I've learned a lot of things on this forum over the last 11 years, and I also unlearned a lot of things I misunderstood, or incorrect things I was told by people I thought knew more than me.
I was once told by an elder, who I thought knew their stuff, that it took no less than 5 minutes for the alternator to replace that which was required to start the engine, I believed it. Seemed perfectly reasonable and I had no way to disprove it.
When I had the tools and ability to easily check this figure myself, with a chock full healthy AGM that hits the 0.0x amp wall at absorption voltage when fully charged, i did so, and it took 45 seconds or less for the amps to taper back to 0.0x at 14.7v.
So for years and years, I believed that which was untrue, untested, and even repeated it myself to others who likely thought I knew my Stuff.
But reality, and employing measurement tools far more than accurate enough for this test, proved, that at least my manually controlled alternator, can return to my battery, what My starter used to start my engine, and just how long it took, and that that 5 minute figure was off by more tha a factor of 5. Data, reality. Period.
Now not every vehicle seeks 14.7v right after starting the engine, nor does every vehicle have 108 amps available to reach that 14.7, nor cabling which can pass that much current, or a battery which can accept that much current.
But I can say without doubt, that my starter motor uses such a tiny portion of battery capacity to start my easy to start engine in a mild climate, that my quite capable and well above average charging system can replace it quickly. At least when the battery was newer and healthier.
Currently, it takes much longer for amps to taper at absorption voltage, no matter what charging source I use on this well aged and used battery. I've not bothered watching my shunted ammeter lately with the engine running, nor timed it to see just how long it now takes for amps to retaper to what the battery was accepting before the engine start. No need, though curiosity is rising again in response to being called out on it by an apparennt cloud yeller.
I pretty much never drive for less than 3 minutes when I start the engine, so returning what I used to start the egine is never a concern as I know 3 minutes is at least 2 minutes longer than is required. So I don't bust out the timer and watch the shunted ammmeter each and every engine start anymore. There is No point.
I Do watch how low the voltage falls during engine cranking viewing it as a personal load test for comparison, how high the dashboard hall effect ammeter goes once started, and how quickly it tapers after starting the engine, mostly to guestimate the state of charge, as I can dial in any dang voltage I dang well choose, and how many amps are flowing into a battery at absorption voltage is extremely revealing not only to battery state of charge but to state of health as well. Especially once one is familiar with one specific battery, and also has a recently reset battery monitor saying how many amp hours from full it is. how fast amps into my taper at absorption voltage is incredibly enlightening, and I do it every time i drive, as i have more than accurate enough gauges right there.
What was once a concern of mine, was being able to insure that the well depleted battery was charging as fast as it possibly could every time the engine was running, and NOW, as long as I am turning 2000 rpm, I can insure that, and the tools which allow me to see that, and the wiring and manual voltage regulation which allow me to command my alternator to do my bidding, also allow me to see just how long it takes amps to taper to the same level as before I started my engine.
But in fairness, not every vehicle will seek high 14's after engine starting, and some of these modern vehicles can care not one whit less about battery longevity. Perhaps 5 minutes is accurate with stock wiring and a voltage regulator only seeking to achieve and hold 13.6 and an engine which cranks for several seconds. Perhaps with timid voltage regulation 5 minutes is quite generous. But I qualified my claims with 14.7v.
Mine starts in 1.5 seconds or less when overnight cold, I have 108 amps available to seek and hold 14.7v, 15.5v if I command it with a flick of the wrist, and the time it takes for amps to taper back to the same point it was at before engine starting was measured at the same voltage was less than 45 seconds. No BS, no wildash claim, no wildly inaccurate measurment tools making this observation invalid or me a BS artist. So F. U !!!
Having BS called on this is insulting, and I recall the guy who once told me that it takes no less than 5 minutes for the alternator to return that which the starter used, and just how wrong he was. That guy is still my friend, well my senior, still respected, but when he postulates theory with no data, states opinion as absolute irrefutable fact, or repeats something someone else told him with no supporting data, I ignore it/ him, on that topic, and that's precisely where GTE is in my mind on this specific topic.
But I still got a lot to learn, and can admit that.
I started this thread to hopefully learn more by discussing the possible improvement in lead acid batteries, now that it can hurt the bottom line of Automakers, since some of them are now intentionally seeking to cycle engine starting battery to eek out minor MPG gains, put higher MPG estimations on the new car windows, get more market share, fool the consumer......
Will the possible pressure by Automakers fearing their bottom line when havng to warranty rematurely failed batteries indirectly lead to improvement in the lead acid battery?
Apparently no one here wants to discuss that possibility, and would rather yell at clouds.
The deep cycle battery market has been a tiny market share, compared to the Automotive starting batteries in the worldwide new car market. Many Modern vehicles are intentionally cycling the starting battery much deeper than before, and batteries are failing quicker than usual because of it.
Shakes fist at sky an apoplectic fit. How dare things change!!!
