I normally haunt the older truck forums, but I recently bought a 2011 F150, which for the most part is a great truck.

Entirely my own fault, but I left a cooler plugged into the lighter port overnight and drained down the battery. No problem, I have jumper cables, right? WRONG! Who exactly thought it was a good idea to design a battery management system that would shed loads deemed to be inappropriate, leaving you with a dead vehicle that needed a scan tool reset to enable the electrical system?

Now, I get it as far as protecting the electrical system components, but everything I was able to pull up on the subject indicated that the ECM needed to relearn the state of charge of the battery and this could only be accomplished by letting the vehicle rest for 8 hours, or resetting the system with a scan tool. These are hardly roadside diagnosis options. As it turned out, disconnecting the battery, charging it outside the vehicle and reinstalling the battery provided a solution that only took about 2 hours to complete.

Why would there not be an option to reset the BMS system within the resources of the truck itself? Perhaps I am missing something here, but this makes my 86 F150 infinitely more dependable than my 2011 F150. To add insult to injury, it was a GM tech that suggested disconnecting the battery.

Just want to rant, I now can handle a battery failure on the road, but the built in complexity seems to serve no purpose other than to inflate the dealership service profit margin.

 

There is an option and it's in your owners manual, it states after changing/charging the battery to leave the vehicle completely undisturbed for 8 hours, this means lock the truck and leave it be. Or. you could do what I and most other people do, disconnect the bms sensor on the negative battery cable to disable the stupid thing completely. I've had mine disconnected for close to 8 years now.

 

Agreed. I changed my battery only because I got a deal on a new one that I couldn't refuse. Everything was fine until I put the new battery in. With the new battery the charging voltage was constantly jumping between 14V and 12.5V ( I have a voltmeter installed in the dash). Disconnected the BMS sensor and all is normal now.

 

Replaced my battery after 5 yrs, went to my local dealer instead of doing it myself thinking I'd bypass all the BMS crap. Wrong. Just unplug the sensor on the battery negative cable and be done with it.

 

Wait, is this a thing on the 2010's? I've killed my battery a few times from an amplifier failing on the stereo to just being a derp and accidentally leaving the key on at work and never had a problem. But possibly something you may want to do is just unplug the battery completely when jumping the truck to take that sensor out of it. I had a Galant that was sort of like that. The alternator had a relay of some sort on or close to the alternator and it'd just completely disconnect the battery from receiving a charge...I believe it was to help prevent an overvoltage or something. So I just unplugged both the positive and negative and it worked fine after 3-5 minutes.

 

2011> with BCM. 09-10 don't have that system.