Originally Posted by wag123
Where did you ever get the idea that car manufacturers are designing vehicle charging systems that purposely undercharge the battery?
Where did ypu ever get the idea that the vehicles' voltage regulation is highly optimized to recharge the battery quickly to full then maintain it there, thus achieving maximum battery longevity?
Dp you also believe everybody else always has your best interest in mind?
Might as well say they also have designed the battery enclosure with insulation and ventilation so it is never exposed to engine heat.
The fact is that Automakers are not concerned whatso ever with battery longevity, other than perhapslasting any warranty period, if it includes the battery, an th ebeancounters have done the statistics and calculations as to what is most profitable.
Since on this forum it is often argued that thin oils are recommended nu Autom manufacturere in north America, purely and solely to eeeekk out the maximum possible mileage to meet CAFE standards, is it not obvious that the voltage regulation of a vehicle can also be tweeked to eeeek out a fractonal tiny improvement in MPG?
While it is not true of all vehicle, many vehicles of today will delibetely keep the battery at a low enough state of charge, by keeping the system voltage low, so that when one lets off the gas, or is braking, that the battery can accept high amperage frpm the alternator when the voltage regulator commands the alternator to make enough amperage to bring system voltaeg up into the high 14's.
A fully charged battery cannot accept much amperage at all, but a discharged battery can.
So Some, not all, automakers design the voltage regulation to keep the battery partially charged, so that it can accept high amperages from the alternator and possibly increase MPGs by a tiny fraction, the same tiny fraction that thinner oils might allow.
Ideally a battery would always be brought upto full charge at 14.5ish volts right after starting, held at 14.7v until absolutely fully charged, then voltage dropped to just high enough to prevent its discharging while driving. Some might say 14.2v is less abusive and recharges almost as fast. they are not wrong.
So Automakers are not concerned with battery longevity, they are concerned with not overcharging the battery. They are concerned with C.A.F.E.
And while trying to use the starting battery as an ineffective regenerative braking system is a horrendously unwise idea, in my opinion, it does work to some tiny percentage in vehicles which employ it. Unfortunately keeping the battery in a continually undercharged state is very bad for its longevity. Any fuel saved by doing so, is chewed up in the more required recycling of lead acid batteries, their transport to and from the recyclers and the energy used to do so. One could make ethanol comparisons here.
But heres the kicker. batteries still are lasting 2 or 3 years despite being in a chronic state of undercharge by deliberately underchrging them. This more than anything shows how little CCA a battery really needs to be able to start a modern fuel injected engine, and just how far battery capacity and CCA can degrade before it is truly in need of replacement.
My 1989 5.2 liter v8 engine calls for a group 24 and 550CCa minimum. I just started it on a tiny 12 pound 18Ah AGm battery I figure is 170CCA max. So if I were to stick with a group 24 550 CCA battery, It would have to decline to the 200CCA region before I'd really be in danger of not being able to start my engine. Cold temperatures would reveal the weakness sooner as the engine is harder to crank and a battery has less CCA at cold temperatures.
People should really monitor the voltage their vehicle allows. Not just atfter starting, but all the time. If one is seeing 12.7v going down the road, it is not because the alternator cannot keep up with the DC loads, it is because the voltage regulator is telling the alternator to not do much if anything at that point in time. When i get to drive my parents 2014 Stingray the battery voltage is often 12.7 doing 75mph on th freeway mid day, and only climbs higher when letting off the gas or braking. Does every GM vehicle do this since 2014, i have no IDea, I can say this vehicle doe sit, and maintaining 12.7v is not because the alternator is maxed out and cannot bring battery voltage any higher. But did't Gm avoid the gas guzzler tax by forcing 1 to 3 shifts, cylinder deactivation too? is it not obvious that there are also tiny MPG improvements to be had by taking all or much of the load off the alternator when the vehicle is in top gear cruising?
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As for the Columb counter. I actually have one, on my vehicle, counting Amphours out of and into my battery, while also displayng instant amperage into or out of the battery, as well as voltage. I have this becuase i often deeply cycle my battery and want to know the state of charge of my battery. What irritated the living snot out of me is my Vehicles stock voltage regulator, inside my engine computer, would seek 14.9v after starting, but then all too quickly revert to 13.7v after a few minutes, and when my battery is still Far far away from being fully charged. 2/3 more amps would flow into my battery at 14.7 compared to 13.7v, whether it was very discharged or 90% charged. I found this infuriating and ultimately intolerable.
I got so sick of the stock voltage regulator deciding 13.7v was just fine and dandy when my battery was still very discharged, I tricked the engine computer voltage regulator and installed a modified adjustable voltage regulator, and put a dial on my dashboard, next to my digital voltmeters and ammeter, so basically i can almost always recharge the battery as fast as possible, if i have enough engine rpm. this also depends on the loads like lights and blower motor which can suck up 33 amps of my alternator's output.
With a very depleted battery, i can remove almost all the load from teh alternator, by turning my voltage regulator way down to 12.2v. it will only accept 2 to 3 amps when the VR is set to 12.2, but if I crank it up to 14.7v and rev it to 2800 rpm, the same battery will accept over 90 amps. If I rev the engine with the alternator making 90 amps it it lowers rpm much faster compared to when the alternator is feeding the battery at a 2 to 3 amp rate. Some websites say that each 25 amps th alternator is forced to make requires one engine HP with all the losses through the belts an diodes.
Regarding my smartphone having a column counter, It does not. Does yours? I have No idea.
The fact that I was loading the phone battery heavily, then turned it off, and when I turned it back on to find several more % points tacked on to the battery, tell me the % is NOT determined by counting mAH into and out of the battery, but is guessing state of charge % by the voltage of the battery. When the load was entirely removed from teh batery the battery voltage rose. When I tuned the phone back on the phone saw this higher voltage, and told me the phone was not 33% like when i turned it off, but 39%, without ANY charging source having been attached to the phone. If it were columb counting when i turned the phoe back on it would have read 33%
The lead acid car battery works similarly, and this is why equating a voltage to a state of charge is highly unreliable end unwise, no matter how many people believe so or repeat it as unwavering and absolute fact. Voltage is NOT like a fuel gauge. Voltage is ONLY a reliable indicator of state of charge on a rested battery. A rested battery is a battery which has NOT seen any charging sources, or discharging loads for a long period of time. Voltages are not comparable from battery to battery, but only against the same battery at the same temperature when a fully charged resting voltage has been determined when the battery was new and fully charged.
I have a AGm battery wich rests fully charged at 13.16v a week off of the charging source. Having someone tell me 12.6v means the battery is fully charged is completely and totally laughable as if this battery were to read 12.62 rested it would be closer to 65% charged.
One time voltage readings are almost entirely meaningless as to state of health or state of charge. For any comparisons to be valid more data is required, and for any data to be accurate one needs to know when the last charging source was removed, how much parasitic load was on the battery since, and for how long, the temperature, and have previous readings on the same battery to make comparisons to. Only than can one make an accrurate guestimate as to state of health and state of charge which could be verified by an actual capacity test.
Actaul CCA tests and 20 hour capacity tests are so seldomly performed. the true CCA test is almost never done. The true 20 hour capacity test, requires loading a 100Ah battery for exactly 5 amps, and hopefully it lasts for 20 hours before voltage falls to 10.5v. Reserve capacity, how many minutes can the battery output 25 amps until voltage falls to a certain level? These are the only ways to actually test batteries, any other method is guessing, although the more data the better, and the programming and algorithms can be fairly accurate on some batteries, sometimes.
Whether the autoparts store you have your battery tested at, reveals the battery to be bad or good is likely as accurate as guessing whether they have that battery group size in stock and whether they would have to warrranty, it or not. If they have that size in stock, and your battery is from another AP store, the chances thit tests bad go way way up.
Making conclusions as to state of charge, or state of health, with just a few data points, can be overwhelmingly inaccurate.
Determining full charge requires an Ammeter while holding the AGM battery at mid 14 absorption votlages. Even a colummn counter is not 100% accurate in this regard. trust me, i have one, It is not all that accurate as it does not account for peukert effect or heating of the battery when charging at higher amperage rates.
Determining state of charge on a flooded battery is only able to be determined by a hydrometer, but there is a whole bunch of asterix involved in this too.
Educated guessing, well I would trust only those with experiece collecting data to have a remote chance of being somewhat accurate. Not any product which claims to do so.
But the thing is, batteries actually last 2 to 7 years despite all the Un ideal charging and aerage state of charge starting batteries are subjected to in vehicals A to Z. So it can be argued trying to achieve perfect recharge regiment for ideal battery longevity is a fools errand, and ther eis no arguing that they are only batteries, and only rented.
The length of that rental contract is either determined y the vehicle, or by the vehicle and owner, if the owner cres about actually regularly returnin the battery to a hier state of charge, often. he higher the average state of charge nd th ecooler the battery is kept, the longer it will last.
I am seeking maximum longevity from my batteries, as it requires no skill just to throw money at the problem/ replacng premature failures or blaing retailer or manufacturer for user abuse, whether intentional or not, intentionally ignorant or not.
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I am somewhat kidding as I can't imagine any dealer doing a "wall job" on battery replacement but I was still somewhat of a **** and did the trust but verify business right in front of them.
