Ford BMS issues, research, testing, and solution results

[SilverPigeon]

A day later; no change in circumstances. Battery disconnect did not alter my modified BCM charging settings. Up 6% and 0.3V; is the BMS still learning? . Will see what tomorrow brings.

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[SilverPigeon]

Another day, another 2%. Same conditions. I'll get to drive the truck on Friday when I head off for Clay shooting, then back on the charger Sunday night. I'll check I it before leaving, arriving, Saturday morning, Sunday morning, leaving and arrival at home.

 

[Ricksc]

Ok I need some help. Charge battery all day with monitor on it. Reaches 95% SOC. Yes I know not 100%. Put in truck it says 60% SOC even after BMS reset. Took like 3 times to get to BMS reset. Kept saying SOC low.

 

[Ricksc]

Here is battery monitor showing it charged

 

[SilverPigeon]

Ok I need some help. Charge battery all day with monitor on it. Reaches 95% SOC. Yes I know not 100%. Put in truck it says 60% SOC even after BMS reset...

Exactly what happened to me as soon as I replaced the BMS and reset. As above, charged and tested 100%, truck reported 69%. Been going up gradually without a driving cycle. Common aspects: new BMS? BCM update done? Original H6 battery?

 

[Ricksc]

No not H6. I upgraded 2 years ago to H7. Yes tried new BMS module. Think I will go back to old BMS module. Will try that tomorrow.

 

[Ricksc]

Going to talk with my buddy that’s a ford mechanic tomorrow. Will see what he has to say.

 

[Ricksc]

Exactly what happened to me as soon as I replaced the BMS and reset. As above, charged and tested 100%, truck reported 69%. Been going up gradually without a driving cycle. Common aspects: new BMS? BCM update done? Original H6 battery?

Talked to my buddy he said to try using computer to reset BMS. He asked how I was doing told him 5 times high beam 3 times brakes, he looked at me like I was crazy. Said I have never heard of that.

 

[SilverPigeon]

Completely valid way to reset the BMS.

 

[Ricksc]

Today I am going to put back the old BMS and see what happens

 

[Porpoise Hork]

It'd be an interesting test to compare the behavior of the two. If it has the same behavior then there's something going on with the BCM and how it's reporting the battery SOC. When you swap it out use Forscan to reset the BMS and i'd give it a full 8 hours of key off for it to do it's thing.

 

[Ricksc]

Heading to auto store tomorrow. Hoping for new battery 3 year free replacement only been 2 we shall see. Put old BMS in and I get low voltage SOC. I put battery monitor on battery and it’s at 54% after full charge yesterday. Maybe it’s time for a super duty

 

[SilverPigeon]

Effectively no change today; I'm now of the opinion that the BMS also needs to see a good engine run to properly figure out where the battery really is. Can't do that until Friday; will report back then.

On a positive note, it seems I'm no longer getting large drops in SOC , but the weekend will tell.

 

[Ricksc]

Beginning to wonder if all the ways the say to reset BMS really work. Truck parked for 9 hours too no change in BMS. When new battery will add it to charger to make sure it’s really 100% then put in truck then with forscan reset BMS

 

[Snakebitten]

Heading to auto store tomorrow. Hoping for new battery 3 year free replacement only been 2 we shall see. Put old BMS in and I get low voltage SOC. I put battery monitor on battery and it’s at 54% after full charge yesterday. Maybe it’s time for a super duty

My brand new F350 came with a plain old lead acid battery. Not an AGM.

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