In a post below on DUAL BATTERIES there was a discussion about removing the wire to the pickup coil on the negative terminal of the battery. That is suppose to DISABLE the Battery Management System and make the alternator function all the time and charge the battery similar to how things were done prior to 2010..

My question is, WHAT GOOD is the BMS ? Why did FORD spend the money to install this ? What problem were they trying to fix ? Is there any advantage to having BMS ?

 

I disconnected mine 6 years ago after waking up to a dead battery trying to get to work. Not a problem since then.

What you're doing by disconnecting that sensor is allowing the alternator to charge all the time like cars/trucks have been doing for the past 100+ years now? What I know about how it's designed is it turns off the alternator when cranking the engine so it starts quicker and it employs a load shed strategy in which it will turn off other circuits when battery voltage gets critical. Early versions didn't work as expected.

I have the early version.

 

Thats my point... the MODIFICATION had to COST MONEY... WHY do it ? WHAT did they gain ?

 

You would have to consult with a Ford engineer to get that answer.

 

Well you don't have to go to far to understand the benefits of BMS systems. The benefits are for the manufacturer not the end consumer. The BMS does increase overall efficiency and every fraction of a MPG counts in the game.

 

Are you talking about your 2013 truck? I'm not sure about that year. on newer trucks the BMS is required for the start-stop feature to work, which saves fuel, and it also allows the alternator to not create as much load once the battery is charged, which again, saves fuel. I don't know if it saves an wear and tear on the alternator, or has any other benefits.

 

According to the manual it is supposed to extend battery life. Battery Management System (If Equipped)

The battery management system (BMS) monitors battery conditions
and takes actions to extend battery life. If excessive battery drain is
detected, the system may temporarily disable certain electrical features
to protect the battery. Those electrical accessories affected include the
rear defrost, heated/cooled seats, climate control fan, heated steering
wheel, audio and navigation system. A message may be shown in the
information displays to alert the driver that battery protection actions
are active. These messages are only for notification that an action is
taking place, and not intended to indicate an electrical problem or that
the battery requires replacement.

 

When the BMS knows the condition of the battery it can do things like reduce alternator drag when under heavy throttle (helps performance), reduce charge rate at cruise (helps fuel economy), or max alternator charge rate when decelerating if the battery needs it (helps braking). As said above, every little advantage is baked in where ever possible.

 

YEA... well i let the truck set for 2 weeks no operation, then after short run, sat and listened to the radio... BMS shut system down after 2-3 minutes with a NOTE that it was doing it......... Got home and charge the battery STRIAGHT to the negative terminal... Next day, FULL BATTERY and the BMS still gave the "shut down"... so it has NO CLUE what the battery condition really is... Charge again by moving the negative clamp OUTSIDE the pickup coil and it figured it out after that....

After setting for 2 weeks and then driving for 15 minutes on the road, WHY didnt the alternator do a quick charge at 50 - 100 amps to get the battery back up tip top ??

So basically my conclusion is the BMS does NOT know the battery condition... just the load in and out.

 

Similar issue with my ‘17 Expy. But if mine sat for a week it wouldn’t even START!

After charging the battery (with the negative charger cable on the fender well) it would start up and all was good until it sat for while.

After a few weeks of this, finally threw that 2+ year old Ford battery away and put an AGM in there and haven’t had to look back since. BUT, I did reset the BMS when I installed the new battery.

So, perhaps your alternator did throw some high voltage at your battery and it couldn’t hold the charge? Don’t know.

 

The modern trucks are trying to do a lot more than the ones 10 years ago, and yeah, sometimes it doesn't do what we want. I've basically decided that everything needs a battery tender if it's going to be sitting more than a week.

 

My OE battery finally crapped out after 7 years. Rather than deal with the documented problems of a different battery, I turned to my local dealership for a replacement. For 8 or 10 months now it seems I have no battery reserve. The BMS turns off power to radio and aux ports within 2 minutes claiming low power. I've done everything everyone has recommended- BMS reset several times, checking connections, charging system checks, parasitic draw, everything. I even tried a different battery. Nothing helps. And like you, I've found if I let the truck sit for 3 or 4 days, the battery is weak. If I let it sit for 2 weeks it barely starts the truck and sometimes it won't. Same thing with 2 different batteries, one of which was brand new. But if I hook a tender to it it's fine.

 

which "BMS reset" did you do? the one where you let the battery sit overnight, or the one in forscan that resets the age of the battery? It's also possible that your "new" battery is no good. It happens. Have you had it load tested somewhere?

 

Both BMS resets. The "let it sit undisturbed" several times. I thought I was clear in my post- I bought a 2nd new battery and tried resets again to find no improvement.

 

SO........ the conclusion is... BMS =