A Dummy Discovers the Amazing Benefits of a B.M.S. Reset!

[Mavster Mechanic]

Me.

I had totally forgotten about the BMS reset. Silly me, been wondering why the charging system on my Maverick never seemed to charge the battery past 12.1 / 12.2VDC regardless on how much I drove. A 120 mile round trip, which I expected to fully charge the battery did virtually nothing. Stuck on the low 12V. So, hook up my Noco Genius 5 (Glad at least my charger is a genius ) After 5 hours i am getting the same readings. WTF????

Well, that is when it dawned on me about doing a reset. Off to YT to refresh my failing memory. It only took me about 5 tries before I could get the BATT icon to blink. The process is as straight forward as it can possibly be but leave it to me to somehow frig it up 4 times.

Now after a short trip the battery voltage measured at the 12V power outlet with one of those combo USB / voltmeter now reads 12.5 - 12.6. Engine off, all interior and cargo light off. Even my A.S.S. is now working again after over a year.

Moral of the story, don't be a dummy like me and reset your BMS from time to time. It will make your Maverick much happier and put a lot less stress in your life.

FWIW

I left my 12v disconnected overnight.
12 hours. Less may have worked.

It reset everything upon reconnecting.

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[Bob The Builder]

I'm guessing there is a difference between reset and relearn, but I am not sure. Sounds like reset does a reset of battery data and tells the battery the current charge is the preferred charge level, is that correct? And if the relearn is different, how so? I routinely leave my truck locked overnight and/or for days, so the truck is "relearning" the battery state. If I don't throw it on the charger and don't drive it enough, is it "relearning" a slowly degrading battery state (between driving/charging days) which is making the battery go bad faster?

Yep. Valid points.

 

[SafetyGuy]

I'm guessing there is a difference between reset and relearn, but I am not sure. Sounds like reset does a reset of battery data and tells the battery the current charge is the preferred charge level, is that correct? And if the relearn is different, how so? I routinely leave my truck locked overnight and/or for days, so the truck is "relearning" the battery state. If I don't throw it on the charger and don't drive it enough, is it "relearning" a slowly degrading battery state (between driving/charging days) which is making the battery go bad faster?

Valid questions, Prickly Pear.

I know I am guilty of using the wrong names, so let's stick to what the manual says to do.

BMS reset to me sounds like when you put a new battery into a truck.

Relearn to me means just charging the battery and then locking the truck up for 9-10 hours.

Use our assistance with the manual (relevent pages added below!), is my recommendation.

It is my thought if the truck is locked long enough and enough times-the truck will learn to charge the battery inadequately.

Have a great day,

Andy

 

[Prickly Pear]

It would be ironic if the relearn feature was part of why our batteries are not getting charged enough!

 

[SafetyGuy]

It would be ironic if the relearn feature was part of why our batteries are not getting charged enough!

I know! You nailed my preventive thought process.

And I overcome this by every month or two just doing the battery full charge with my external smart charger (good for the batteries health), and then letting ithe truck sit locked up for the 9-10 hours!

Andy

 

[Meeka]

I know! You nailed my preventive thought process.

And I overcome this by every month or two just doing the battery full charge with my external smart charger (good for the batteries health), and then letting ithe truck sit locked up for the 9-10 hours!

Andy

I do the same thing with the battery in my Camaro when I park it for the winter, it’s out and down stairs with my riding mower battery. Seems to work so I’m not messing with it.

 

[Mavster Mechanic]

It would be ironic if the relearn feature was part of why our batteries are not getting charged enough!

People doing it incorrectly makes things worse, not better.

 

[SafetyGuy]

I do the same thing with the battery in my Camaro when I park it for the winter, it’s out and down stairs with my riding mower battery. Seems to work so I’m not messing with it.

Yes, definitely a good way to store your batteries over the winter...all changed up and put away.

I do think they can drop a little bit of charge every month, but nothing like sitting in a vehicle and draining.

I know my camper van has 2 deep cycle batteries now, the 12 volt deep cycle kicker battery to connect the Li storage batteries (essentially the same job as our truck battery), and the 12 volt battery to start the 3.6 liter gas engine.

The starter battery failed just after we bought the van (parasitic drain and sitting in a lot over winter).

So I went to Canadian Tire and bought the biggest AGM battery that fit our Ram Van.

For winter I hook up 2 smart chargers as the Li batteries don't need charging and am all done till spring (van sits in our garage, not outside).

When I want to charge my Maverick I just grab the larger of the 2 chargers and transfer it over, then back again when done.

All our batteries are happy.

Have a good one,

Andy

 

[HeyBales]

I'm guessing there is a difference between reset and relearn, but I am not sure. Sounds like reset does a reset of battery data and tells the battery the current charge is the preferred charge level, is that correct? And if the relearn is different, how so? I routinely leave my truck locked overnight and/or for days, so the truck is "relearning" the battery state. If I don't throw it on the charger and don't drive it enough, is it "relearning" a slowly degrading battery state (between driving/charging days) which is making the battery go bad faster?

Reset for sure zero's out several points of tracking data that can be seen, probably a few more that can't be seen. Like since it's a new battery, maybe last resistance reading, and last Voltage for full battery.

The Relearn is learning what some values are that would normally be known and entered for a battery, that effects how it tracks and thinks measurements are - like battery Ah being a big one.
That process shuts off some electronic processes as manual says - like to do what other systems do - measure a known drain amount for a chunk of time, discern how far the battery dropped, and decide how big it must be.

Now the Ah's counted for charging and discharging mean something.
You can see what would be done, by looking at solar and charging batteries when the user would normally input all the required info - then the system merely counts to track SOC%, and it knows where full is.

I think I see the evidence in our systems, as long as you don't do a BMS Reset on a old discharged battery saying it's new - the Relearn figures it out.
It's not learning new lows or max levels, it's seeing how bad resistance is, age, recalculating the SOC%.
I've seen days in a row with low voltage 11.9, but it's declaring 60+ SOC%.
And then a night a relearn probably happened, the next day it's still 11.9, but 53%.
The 60% was worse - it seemed to go to float charging amps at 60.
But starting at 53% it's inspired - high Amp charging to and beyond 60 - I just saw that happen this last week.

I'm sure there is some original value stored from when it was told new battery, and the regular Relearns that occur are not setting a low point for charging, but rather resistance, and correcting the SOC% value. I've seen it correctly go up to - after an external charge.

It's also why I'm convinced I'm dealing with bad sensor for reading amps - if it thought Ah in equaled Ah out, as mine currently is, I wouldn't be losing Voltage slowly but surely, it wouldn't be recalcing a lower SOC% from time to time.
But not everone has this issue, I drive enough.

 

[HeyBales]

So what happened to cause my battery to not charge above 12.2 Volts after a long drive. The power point VM registered 14.9 - 15.1V whenever i looked at it on the drive, yet when I shut the engine off it would plummet to 12.2 give or take. I would really rather not live with that as i consider that too low for my dash cam when parked away from home. Low voltage cutoff on the cam is around 12.1V. The BMS reset gave me 12.5V back which is more like it.

Battery was replaced under warranty two years ago when the truck was 7 months old and the truck currently has 9.950 on the clock.

It just struck me - I'm thinking of yours like a hybrid system pre-25MY.

Your manual for specs on battery says to use the same size as OEM, or have dealer correct the figures regarding it if not.

If your Voltage reading at power port goes to 12.2 after driving, which means charging, then that is really an invalid but inflated figure - that means it's even worse than that.

Doesn't matter if it reads high Volts - it's being fed low Amps.
Your battery is probably already sulfated - and the system knows it, and doesn't think it can charge higher.

The problem with charging an already bad battery with high resistance, it may mean a cell is going bad faster than the others. Charge at a decent rate, you'll be overcharging one, undercharging the others. So you attempt an undercharge to not damage the bad one faster.

I'm betting the Reset erased some values regarding that. Were they right or wrong values gained during Relearn processes?
Time will tell.


https://www.batteryuniversity.com/article/bu-403-charging-lead-acid

Aging batteries pose a challenge when setting the float charge voltage because each cell has its own unique condition. Connected in a string, all cells receive the same charge current and controlling individual cell voltages as each reaches full capacity is almost impossible. Weak cells may go into overcharge while strong cells remain in a starved state. A float current that is too high for the faded cell might sulfate the strong neighbor due to undercharge. Cell-balancing devices are available compensate for the differences in voltages caused by cell imbalance.

Ripple voltage also causes a problem with large stationary batteries. A voltage peak constitutes an overcharge, causing hydrogen evolution, while the valley induces a brief discharge that creates a starved state resulting in electrolyte depletion. Manufacturers limit the ripple on the charge voltage to 5 percent.

 

[ice445]

Good day, @ice445

I think you are referring to the process where in the manual you carry out a full new battery reset...with the whole flashing lights etc process? (For when the battery is actually replaced)

Yes, if that is what you are saying, I believe you are correct.

As for what we have been doing here is resetting the battery to the point where the battery is being charged as best as possible by first externally charging the battery and then letting the truck put on a couple coats of "think", and resets its own internal charge profile.

It is my thought that this shouldn't negatively impact the trucks process as to battery age...of course I could be wrong. So, I will continue today thinking about it, maybe re-read the process again in the manual to check and see!

Thanks, and have a great day,

Andy

I see, I thought he was actually doing the reset. Letting it relearn is fine. One problem you will run into no matter what though is that the target soc is only 80%. Why Ford chose to do this, I cant say. You have to change it in forscan or live with the battery always ending up around that level of charge. Or put it on a tender I guess lol

 

[HeyBales]

I see, I thought he was actually doing the reset. Letting it relearn is fine. One problem you will run into no matter what though is that the target soc is only 80%. Why Ford chose to do this, I cant say. You have to change it in forscan or live with the battery always ending up around that level of charge. Or put it on a tender I guess lol

This is incorrect with target SOC of 80%.
Not what the PID is called.

This is when it goes to float charge - if you have a scanner you'll see it still charges above 80%.

Also, that is 80% out of 85% fully charged Ford SOC scale. At least pre-25MY.
Not your typical AGM battery SOC scale of 80%.
85% is 12.8 V - after the system has done a relearn.

Many people have done that setting change - changes nothing when they watch scanner data.
They still don't get a SOC above 85%.
Some have started a drive after a recharge the prior day with it higher - and it nosedives back down.

 

[Cherokee]

I know! You nailed my preventive thought process.

And I overcome this by every month or two just doing the battery full charge with my external smart charger (good for the batteries health), and then letting ithe truck sit locked up for the 9-10 hours!
Andy

This Is The Way
:’P

 

[Aherpa]

I must be doing something right (wrong?) because I don't do anything to the battery and the truck works works fine. I don't charge the battery, I don't lock the truck for 8-10 hours, nor do I have to flash my high beams hit the brakes and sacrifice a goat to the goddess Electra.
Good little truck, keep behaving yourself . . .

 

[ice445]

This is incorrect with target SOC of 80%.
Not what the PID is called.

This is when it goes to float charge - if you have a scanner you'll see it still charges above 80%.

Also, that is 80% out of 85% fully charged Ford SOC scale. At least pre-25MY.
Not your typical AGM battery SOC scale of 80%.
85% is 12.8 V - after the system has done a relearn.

Many people have done that setting change - changes nothing when they watch scanner data.
They still don't get a SOC above 85%.
Some have started a drive after a recharge the prior day with it higher - and it nosedives back down.

What is it called then? I drive every day and every time ive looked at that value, its always somewhere in the low to mid 70% range. But yeah, that makes sense it just goes to a float charge at that point. Isn't an actually fully charged agm read at 13.4v though?

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