Mola, I respect your intelligence, especially in your field of expertise.
Reading your post above, the average reader might assume the voltage regulator is always inside the alternator on every vehicle, and that it therefore is incapable of overheating because it has a magical devices within it that prevent it from getting too hot, by lowering the voltage.
I have an Externally regulated alternator, My voltage regulator is external to the alternator, and the only temp sensing ability it has is that which I added to its extra heatsinking below the fan I have added to it, as I often have well depleted battery(s) and ask the alternator to make everything it can, in order to charge the battery as fast as possible, within its limits of acceptance, at whatever voltage I allow to reach the battery terminals, by spinning a potentiometer on my dashboard, which is located next to my voltmeter whose v sense leads go right to my battery terminal. the voltmeter is also right next to my digital ammeter.
So I can spin a dial, watch voltage change along with amperage into or out of the battery at differeent engine rpm, and glance a little farther right and see the alternator stator's temperature, as well as the external voltage regulator's temperature, and the battery's temperature and one other K type thermocouple's reading at the same time. I don't have a hardwired ammeter on the field wire to the alternator but have had my DC clampmeter over that wire too in the past and observed it at different engine rpms with different alternator amperage outputs.
Our 'debate' seems to currently be on whether a failing battery can take out alternator with the extra load of a shorted cell. I have no actual Data on how much juice a shorted cell will consume, but guestimate it to be in the 20 amp range, maximum. You have posted formulas on what the shorted cell might be able to draw, but no actual data, as if it proves your point, somehow.
So is potentially 20 extra amps that the alternator has to make to feed the shorted cell of a failed battery, going to push an alternator over the edge into failure caused by excessive heat?
The Hvac blower motor on my vehicle can draw almost 15 amps when the battery is at 14.7.
My headlamps with high beams i on is just over 15 amps. Are these two devices together going to overheat my alternator?
Of course not.
Of course it will run some degree hotter( remember I do have actual data on this degree) and heat does degrade it with time, and vehicle speed has much much more to do with how hot my alternator's stator gets rather than 25 amps of loading difference. I have insulated the Stator's thermocouple from engine bay airflow too, so dont try and go there.
Is my data relevant to each and every vehicle on the road, of course not, only a fool would declare so, but there are some takeaways here.
The more air movement under the hood with increased vehicle speed, means the alternator fans are likely sucking in cooler air than at idle speed when parked with the hood closed, and better able to keep the alternator cooler.
The voltage regulator, if seeking high voltages with a large load on the system, whether it be a depleted battery or Lights and blower motor or multiple seat heaters and window defrosters, is obviously going to cause the alternator to generate more heat from increased field current sent to the rotor by the voltage regulator, wherever it is located. The load a battery will consume is very different at 13.7 vs 14.7v, but loads like headlights and teh blower motor do not change nearly as much with extra voltage, Again I have measured both at different voltages with my own vehicle and higher voltage does allow blower motor and headlights to spin faster, get brighter and consume more amperage, but it is not 1/2 or 2/3 more like the battery.
At low rpm, the alternator's fan is incapable of moving enough air through an alternator to keep it cool, and a slow spinning alternator will be fed considerably higher field current to maintain system voltage at low rpm, and the field current rapidly declines with more engine and alternator rpm.
So perhaps Idling parked with a battery with a shorted cell with lights and fan motor on High can overheat an alternator, but you claim that the voltage regulator inside the alternator will prevent this from happening, even though many vehicles have their voltage regulators outside the alternator casing and no independent alternator temperature sensing ability.
I still want actual data on how much extra amperage a battery with a shorted cell will consume, not some formula.
I have collected almost all other charging system data possible, with my own vehicle, but for the shorted cell data. I've not had a battery with a shorted cell since 2008. I'd love to collect the actual data, but my last flooded battery got turned in for a core charge before it became a 10.5v battery.
One of the cells was using a tremendous amout of water and would bubble without charging or discharging but it remained a 12v battery and it required no more than 4.5 amps to be held at absorption voltage when it was fully charged, and 2.2 amps at 13.4v. Again, this is actual data.
If I have actual data on a 80% + charged 12v battery reading 10.5v, meaning a shorted cell,
I can then apply that much extra load to my own alternator, at various engine rpms and speeds and collect actual Data as to how much hotter it gets when it has to supply X amount more amperage.
The Data I have collected on a weak failing battery, without a shorted cell , is very enlightening. It does require more amperage to be held at any given voltage than a healthier battery, but it is only 3 to 5 amps more. is 3 to 5 amps extra going to push an alternator over the edge? of course not.
The whole failing battery, taking out an alternator, is an Old wives tail, and it does NO ONE any good to repeat it over and over again as it has no basis in truth. Yes failing batteries and failing alternators do happen often in a similar time frame, but it is much much more likely a failing alternator took out a weak battery from keeping the weak battery at an even lower average state of charge, and at low rpms the failing alternator islikely incapable of meeting the vehicle loads so this weak failing battery then has to make up the difference, and then never gets recharged by the weak failing alternator.
Thew only question here, is how much amperage does a failing battery with a shorted cell consume compared to one without?
Does ANYBODY, have actual data on this? or just really strong opinions that they are right.
If it is 5 amps it is not going to overheat an alternator.
If it is 20 amps, it is likely not going to overheat an alternator, unless the alternator is already failing with a shorted stator or failed diodes, or if one is idling with the hiugh beams on, blower motor on highest possible speed, on a hot night with a hot engine in an engine bay with extremely poor air circulation near the alternator..
Arguing chick or the egg does nobody any good, nor does repeating old wives tales based on incomplete knowledge, zero experience, and NO actual data.
All it does is reveal the degree of intellectual insecurity and level of self importance of the individual.
I've one more post I will add on Bitog before going back to lurker status, not in this thread, as obviously I have been wasting my time trying to enlighten members with my experience and actual data regarding lead acid batteries and their proper charging in order to get maximum performance and longevity from them.
