Ford Authority

Ford Battery Monitoring System Explained In Depth By Technician

Blue Oval technician and YouTuber Ford Tech Makuloco creates some truly fascinating and informative content on a regular basis, and over the past several months, has helped us learn more about some general Ford EcoBoost problems including a common Ford 2.0L I-4 EcoBoost coolant issue, coolant intrusion with the Ford 1.6L I-4 EcoBoost, a problem with the Ford F-150 remote start feature, and how to diagnose and fix a rattling issue with 2017-2020 Ford F-150 pickups equipped with the twin-turbocharged Ford 3.5L V6 EcoBoost engine. Now, our resident technician is back with a new video explaining the Ford Battery Monitoring System (BMS) in depth.

The Ford Battery Monitoring System has been around for well over a decade at this point, and as such, is present in quite a few vehicles on the road today. That includes the 2013 and 2021 Ford F-150 pickups present in our host’s shop at the moment. As one might imagine, these two trucks utilize a different version of the BMS, as it has evolved over the years. While the newer pickup has been reliable thus far, there was a particular issue that popped up that required a bit of attention recently, as explained here.

Short trips tend to pull more amperage than the charging system can put back into the battery, which causes certain features – such as auto stop/start – to stop working. Other times, the infotainment screen may display a message that the system has turned off to save the battery. Those that drive longer distances don’t necessarily see this happen quite as frequently, as the charging system is able to keep the battery at an optimum state of charge.

In a world where vehicles continue to gain more and more technology features, Ford’s BMS is rather important. After all, no one wants to hop in their truck and find that the battery is dead, and that’s precisely why BMS automatically shuts down certain features when needed. It may be a bit inconvenient at times, but it sure beats getting stranded with a dead battery when one needs to be somewhere posthaste.

We’ll have more videos like this to share soon, so be sure and subscribe to Ford Authority for the latest Ford F-Series news, Ford F-150 news, and non-stop Ford news coverage.

Brett's lost track of all the Fords he's owned over the years and how much he's spent modifying them, but his current money pits include an S550 Mustang and 13th gen F-150.

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  1. Bill Howland

    The thing I find amazing is that the car draws 18 amperes with the ignition on…He didn’t specify (which would have been super easy to do) what the drain was with the ignition off. Things like power electric steering and brakes should only draw power when the steering wheel is turning or the brakes applied….

    I did notice a problem when putting a 2011 volt in ‘maintenance mode’ where the 12 volt battery isn’t charging…The car radio went dead after about 2 hours…. So there was a huge amount of juice being drawn, but then, that car has an electric oil pump which runs at various times when the engine is off… I though THAT aspect of the car was a poor design…

    On this ford I just don’t see why the power consumption should be that high…. Of course it will grow while driving – so short trips at low engine rpm will cause many dead batteries….FORD needs to in that case, with this ridiculous power consumption – either fix the quiescent loads or else barring that, put in a low-cut-in alternator – of which plenty of aftermarket alternators provide.

    1. RWFA

      Can’t imagine why an oil pump would cycle like that unless there is some kind of risk of metal on metal scuffing on startup.

      1. Bill Howland

        Oil pump lubes everything up prior to engine start up – plus runs the clutches when in electric mode.

  2. JDE

    might want to look into the BBAS manuals for all fords these days, thanks to the many parasitic draws on the vehicle including just keeping the memory for the trans, these vehicles need the battery disconnected if it is to be stored more than 30 days. 2 weeks or more and you need to do a specific length loop to get the battery up to the correct SOC. Honestly though that does not always help. many times the AGM battery just sulfates and then there is no chance of recovery. the batteries just fail very early. It would be better if the BSM either disconnected the battery altogether after a certain point or auto started the vehicle occasionally, but both would be dangerous i suppose, so here we are. the sad truth is the big Battery in the lightning should be able to keep the 12V acc. battery charged indefinitely during storage, but even so, the recommendation is to disconnect it if storage is planned for 2 weeks or more.

    1. Bill Howland

      Ford joins other manufacturers with silly battery management schemes that function in effect much worse than just monitoring the voltage of the battery, which is the way batteries charged for over 90 years uneventfully.

      As far as memories go, there is no reason a hearing aid battery shouldn’t maintanin any memory function for a year or so. Horrible designs all around.

      Assuming all these car companies are stuck with their bastardized designs – the band-aid solution of course is to provide a low-cut in, and/or bigger alternator as I’ve already mentioned.

      But you would think all those white-collar engineers would have half-a-brain about stuff in the first place to never run into these problems. A vehicle just sitting with the ignition on is not doing 216 watts of valuable work, which is what 18 amperes is.

  3. Albert Donovan

    I have a 2021 F150 3.5 Eco boost Lariat. The battery has been dying since I bought the truck. I presently has 1054 Kilometres on it. The battery has been replaced. it had died 4 times already and ha had to be boosted each time. Some computer has been re-programed. They say it might be the light switch that is possibly coming on when the truck is parked over night. I turn the light selector to the off position when parking in the garage and the next morning it is in the auto position. The battery needs to be put on charge if I leave the truck parked more then three nights. Apparently a new light switch won’t be available till maybe Dec. Can you help me out with this problem.

  4. David

    2012 f-150 how do I reset the BMS when installing a new battery

    1. JDE

      you have to have the FDRS/IDS system at home, which means you have to be a dealer.


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