Saw enough in that article I would not believe anything they write even if on a subject I was completely ignorant.
A bigger battery, if still healthy and well depleted, can indeed put a larger load on an alternator, when the voltage regulator is asking for the same voltage as it would on the smaller battery.
So if someone were to drain a larger newish healthy battery to dead, then jumpstart it, then idle/ parked to recharge for 2 hours, the alternator rotor would be fed more current by the voltage regulator and every component involved in charging would get hotter and wear out sooner.
But, if the vehicle were not just idled, but highway driven, the higher alternator rpm would require less field current sent to rotor to maintain the voltage as desired by the regulator, and highe alternator fan speeds, as well as underhood airflow would cool it, and if an internal to alternator voltage regulator, it too would run cooler as it would be passing say 2 amps at 9 volts to make 47.27 mps to maintain 14.1v at 2k rpm instead of 7 amps at 700 rpm to make 47.27 amps.
I've shoehorned the largest TPPL AGM battery I could fit, modified the tray so I could shield it from convective and radiant heating, yet allow heat dissipation when high amperage recharging.
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These batteries, when well depleted and offered as much as they can drink, at high electrical pressure, 14.4v plus, are the raging alcoholics of amp gobblers, at least until about 85% charged. large Banks of TPPL AGMS in boats are known alternator friers, and often charging systems in boats are TPPL AGm battery killers, as they cant come close to making the minimum desired charge amperage when well depleted to keep the TPPL agm performing properly.
Odyssey wants no less than 40 amps per 100Ah of battery capacity in deep cycle duty. their group 31, 13"long x 6.5" wide x 9.75 tall and 78 lbs, 100AH, 1150 CCA is about the biggest car jar battery size available. Deep cycle one of these and only feed it 20 amps max, even if charged to truly full, will half the cycle life compared to if it were fed 40 amps, all other factors being equal. Never cycle it below 80% SOC and it does not much matter as to max charging amps.
My vehicle calls for a group 34. I've easily fit a group 24, a 27, and not so easily, a group 31. The Northstar 31, when new and well depleted, could easily max out my 120 amp alternator, at both idle( 50 amps), and at 2150 rpm (121.4 amps) for a surprising amount of time.
parked idling maxed out at 50 amps and it would quickly rise well above 180f and temp increase just accellerating from there.
Idling at night, at red lights were the worst in this regard.
Driving 74mph making 121.4 amps, it would sit at 139.5f, for the 15 or 20 minutes my system was able to apply that much load to the alternator.
I've got external voltage regulator temp and current data too, but that would just confuse the topic.
A battery is an electrical filter. The bigger the better, but 'better' is subjective opinion, as is 'needed' or 'acceptable,', or 'desirable'.
Now if the larger , new, well depleted battery can ask for more current than the original cabling is rated to safely pass, then perhaps its inline fuse would blow. That original fuse to battery blowing when the alternator is maxxed out, making everything it can, could be considered a load dump, the maxxed out alternator might spike system into the 30vDC range, perhaps significantly higher for a few microseconds, and that could indeed fry something like an engine computer, and almost certainly the diodes in the alternator, unless field current were cut at the same exact moment as the fuse blowing..
it does make perfect sense to recommend 85IQ joe blow not upsize their battery, as they cant understand the conditions when it could surpass the limitations of the manufacturer's original design
So 'Why!??" is certainly valid, in that case, which for most A to B drivers is highly unlikely to occur.
The Honda 51r battery is about the same price as a group 24, yet less than half the size/ weight.
If the 24 fits, ...,WHY Not?
weight? that extra 24 Lbs gonna tank your MPG, or compromise the fleet MPG average?
Thick vs thin debate...... 0w-20, why?.
The voltage regulation of modern vehicles today can and will vary so widely among makes and models, that so much old school knowledge collated and applied to all, about what is and what should be, no longer applies, as what is most important nowadays, is max profit.
A pallet of group 51r batteries can service how many Hondas,
How about that same weight pallet of group 24's, half as many? Same delivery cost/weight/ size of pallet, half as many batteries.
Millions in wasted profit, silicone baby needs diamonds!!!
Think they care about the battery life, or whether they an 8 year old vehicle is known to be a battery eater, well out of warranty?
That profit has long gone into shiny rocks on the fingers of the executive wives, for whom nothing could ever be good enough anyway, years ago.
its highly unlikely that a larger battery in 99% of vehicles, if it easily fits, will do anything other than extend the time it takes for the battery to degrade to the point it can no longer do its job of starting the engine.
The extra weight might eat the MPGs and brakes negating any savings, or it might not.
If one were the type to think Idling for 2 hours after an unintentional depletion of a new larger healthy battery in august in Phoenix is s great idea, well they are asking a lot from their alternator, and the battery needs 6.5+ hours held at 14+ volts to be returned anywhere near true full charge anyway.
My opinion, stuff the largest battery which easily fits, and if one unintentionally depletes it to the point it needs to be jumped, then dont idle it, drive it, drive it, with minimal DC loads turned on, to the nearest grid powered battery charger at earliest convenience, and give it 12+ hours bringing it to and holding it above 13.6v.
One has to keep in mind many vehicles today have their voltage regulation programmed not about charging the battery to true full, but basically turning off battery charging entirely when it is most beneficial to achieve slightly higher MPG numbers. I know many seem to think the voltage regulation has a thousand sensors and is always seeking for ideal battry life, but Ideal to the manufacturer is fleet MPG averages, and max profit. make most last the warranty and caching!!!!
This basically requires they keep the battery in the 80 to 85% charged range, so that when one takes their foot off the throttle, the VR can ask for 14.5v and the battery can then accept 25+ amps, which it could not if it were 99%+ charged.
Lead acid batteries, ideally, want to be kept cool, and as at high a state of charge as possible always, and even if treated ideally, will still degrade to uselessness, in time.
Hotter and lower SOC averages have far far more effect on lead acid battery longevity, than who made the battery and who put their sticker on it and who sold it.
Anecdotes about battery longevity, without knowing the average state of charge and average temperature, are largely meaningless.
Think about heatsoak. the person who drives 45 minutes 5 times a week, then parks facing into prevailing wind, gets 5.5 years from battery A, but then battery B is 4 days a week, 2 weeks a month, parked facing away from prevailing winds, and lasting less than 2 years.
"Battery A was great, Battery B 'sucks!!!",
but battery A and B could perhaps be identical and the only difference is the average state of charge and the average temperature.
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