Anyone top-off charging a lead-acid battery as part of regular maintenance?

[Sequoiasoon]

I think my kids, as a rule, turn on the headlights. If that was taught in driver's ed, then that's what they do.

Coming into the time of year where the lights are on more often than not.

But not a bad idea, all around.

Not something I think mine ever had in drivers ed. I don't recall it. Maybe some reference to the daytime running lights at most.

My daughters '08 CRV, my '17 Accord have the dual charge version I think and the '19 Pilot is I think totally variable depending on load. Honda has been doing it for a while for .0001 extra MPG.

I had Pilot with AC and fan on high, front and rear and it still showed 12.8V. Headlights on at any point 14.4V.

With that plug in USB phone charger on Pilot you can also see it go from 12.8 up to 14+ when you hit the brakes. I don't recall on just coasting.

 

[supton]

I had Pilot with AC and fan on high, front and rear and it still showed 12.8V. Headlights on at any point 14.4V.

LED headlights or incandescent? I wonder... LED won't care about voltage, and I think modern HVAC also uses a driver (IC as opposed to voltage dropping resistor), but incandescent lights are very sensitive to voltage.

I have some 2 wire LED voltage displays, I should dig them out.

 

[berniedd]

Yes, I do. Once a week, I charge 7 ampere-hours into all my car batteries. All my cars, whether they get daily use or once a week. I reckon the normal 40 milliamps of engine computer power drawn all the time with the engine off = 7 amp-hrs a week, will have to be returned to the battery to make it 100% full again, for best life. And the daily driver? Well, today's smart alternator is said to stop charging once 80% state of charge is reached, so my routine gets it to 100%, at least till the next time it is used. Again, for best bettery life.

My charger is just a transformer, diode bridge rectifier, and an ammeter. No fancy spiking desulfator outputs. There is no need for me to disconnect the battery from its cables.

 

[JHZR2]

Yes. My low use cars go on charger when they get parked, or within a day of that, to keep the batteries as close to 100% as long as possible. This isn’t practical for high use daily driver cars, but I will top them off if they sit a while, like when we go away, or we do something that keeps them from going to sleep. Not on any real schedule, rhyme, or reason…

 

[Sequoiasoon]

LED headlights or incandescent? I wonder... LED won't care about voltage, and I think modern HVAC also uses a driver (IC as opposed to voltage dropping resistor), but incandescent lights are very sensitive to voltage.

I have some 2 wire LED voltage displays, I should dig them out.

'19 Pilot is factory LED headlights and foglights. It's the ECU's/system itself and I'm sure various things that trigger it.

You could probably easily check on your CRV with a DVM. I know all of my Honda's show not charging for when just sitting there unless I turn the headlights on. They might show initially higher right after starting but drop off soon to lower volts.

 

[barryh]

Because modern cars have smart alternators, they are almost always going to finish a journey with a battery at less than 100% charge. the only time mine gets close to full charge is after long multi hour trips where the the battery will get fully charged eventually even at the reduced charging voltage that smart alternators put out at a steady cruise. Given that state of affairs, I charge mine fully once per week but it will be a little discharged again after the first short trip.

It could be argued that regularly fully charging the battery is effectively a form of extremely mild hybrid. i.e you are reducing the power the engine would otherwise have to provide to drive the alternator. I'm more interested in the batteries long term health though.

 

[Patrick0525]

Start at 14:00 time mark.