I charged the battery and then set up my multimeter in series with the negative battery terminal to check the mA draw. I watched as the different modules went to sleep (doors closed nothing on inside the truck). The draw settled down at about 11 mA. Good.
The next morning I checked the voltage on the battery and it was down to under 12V. ?
This led me to believe that something was happening overnight that cranked up the draw on the battery. I thought about this for a while and remembered that I have Automatic Updates set to occur every day at 1:00am. I was suspicious and turned off Automatic Updates to see if anything changed. It’s been several days now and I’ve been checking the battery voltage every morning. No issues so far. Truck starts right up and the diagnostic mode (brake pressed, steering wheel OK button pressed when starting) shows 12.6V to 14.6V.
My belief is that when Automatic Updates kick in the connection services (WiFi/cellular) activate but don’t properly DEactivate when complete.
I’m going to continue monitoring but looks good so far.
Anyone else try shutting off Automatic's Updates?

 

[fordtruckman2003]

Even with automatic updates turned off your truck will still wake up and phone home. H6 is tiny battery with low capacity. Think bigger. H7 for Powerboost or H8 for the rest.

 

[Ditt7]

My apologies. H6 was a typo. I replaced it with an H7.
Why do you believe that connection services would still activate without performing a check for updates?

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