Yeah this. My saturn s-series would "remember" knock retard events at particular throttle openings and RPMs for hundreds of miles. Wiping the battery wiped this memory.
New battery, peppier engine?
- Thread starter otis24
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Nope. This isn’t my first oil change! I would have noticed it before.
Only if the battery is absorbing all of the ~1..7kW the alternator can put out---which it won't,either in the scenario LvR explained or with a discharged healthy battery.
that's why I said, 2 to 4hp, that's half to full output. And 120 amps is not a big alternator these days....
you're missing the point. there will be no meaningful difference in alternator load or hp drain between the new and old battery, unless the old one was shorted which it wasn't because it still started the car.
only feasible explanation is the shift points got reset and the OP is interpreting higher rpm shifts as "peppier". even subtle changes in ignition timing or fuel trim are not going to be felt on a minivan.
I've seen alternators run hot from old batteries, while normally the load gets shared, the alternator has to do nearly all the work now. When loads go down the batteries charge more. The alternators often struggle to keep the voltage up when batteries are poor.
Like Mightymousetech, I came across this regularly if not often.
Like Mightymousetech, I came across this regularly if not often.
You have it backwards. A small sample does not represent the large population from which it is drawn. Drawing two batteries that both have shorted cells is much more likely in a small sample than it is in a large sample. Drawing a sample where no batteries have failed cells is also much more likely in a small sample than a large sample. That is the law of small numbers, also called the small number fallacy.
ok.
Just saying a few hp can sometimes be felt. Not interested in more than that really.
Just saying a few hp can sometimes be felt. Not interested in more than that really.
that would mean alternators are normally regulated to
while different vehicles use different charging schemes, they all rely on the alternator to deliver 100% of the load while the vehicle is running.
and as stated earlier, an old/partially sulfated battery will not draw a meaningful amount of excess charging current unless it is shorted, and that is not the scenario here.
perhaps you are confusing "old" with *severely discharged*. a deeply discharged battery will indeed draw a lot more current... as much as the alternator can deliver. but that will happen with new batteries too, if they are deeply discharged.
at the risk of beating a dead horse I have an old cotsco 24F from 2014, 700 cca. this battery measures 517cca and was neglected most of its life. run dead a few times from the kids leaving interior lights on, van left idle for weeks at at a time, etc. its certainly old, and most would consider it "bad" at 70% rated capacity. it was replaced in early 2021 but i keep it as a spare. I put it on my DC power supply at 13.5v and it quickly settled down to about 100ma draw. after an hour its pulling 74ma, or about 1.0w. I don't know how many hp that is, but I'm pretty sure nobody is going to feel it.
That is actually not true. Most newer vehicles won’t even try to charge a fully charged battery. Systems are a lot more complex than that now. The alternator often is not doing anything until the battery is below 60% SOC or similar. So with a new, fully charged battery, the vehicle is likely running completely off battery power, and only charging during deceleration.
welll i'll admit I know nothing of BMWs, but if they really do this it's lunacy. sacrifice a $200 battery to save few cents of fuel? and I've not heard of any american ICE cars doing this. my 2019 toyota doesn't. my wife's 2018 lexus doesn't. i'm not talking EVs here.
I was about to say the same. As mentioned above, as soon as the car learns, it will be back to pre-replacement values. Because it happens so gradually, the owner will not notice. Just as they likely didn't notice any prior performance degradation.
They are not trying to save the owner on fuel, they are trying to meet some fleet fuel economy value. Saves them money on engineering a more efficient car.
I am with the alternator drag crowd. When you run a generator to make power at your home it uses energy. Same with a weak battery. I have experienced this phenomenon on VW aircooled motors plenty of times. They had no computer so they knew nothing. When you just have 40HP when new, it can be significant. Sitting and idling in a car with no computer and turn on the headlight and put your foot on the brake and the motor will slow down.
Pretty much all cars do this now, this is nothing new. BMW has been doing it since 2006. And why would it "sacrifice" the battery? Both my 2010 3 series and 2013 1 series are still using the original battery without issue. If the battery terminal has an electrical component attached to monitor the charge, it likely does this.
sorry, no way an 11yr old battery left at 60% SOC the whole time is still going. your story doesn't add up. and doesn't comport with my own observations. whatever the esoteric charging algorithms are, they are not as you describe.
Yes ...................... but as usual, not reading the whole thread and understanding what is being said is also slowing you down
Hermann
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My old Beemer ran much better after spending a night on the charger. YMMV
