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

[SafetyGuy]

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 . . .

Yes, it is nice to have a vehicle that isnt giving you problems.

I am in the same boat as I have had no issues or indications of problems with my truck or its battery.

I guess I am one of those people that prefers taking simple preventive measures instead of waiting for an issue pop up...when they do it always seems to be at the worst time.

Have a great day,

Andy

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[SafetyGuy]

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?

Here is a site I went to, to confirm AGM charge information.

https://batterytools.net/agm-battery-charging-voltage-chart/

Here are several screenshots I took to post here for quick reference.

Andy

 

[HeyBales]

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?

That would be a low charging voltage when it's fuller.
But a cold reading - sounds rather high.

You may already have an undercharged battery, and it's decided not safe to attempt for full charge unless you have a reeeaaaallllyyy long trip. Think battery charger float charge time - because that's what it's doing. That's what the problem is for many of us - for probably reasons of safety and mileage - it drops to float charge waaayyy too soon.

If that 70% is from external monitor?
If that 70% is from an OBD scanner and truck data - add the Amp & Volt readings.
There is a better Bat_Current PID than below that says for battery 2 - it'll display the .xx not just whole numbers.

 

[HeyBales]

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 . . .

Some really don't have issues. Some have reported being in cold winter areas and not driving much!

What's your average typical drive time for most days of the week?
Distance doesn't matter, time does.

The battery saving functions are exactly so the truck starts - and thereafter works fine.
Ever noticed how soon your cabin light turns off if you sat there after removing key on turnoff?
Do you have anything plugged into your powerport to notice if it's still powered up - like when you open the door to get out?

 

[UTAlumnus]

My GLI can do it too.

Honestly its so backwards how the HVAC gets locked to touchscreens but to do any sort of maintenance you need OBD II readers and esoteric pedal combos. All the maintenance minders and modes should be accessible via the center screen so you can do re learns or resets without any external tools, like how 99% of PCs operate.

While I am on my soapbox, these screens should be able to display error codes too. Printers and PCs can display error codes and suggested fixes and have done so for 15+ years. Why cant my car display an oxygen sensor error instead of triggering the CEL and telling me nothing? The Buick Riviera could do this in 1986! How have we gone backwards?

Then they couldn't charge $$$ to tell you what the codes mean.

 

[ice445]

That would be a low charging voltage when it's fuller.
But a cold reading - sounds rather high.

You may already have an undercharged battery, and it's decided not safe to attempt for full charge unless you have a reeeaaaallllyyy long trip. Think battery charger float charge time - because that's what it's doing. That's what the problem is for many of us - for probably reasons of safety and mileage - it drops to float charge waaayyy too soon.

If that 70% is from external monitor?
If that 70% is from an OBD scanner and truck data - add the Amp & Volt readings.
There is a better Bat_Current PID than below that says for battery 2 - it'll display the .xx not just whole numbers.

I use forscan lite like that. I think its that first PID. I read it from the BCM.

Given my truck was a leftover 24 and sat for several months its possible my battery just degraded somewhat.

 

[tiktokbrainrot]

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?

Only if you just turned the truck off. Once it has sat overnight it should read 12.8V.

Honestly these trucks would really benefit from using lithium iron phosphate batteries instead of lead acid. They love sitting at 70% charge and dont mind the million little vampire drains.

 

[HeyBales]

I use forscan lite like that. I think its that first PID. I read it from the BCM.

Given my truck was a leftover 24 and sat for several months its possible my battery just degraded somewhat.

For sure.
My OEM battery made in Oct '23, truck 3/24, and activated 4/8/24 - when the BMS system would have started doing anything.
Which in this case, was watching a battery degrade worse until I got it 4/23.
Unless the dealership did a charge up. I'm doubtful.
No wonder it was too late by Sep when I saw many having issues, and looked at mine, and attempted a recharge/reset/relearn - twice!
Too late to do any good.
But that little guy made it until July '25, max battery saver mode, never a deep sleep mode though.

You'll like those 2 extra PID's, also from the BCM.
If you can get Forscan Lite to connect to show you a pre-start Voltage, even better.
Let's you see how that can remain almost the same morning to morning, but the SOC% changes. And that effects the Amp current reading.

That extra group of 4 PID's about cumulative charge/discharge - interesting too.
I'd be curious how yours add up.

 

[Bob The Builder]

Here is a site I went to, to confirm AGM charge information.

https://batterytools.net/agm-battery-charging-voltage-chart/

Here are several screenshots I took to post here for quick reference.

Andy

These trucks are charging the AGM right at the max! At least mine is. Hovers right around 15 V. Never higher than 15.1 / 15.2.

My battery spent all winter around 11.9 - 12.1. No matter how much driving I did. Always started and ran great. NO AS/S though. The BMS got it up to 12.5. I current have the truck on trickle charge overnight. No more BMS resets. I hope to fully charge the battery and then give the truck a nice quiet nap after that.

 

[HeyBales]

These trucks are charging the AGM right at the max! At least mine is. Hovers right around 15 V. Never higher than 15.1 / 15.2.

My battery spent all winter around 11.9 - 12.1. No matter how much driving I did. Always started and ran great. NO AS/S though. The BMS got it up to 12.5. I current have the truck on trickle charge overnight. No more BMS resets. I hope to fully charge the battery and then give the truck a nice quiet nap after that.

Hopefully it doesn't dream of running the AC.
Maybe just the turbo.

When you take a peek at it sleeping - see if the tires are jerking in and out like it's running.

 

[ice445]

Only if you just turned the truck off. Once it has sat overnight it should read 12.8V.

Honestly these trucks would really benefit from using lithium iron phosphate batteries instead of lead acid. They love sitting at 70% charge and dont mind the million little vampire drains.

I dont think ive ever seen above 12.5 on mine, and I have auto start stop and the TCU disabled, lol.

For sure.
My OEM battery made in Oct '23, truck 3/24, and activated 4/8/24 - when the BMS system would have started doing anything.
Which in this case, was watching a battery degrade worse until I got it 4/23.
Unless the dealership did a charge up. I'm doubtful.
No wonder it was too late by Sep when I saw many having issues, and looked at mine, and attempted a recharge/reset/relearn - twice!
Too late to do any good.
But that little guy made it until July '25, max battery saver mode, never a deep sleep mode though.

You'll like those 2 extra PID's, also from the BCM.
If you can get Forscan Lite to connect to show you a pre-start Voltage, even better.
Let's you see how that can remain almost the same morning to morning, but the SOC% changes. And that effects the Amp current reading.

That extra group of 4 PID's about cumulative charge/discharge - interesting too.
I'd be curious how yours add up.

Ill definitely take a look. Its probably just going to come down to the battery though. Would explain the occasional weird glitches I get, lol

 

[Bob The Builder]

Hopefully it doesn't dream of running the AC.
Maybe just the turbo.

When you take a peek at it sleeping - see if the tires are jerking in and out like it's running.

Stubby, my Boston Terrier used to run a marathon while out like a light. I'd swear the old boy would wake up more tired then when he fell asleep.

 

[Bob The Builder]

Left the truck on trickle overnight. This morning the Genius reported a full charge. A check of the battery voltage measured at the battery terminals with my Fluke meter reads 12.6V.

Conventional wisdom indicates my battery is at 75-80% SOC. I am assuming the BMS stopped any further charge due to factory programming. I am also assuming the battery is good condition as it was able to accept the maximum SOC permitted by the BMS.

Now the truck is locked and going to sit that way until I need it tomorrow. We'll see how things go from there.

Cheers all and thanx for all the great replies and help. Kudos.

 

[SafetyGuy]

Left the truck on trickle overnight. This morning the Genius reported a full charge. A check of the battery voltage measured at the battery terminals with my Fluke meter reads 12.6V.

Conventional wisdom indicates my battery is at 75-80% SOC. I am assuming the BMS stopped any further charge due to factory programming. I am also assuming the battery is good condition as it was able to accept the maximum SOC permitted by the BMS.

Now the truck is locked and going to sit that way until I need it tomorrow. We'll see how things go from there.

Cheers all and thanx for all the great replies and help. Kudos.

Hello again

I am wondering if your Genius has a de-sulphation ability? The reason I ask is that your battery was charged to a low condition for quite awhile, so running a de-sulphation cycle could be a good idea to further increase your batteries condition even further.

I am glad to hear you have charged it up and are doing the battery relearn where hopefully you will see the battery kept in a higher charge state.

I know I just got my 12v cigarette port voltage indicator recently (my wife got it for me for my birthday) but I highly recommend everyone gets one.

Reason being we do not have any indication anymore on the dash of the battery charging state...and to me that is critical info I look for everytime I drive.

Photo added below, and have a good one. I am looking forward to your next update.

It is so satisfying when we help someone out here!

Andy

 

[Bob The Builder]

Hello again

I am wondering if your Genius has a de-sulphation ability? The reason I ask is that your battery was charged to a low condition for quite awhile, so running a de-sulphation cycle could be a good idea to further increase your batteries condition even further.

I am glad to hear you have charged it up and are doing the battery relearn where hopefully you will see the battery kept in a higher charge state.

I know I just got my 12v cigarette port voltage indicator recently (my wife got it for me for my birthday) but I highly recommend everyone gets one.

Reason being we do not have any indication anymore on the dash of the battery charging state...and to me that is critical info I look for everytime I drive.

Photo added below, and have a good one. I am looking forward to your next update.

It is so satisfying when we help someone out here!

Andy

Thanx!! Yes, it does have a repair mode. Never used it and often wondered how effective it is but will certainly try that in the near future and will report back here on the results.

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