Overriding a "smart" battery management system

Like many modern cars the Tucson reduces battery voltage when it decides the battery is charged “well enough”.
It does this to mainly save a little fuel and also avoid over charging the battery.

I have a voltmeter plugged into a 12V port so I can monitor system voltage while driving.

When the battery is full (or nearly full) system voltage drops to 12.6V, with 4 exceptions.
When steady cruising it raises the voltage to 13.x or 14.x (varies with temperature) volts for a few minutes every hour or so.
When coasting and no throttle input it rises to 14.x, similar concept as regenerative braking, capturing wasted energy.
Turning the HVAC blower to high raises the voltage to 14.x.
Turning on the headlights raises the voltage to 14.x, we don’t want headlight brightness changing up and down.

I’m a low mileage driver, about 5-6000 miles per year. I don’t drive to work.
With COVID I’m driving even less. Few visits to family, no road trips.
Some weeks I only drive to the grocery store, one mile each way.
Takes me up to 2 months to burn half a tank of gas.

For 2 years I’ve kept a 10 watt solar panel on the dashboard to help keep the battery full.
I park on a city street; no plug-in access for a battery maintainer.
It does a good job, bringing battery voltage as high as 13.5V after a few hours in the sun.
But with long winter shadows coming and cloudy days it would be nice to get a little extra charging.

What I’ve started doing is turn the headlights on for trips 30 minutes or less, or turn them on for the last part of longer trips.
That keeps the voltage at 14.x volts for some extra charging time.

Interesting analysis! Thank You!

I’ve not seen that on my older Ford and GM vehicles equipped with factory voltmeters. Does this Tuscon have electric assist power steering or old-school hydraulic?

Electric PS. It’s a 2017 BTW.

Wifey drives car once a week. I drive daily. Both of our cars batteries seem fine. Friend has 2020 Infiniti. He puts charger on battery too. Makes him feel better.

My Shop-Rite supermarket is only 3 miles away, but I almost always take the longer, scenic route–rather than the direct route–so that the engine warms up more completely and the battery gets a better charge. This way, I drive 7 miles each way instead of only 3.

My routine in the Era of Covid is to do that drive once each week, plus a once a week drive to LIDL for their goodies from Germany, Austria, France, and Italy, and a once a week jaunt to Costco, during their early-morning “senior hour”. The LIDL trip is ~8 miles each way, and Costco is exactly 7 miles each way.

When you throw in my outings to the nearby state park a few times each week, I put ~75 miles on the odometer each week. Every 3 weeks or so, when the gas gauge gets down to the halfway mark, I fill the tank.

What kind of battery came in your car? AGM or conventional?

It’s a flooded battery. I am aware that AGM do not have the extra liquid to tolerate overcharging.

I’d rather not burn the extra gas. Plus, the route wouldn’t be scenic, navigating city streets peppered with aggressive and inattentive drivers.

Well, then you’ll need to fit in a long drive sometime. I do it once a week for the battery and the oil.

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I’m taking the advice of several here and not commenting on something I know nothing about. I’ve got one of those little volt meters too but I just plug it in from time to time to check the system and never really leave it plugged in. Then I’ll test the battery and maybe put the charger on the car that just sits. I usually try to get out and go someplace every day though to the post office, hardware store or someplace. It keeps the car going and me somewhat sane.

I make a grocery run every 19 days to 2 weeks,. That seems to be enough to keep the ( year okd conventional battery in my 2012 Camry with electric steering happy. I have a 6 amp charger and a float charger but if the car has nt acted uo in the 8 months f covid, why worry now?

I thinl some of this post shows that many of us are suffering form a lack of mental stimulation.