Overriding a "smart" battery management system

[circuitsmith]

Now, a side benefit of LED's, at least in my Subaru, is that it drains the battery at a lower rate when, say, my wife decides to leave an interior light on.

Those little 2-10W incandescent interior lamps are far less efficient than even the 55-65W halogen headlights.
Compared to LED's the difference is enormous.
For instance, the W10W incandescent map light in my Hyundai measures 9.3W at 12V, the LED replacement I picked is slightly brighter and uses 0.6W.

The Great Internet Light Bulb Book, Part I

donklipstein.com

 

[350Rocket]

I replaced the original battery in my previous 2006 Toyota Matrix after 9 years.
It was still working okay, but I didn't trust it for a 10th winter.
Back then I connected the battery to an adjustable power supply overnight every 3 months, set to 14.5V.

I do let it do its thing when I'm driving more than 30 minutes.
On return trip to home I bump the voltage up (with the headlights) for the last 30 minutes.

I read the 4 pages here and realized I didn't know as much as I thought about car batteries. I thought they would be similar to cell phone batteries (which don't like to be fully charged or fully drained often). So I understand the need to keep them fully charged now (and why batteries were lasting so long on older vehicles like my 80s GM's and 90s-early 2000 GM's).

My other thought is how much extra life are we possibly getting from the alternator at the sacrifice of the battery? The alternator on my 05 truck was not rebuildable and cost more than a battery. It also outlasted the first 3 batteries in the truck and could still have been working for the 4th had I know about the "intelligent charging".

 

[circuitsmith]

My other thought is how much extra life are we possibly getting from the alternator at the sacrifice of the battery?

I haven't witnessed a lot of alternator failures, but most of them have been due to worn out brushes.
I don't think alternator output has much to do with brush wear.
The one bearing failure (which happened after brush replacement a few years earlier) I'm sure had no relation to alternator output.
So I'm pretty sure an extra 5 amps or less to keep a battery at 100% won't shorten alternator life, but will boost battery life.

 

[circuitsmith]

I read the 4 pages here and realized I didn't know as much as I thought about car batteries. I thought they would be similar to cell phone batteries (which don't like to be fully charged or fully drained often).

You'll find these interesting:

How to Restore Lead-acid Batteries

Explore lead-acid batteries and what causes corrosion, shedding, electrical short, sulfation, dry-out, acid stratification and surface charge.

batteryuniversity.com

BU-808: How to Prolong Lithium-based Batteries

BU meta description needed...

batteryuniversity.com

 

[Surestick]

With all the "intelligence" in cars it would be easy enough to program in a battery condition monitoring system.
Date is known (user input or from cell phone networks), location is known (onboard GPS), the temperature outside is known, the battery voltage is known, battery health and state of charge should be easy enough to extrapolate, after all a battery tester is basically a big load like, say, starting an engine.
The car should be able to figure out if it's summer (battery state of charge can drop a lot lower without battery damage or no-start) or winter (battery damage due to freezing more likely, no-start more likely) in its location. With a connection to cell phone networks, the car should even have access to local weather forecasts.
- If it's winter or cold weather is expected give the battery as much charge as possible.
- Set a low-battery charge state for summer and winter (obviously summer can drop lower than winter) and put a message on the dash suggesting they charge the battery or the vehicle might fail to start.
- Set a battery health warning letting the driver know the battery capacity is below a certain threshold and they should think about replacing it.

It's a lot less of an inconvenience knowing beforehand that the battery needs attention than finding out the hard way when you have somewhere important to be and your vehicle won't start, or worse, you're stranded somewhere unsafe.

 

[wrcsixeight]

I have a columb counter, which counts amp hours into and out of the battery(s)

Its a very helpful tool, but is very imperfect.

When my original engine computer voltage regulator was controlling my alternator, there were two voltages allowed 99% of the time, 14.9 or 13.7v.

14.9v with an altready fully charged battery was not required, and 13.7v when the deeply cycling battery was still well undercharged was infuriating.

With a digital ammeter and voltmeter counting amperage into and out of the battery, one gets vast experience at how much amperage a battery decides to accept at different states of charge and health and temperature.

For a starting battery none of this is very unimportant
For achieving acceptable lifespan on a deeply cycling battery is it required.

When one is trying to achieve a true 100% state of charge, they will find most everything 'automatic' falls well short of this goal.

When one goes for a manual charging source with adjustable voltage and takes readings with a hydrometer or amperage accepted at absorption voltage, they can see ust how long it actually takes to achieve a true 100% state of charge.

That so many people believe the alternator is some magical physics defying instant battery charger, is no longer surprising, but that so many mechanically apt people have so little idea of how a lead acid battery charges, is disappointing.

80% charged to 100% charged takes no less than 3.5 hours. This 3.5 hours assume the battery is still healthy and being held in teh mid 14 volt range for the entire duration. An older battery or one held at lower voltages takes significantly longer to reach full charge, if it even can.

many modern vehicles voltage regulation intentionally keeps the battery around 80% charged. more than enough to start the engine, even near end of its useful life, but that useful life is a fraction of what it could have been if it had even been kept on average of 95% charged.

I doubt I'd bother with trying to trick/ modify a vehicles voltage regulation if I were not deep cycling a battery, I'd just plug into the grid more often if possible to achieve the true full charge regularly, and even though most smart chargers fall well short of the true 100% state of charge, increaseing the state of charge of any lead acid battery is always a good thing and will help it perform better and last longer.

 

[350Rocket]

With all the "intelligence" in cars it would be easy enough to program in a battery condition monitoring system.
Date is known (user input or from cell phone networks), location is known (onboard GPS), the temperature outside is known, the battery voltage is known, battery health and state of charge should be easy enough to extrapolate, after all a battery tester is basically a big load like, say, starting an engine.
The car should be able to figure out if it's summer (battery state of charge can drop a lot lower without battery damage or no-start) or winter (battery damage due to freezing more likely, no-start more likely) in its location. With a connection to cell phone networks, the car should even have access to local weather forecasts.
- If it's winter or cold weather is expected give the battery as much charge as possible.
- Set a low-battery charge state for summer and winter (obviously summer can drop lower than winter) and put a message on the dash suggesting they charge the battery or the vehicle might fail to start.
- Set a battery health warning letting the driver know the battery capacity is below a certain threshold and they should think about replacing it.

It's a lot less of an inconvenience knowing beforehand that the battery needs attention than finding out the hard way when you have somewhere important to be and your vehicle won't start, or worse, you're stranded somewhere unsafe.

That would be a good idea. The smartest thing I've seen for battery management is the 2013 Silverado at work needed a battery replacement during the short period I drove it before switching back to the 2005....middle of summer, listening to music at lunch with the engine off I got an audible ding and a message on the dash "battery low - start engine now".

 

[circuitsmith]

middle of summer, listening to music at lunch with the engine off I got an audible ding and a message on the dash "battery low - start engine now

Many Hyundai/Kia also have this function, display a warning if the battery voltage falls too low.

 

[Jetronic]

Actually I believe the hyundai kia always show this after a few minutes with the ignition on, regardless of voltage... more like

• don't eat the yellow snow
• don't put nails in the seat cushion
• put diesel in a diesel, gas in gasser
• if you keep playing the radio, you will get a flat battery

 

[urdrwho]

I'm having battery issues with my 2016 Volvo V60 and all this smart battery / smart charging makes me realize that we should tie the hands of engineers. I remember driving in the 1960's we would find a field to have a little party, fire up the radio and have some fun. Unless we were driving some guys car that had a weak battery there was never a problem starting the car to leave.

Now with all this smart technology the computer would start having a fit after 15 minutes. I for one am not impressed!!!!

Does anyone believe that their engine is fully charging their battery? Do these new and improved methods prevent or excel sulfation? So we save one tenth of a MPG but in the process we produce a mountain of batteries that died before their time?

I'm driving a loaner right now, a 2021 Volvo XC60 and with its big touch screen that is needed to digitally adjust 95% of everything it is to me --- a nightmare maintenance problem in waiting. Would I spend $50 thousand something on it ? Nope! In fact I think my next car will be anything produced before 2015. No I know why the guy that service manager guy that used to hang out with us said, "it is the service department, the shop that keeps the lights on at the dealers."

 

[CR94]

... if you keep playing the radio, you will get a flat battery

Obviously so, but you could play a basic radio a very long time before that happens, IF the car doesn't consume a lot more amperes in "ACC" position than the radio itself does. In my Toyota, putting the ignition pushbutton into "ACC"-equivalent mode with nothing on takes about 4 times as much power as the radio does. Very annoying! Therefore, I no longer listen to radio with the car parked, as I safely could on older cars.

 

[Craig in Canada]

I am not sure if it was mentioned before but with my bmw e90 i have to code the car when installing a new battery so that the IBS intelligent batter system know what kind of battery is installed, agm or flooded And how many amps so that it knows how much/long it should charge and the time accesoiries may work or if they are not allowed to switch on.

Also when you do this the system recons that you install a brand new battery with 0 wear so installing a used battery is not wise.

The IBS calculates the age with internal resistance, amount of starts, amount of running hours, load test, amp drops whilr starting etc...

So i dont know if that is also the case with your car. If the computer is told if it is a different kind of battery the charging behavior might change.

You only need to code the car if you alter the battery specifications (significant different Ah capacity, or chemistry change between flooded and AGM). If you are not altering the battery specification, then you only need to REGISTER that a new battery has been installed.

 

[Flyingdutchman]

You only need to code the car if you alter the battery specifications (significant different Ah capacity, or chemistry change between flooded and AGM). If you are not altering the battery specification, then you only need to REGISTER that a new battery has been installed.

Yes thats correct, then you reset the calculations that it makes.

 

[circuitsmith]

I'm having battery issues with my 2016 Volvo V60 and all this smart battery / smart charging makes me realize that we should tie the hands of engineers. I remember driving in the 1960's we would find a field to have a little party, fire up the radio and have some fun. Unless we were driving some guys car that had a weak battery there was never a problem starting the car to leave.

Now with all this smart technology the computer would start having a fit after 15 minutes. I for one am not impressed!!!!

Actually I believe the hyundai kia always show this after a few minutes with the ignition on, regardless of voltage

I have listened to the audio in my Tucson for an hour+ with no problem, with the key in the ACC position.
.

 

[Jetronic]

I have listened to the audio in my Tucson for an hour+ with no problem, with the key in the ACC position.
.

Have you ever seen that message? I don't think the 2017 already had it.

 

[circuitsmith]

I don't think the 2017 already had it.

It's mentioned in the Owner's Manual.

 

[Jetronic]

it typically appears within seconds after turning on the ignition but not starting the car, like we do when upgrading ecu's or configuring a car for delivery.

 

[X15]

Something not yet mentioned:

Yes, a lead acid battery is ideally kept fully charged at float voltage, however doing so consumes much more water than if it's kept at ~80%. The automakers aren't just reducing voltage for mileage reasons, but also to reduce maintenance requirements. If you decide to modify your charging system it's essential that you properly maintain the water level in the cells.