BCM Battery charging rate >14.7 volts and aftermarket batteries

[Skylarking]

Any of the exide and century/yuasa offerings e.g. DIN65LHX MF & Exide extreme XDIN55HMF

They are not EFB as far as I can tell.

Personally I am using ACDelco S57090AGM

Century lists their ultra high performance battery as a maintenance free battery on their web site with not much more detail (unless you dig throug( their website and find more info?). Exide lists their extreme battery as a sealed maintenance free calcium battery on their website.

ACDelco do provide some more info that compares SMF, Calcium, EFB but what the real differences are isn’t so clean for owners.

I also doubt the stock batteries are EFB. ACdelco advertise stand alone EFB batteries. https://acdelco.com.au/our-range/batteries/
They certainly are calcium though. Stock battery i S56838 (premium SMF as per above linked brochure)

Yes that seems to be the case but I haven’t been able to get clear information on the exact difference between SMF calcium batteries and EFB from a charging perspective (though I’ve not spent huge time looking).

Sadly manufacturers seem to bury their battery specs and correct charging strategies in not easy to find places. Such shouldn’t be difficult to find but that seems to be the case.

It wouldn’t surprise me if some of the difference may just just come down to marketing speak. It also wouldn‘t surprise me if some brands put max voltage warnings on their batteries to scare people towards their more expensive models… After all, upsell rules

In any case, Calcium batteries supposedly can handle a little more voltage than the old flooded batteries which needed to be periodically topped up with distilled water. But then from the Century tech section of their web site we get:

Auxiliary Charge Voltage by Battery Type​

​

Type​	Absorption Charging​	Float Charging​
Flooded (Maintainable / SMF)​	14.4 to 14.8V​	13.2 to 13.5V*​
AGM (Absorbed Glass Mat)​	14.6 to 14.8V​	13.6 to 13.8V​
Gel Electrolyte​	14.2 to 14.4V​	13.6 to 13.8V​

*We do not recommend to float charge flooded Sealed Maintenance Free (calcium) batteries due to risk of drying out of the electrolyte.​

​

The recommended temperature during charging is 25°C. Charging must be paused if the battery reaches 50°C.​

So, I’d gel electrolyte an EFB or not. And if we listen to Century, don’t drive in >40C temps as you will charge the battery at too high a voltage (unlessGM/Holden adjust voltage based on battery temp)

Who to believe?

What ever the case, if a seller states a particular battery is suitable for your car, if you are concerned, get him to put that fact on the receipt. When/if it fails prematurely, you’ve got some comeback against the seller of the battery isn’t suited t9 your vehicles charging circuit…

 

[stooge]

(unlessGM/Holden adjust voltage based on battery temp)

one of the conditions that changes the charge voltage is intake air temp and/or engine/coolant temp.

we found this out when we made a egr delete mod for the colorados using the IAT sensor, the charge voltage went up to 15+ because we had the IAT reading -3deg.
my workaround was to delay the egr mod until the engine/coolant temp got above 70deg and doing this normalized the charging system even with the IAT reading -3deg

that was in a vehicle with the battery in the engine bay though, i am not sure if it still applies to the ve/vf with the battery in the boot.

 

[Skylarking]

one of the conditions that changes the charge voltage is intake air temp and/or engine/coolant temp.

we found this out when we made a egr delete mod for the colorados using the IAT sensor, the charge voltage went up to 15+ because we had the IAT reading -3deg.
my workaround was to delay the egr mod until the engine/coolant temp got above 70deg and doing this normalized the charging system even with the IAT reading -3deg

that was in a vehicle with the battery in the engine bay though, i am not sure if it still applies to the ve/vf with the battery in the boot.

Interesting but using intake air temp is a little flawed as it assumes the battery is the same temp as the incoming airstream. I’d thing if the battery is in the engine bay, it’d be much hotter…

With the VF battery in the boot, if they use the incoming air temp, that could be a good approximation of the battery. But really. In the VF if they can put a current sensor at the battery, why not a temp sensor as well?

We’ve seen what approximations can cause in the HVAC when Holden cheaper out and removed many VE interior temp sensors and used less sensors and an approximating algorithms instead where the VF = HVAC by Dr. Jekyll & Mr. Hyde

I’m not a fan of approximations and it’s not as if doing it correctly would cost huge money…

 

[dassaur]

one of the conditions that changes the charge voltage is intake air temp and/or engine/coolant temp.

we found this out when we made a egr delete mod for the colorados using the IAT sensor, the charge voltage went up to 15+ because we had the IAT reading -3deg.
my workaround was to delay the egr mod until the engine/coolant temp got above 70deg and doing this normalized the charging system even with the IAT reading -3deg

that was in a vehicle with the battery in the engine bay though, i am not sure if it still applies to the ve/vf with the battery in the boot.

From my obs it doesnt seem to coincide with temp changes although it would be an interesting experiment. I might see if I can set up a graph with IAT and voltage for my next drive.

 

[stooge]

From my obs it doesnt seem to coincide with temp changes although it would be an interesting experiment. I might see if I can set up a graph with IAT and voltage for my next drive.

Modify the iat temp to -3 on a colorado and you will see cooked batteries, it happened to a few people and others reported 15+v all the time.

The charge voltage thrown at a battery is dependent on temperature of the battery, if the battery is too hot and you pump a high voltage charge into it they have problems.
Too cold and not enough charge then they dont seem to charge enough.

I dont know what sensors the vf uses to estimate battery temp but i suspect iat or cabin temp will give the system a good estimate of what the battery temp is.

 

[dassaur]

Modify the iat temp to -3 on a colorado and you will see cooked batteries, it happened to a few people and others reported 15+v all the time.

The charge voltage thrown at a battery is dependent on temperature of the battery, if the battery is too hot and you pump a high voltage charge into it they have problems.
Too cold and not enough charge then they dont seem to charge enough.

I dont know what sensors the vf uses to estimate battery temp but i suspect iat or cabin temp will give the system a good estimate of what the battery temp is.

Sorry I didnt mean to doubt you, I meant the charging rate in the VF. I am keen to throw on some data so hopefully this arvo when I get the kids I can set up a graph.

 

[Skylarking]

From the service manual:

Electrical Power Management Overview​

The battery condition is estimated during ignition-off and during ignition-on. During ignition-off the state-of-charge of the battery is determined by measuring the open-circuit voltage. The state-of-charge is a function of the acid concentration and the internal resistance of the battery, and is estimated by reading the battery open circuit voltage when the battery has been at rest for several hours.​

The state-of-charge can be used as a diagnostic tool to tell the customer or the dealer the condition of the battery. Throughout ignition-on, the algorithm continuously estimates state-of -charge based on adjusted net amp hours, battery capacity, initial state-of-charge, and temperature.​

While running, the battery degree of discharge is primarily determined by a battery current sensor, which is integrated to obtain net amp hours.​

In addition, the electrical power management function is designed to perform regulated voltage control to improve battery state-of-charge, battery life, and fuel economy. This is accomplished by using knowledge of the battery state-of-charge and temperature to set the charging voltage to an optimum battery voltage level for recharging without detriment to battery life.​

Charging System Operation​

Voltage Reduction Mode
The BCM will enter Voltage Reduction Mode when the calculated ambient air temperature is above 0°C (32°F). The calculated battery current is less than 1 ampere and greater than −7 amperes, and the generator field duty cycle is less than 99 percent. Its targeted generator output voltage is 12.9 V. The BCM will exit this mode once the criteria are met for Charge Mode.​

So yep, the VF charging system has some smarts to it and uses air temperature and other things to determine the charge voltage.

If interested in the deep dive, it starts on page 3906 of the workshop manual

 

[dassaur]

nice find. Got some light reading
I wonder what air temp sensor.

 

[Skylarking]

nice find. Got some light reading
I wonder what air temp sensor.

Its not mentioned within the mentioned within the Battery Description and Operation section.

That section also states:

Charge Mode​

The BCM will enter Charge Mode when ever one of the following conditions are met.​

• The wipers are ON for than 3 seconds.​

• GMLAN (Climate Control Voltage Boost Mode Request) is true, as sensed by the HVAC control head. High speed cooling fan, rear defogger and HVAC high speed blower operation can cause the BCM to enter the Charge Mode.​

• The estimated battery temperature is less than 0°C (32°F).​

• Battery State of Charge is less than 80 percent.​

• Vehicle speed is greater than 145 km/h (90 mph)​

• Current sensor fault exists.​

• System voltage was determined to be below 12.56 V​

When any one of these conditions is met, the system will set targeted generator output voltage to a charging voltage between 13.9–15.5 V, depending on the battery state of charge and estimated battery temperature.​

Odd that if the current sensor is faulty the system always goes into charge mode. But there isn’t enough logic defined to know how SOC is determined and what impact a faulty current sensor is may have in such estimations… Does that mean the battery charge voltage may be too high in some cases cause the SOC is wrong… and will such SOC errors kill your battery as a result? Logic as stated in yje workshop manual is rather vague…

You may be interested in Battery Charging and Parasitic load testing on page 3942 and 3944 respectively…. welcome to the rabbit hole that is the VF workshop manual