Ford BMS Battery Monitoring System: How it Works and How to Properly Charge Your Battery!

[AzScorpion]

This thread should be a sticky because it answers so many common complaints about the truck. Parasitic draw is a common problem with a lot of brands today. My aunt has to carry a jump starter in her subaru because her battery has left her stranded more than once. I drive my Ranger mostly on weekends and drive my car to commute during the week. I have the Ctek charger and connect it to the Ranger on Sunday night and swap it over to the car on Thursday night. No issues with either so far.

I made it a sticky yesterday. I figured there's been so many threads regarding this it'll be easy to find for anyone who searches later..

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[AzScorpion]

Is there a strong reason for having this unit mounted to the vehicle with the plug-in outside.

Why not just wire the the charging leads to ground and the battery, mount an exterior socket like the one shown, and have the charging unit remain outside of the vehicle, sitting on a work bench, plugged into a baseboard receptacle, with leads from the unit running to that exterior socket?

Heat, dust, water, or finding a good location for the unit wouldn’t be an issue.

Or, maybe it’s too early, I’m missing something, and I need another coffee. ?

That's what I did but added a longer lead for the quick connect. I wasn't sure if the Ctek would survive being under my hood in this heat and all the bouncing around when off road.

 

[Bsthroop]

Is there a strong reason for having this unit mounted to the vehicle with the plug-in outside.

Why not just wire the the charging leads to ground and the battery, mount an exterior socket like the one shown, and have the charging unit remain outside of the vehicle, sitting on a work bench, plugged into a baseboard receptacle, with leads from the unit running to that exterior socket?

Heat, dust, water, or finding a good location for the unit wouldn’t be an issue.

Or, maybe it’s too early, I’m missing something, and I need another coffee. ?

I think it's personal preference. I prefer the watertight receptacle I have(110) which seals well and not have a dangling cable in the grille. There may be a similar low voltage sealed/mountable plug but I already had the onboard type charger from my RV and had the outlet with a timer I installed at the truck's drivers corner in the garage that I used for my previous Ram diesel for the block heater.

This set up also is totally portable so with an extension cord I can charge in RV parks or at the cabin.

 

[airline tech]

Here: From Service Manual - Charging System Operation - To add to this thread.
The only thing I cannot find is any documentation in the service manual on the 70% State of Charge. (Setting) The only place I have seen that number is in ForScan, plus also looking Specific documentation on Load Shed, Sleep Etc. Mainly what exactly other than Sync 3, gets dumped.
As other owners who experience issues with doors (unlocking) and any other items that starts to give issues in proper operation when battery issues arise. I am finding the Service Manual to be vague on details.

This is what we need in this sticky, a full detailed description on this system, like where can you find what activates Deep Sleep Mode (In Detail), not just an App telling you, I have not owned or worked on this type of system yet and want to know exactly what to do (IF) I go out to my truck, and it won't start, then 10 or 20 minutes later - it starts no problem, like it never happened - as many other posters have experienced, this is my FRUSTRATION with the system as of this writing and the EXACT DETAILED information on this type of scenario is hard to find. I think this is why there are soooo many posts on this subject

I plan on doing so digging

 

[Trigganometry]

With my CTEK charger I got the extension cord for it and then mounted this on the under the grill in the opening with nothing in it until I put a Putco in there. Has a dust cap so always ready to go.

All the info for this connector is here. https://www.ranger5g.com/forum/threads/quick-change-external-battery-connector.18485/

 

[dtech]

I think Ford missed the boat here, my wife's 2021 Nissan Rogue with all the same equipment except ASS does not have these electrical issues. Ford needs to do a better job of managing shut down current draw and charging capacity.

The current draws are at odds with battery longevity and Ford's charging capacity algorithm, would appear it's designed with the assumption everyone will use ASS, if the system was really smart it would determine whether ASS is used and change the charging algorithm. I don't see much value in the BMS and disconnected it and the battery is charged to higher capacity.
I would be interested in seeing the figures on how much Ford has paid in battery warranty claims.

 

[Russd]

Who knew to hook it up this way? Thanks for the video. Luckily and accidentally, I have my Solar charger hooked up correctly.

 

[Bsthroop]

Here: From Service Manual - Charging System Operation - To add to this thread.
The only thing I cannot find is any documentation in the service manual on the 70% State of Charge. (Setting) The only place I have seen that number is in ForScan, plus also looking Specific documentation on Load Shed, Sleep Etc. Mainly what exactly other than Sync 3, gets dumped.
As other owners who experience issues with doors (unlocking) and any other items that starts to give issues in proper operation when battery issues arise. I am finding the Service Manual to be vague on details.

This is what we need in this sticky, a full detailed description on this system, like where can you find what activates Deep Sleep Mode (In Detail), not just an App telling you, I have not owned or worked on this type of system yet and want to know exactly what to do (IF) I go out to my truck, and it won't start, then 10 or 20 minutes later - it starts no problem, like it never happened - as many other posters have experienced, this is my FRUSTRATION with the system as of this writing and the EXACT DETAILED information on this type of scenario is hard to find. I think this is why there are soooo many posts on this subject

I plan on doing so digging

Any idea now to reset as it describes when you replace the battery? The owners manual does not mention the reset under replacing the battery. so does it reset when power is disconnected?

 

[airline tech]

Any idea now to reset as it describes when you replace the battery? The owners manual does not mention the reset under replacing the battery. so does it reset when power is disconnected?

With a Scan Tool, I think (not sure) ForScan can do it

 

[RangerBill]

Any idea now to reset as it describes when you replace the battery? The owners manual does not mention the reset under replacing the battery. so does it reset when power is disconnected?

Someone posted this site:


You should only reset the BMS when replacing the battery.
(Try not to get too dizzy while watching this video as he whips the camera around quite a bit).

 

[Dahveed]

Someone posted this site:


You should only reset the BMS when replacing the battery.
(Try not to get too dizzy while watching this video as he whips the camera around quite a bit).

Yep, this combo does indeed work. I used it on my Ranger a few weeks ago when I replaced my battery. Forscan reported zero days in service for the battery after I performed the procedure.

 

[Bsthroop]

Someone posted this site:


You should only reset the BMS when replacing the battery.
(Try not to get too dizzy while watching this video as he whips the camera around quite a bit).

Thanks that worked great, now to get some Dramamine.

 

[Caliope]

I have been fighting with this on my '19 Ranger (9k miles). The battery was replaced after a year. It is back at the dealership again for this issue, because charging the battery wasn't solving the issue and I was getting the notice he showed in the video when I got in to start the truck.

Now my '22 Bronco Sport (3k miles) is saying that the vehicle is charging as the reason the ASS is not working. It was fine until we had our first cold spell 2 weeks ago. Put the charger on it tonight and the charger said the battery was @ 57%. So, apparently I am going to have to invest in a second trickle charger. The BS does have post type bolt on the negative battery terminal wire body ground, making easy to clamp to.

 

[Bsthroop]

I have been fighting with this on my '19 Ranger (9k miles). The battery was replaced after a year. It is back at the dealership again for this issue, because charging the battery wasn't solving the issue and I was getting the notice he showed in the video when I got in to start the truck.

Now my '22 Bronco Sport (3k miles) is saying that the vehicle is charging as the reason the ASS is not working. It was fine until we had our first cold spell 2 weeks ago. Put the charger on it tonight and the charger said the battery was @ 57%. So, apparently I am going to have to invest in a second trickle charger. The BS does have post type bolt on the negative battery terminal wire body ground, making easy to clamp to.

Based on your mileage you likely don't drive enough to keep it charged. Charger should help, just make sure the charger ground is on the chassis side of the current sensor. My understanding is that even if the battery is charged, if the current sensor was not recording the charge it will continue to give you warnings.

 

[Caliope]

Yea, I don't drive much. A previous thread on this site clued me into the proper charging method. I connect the the negative wire to the bolt that grounds the negative on the battery to the body on the inner fender to the right of the battery.

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