[USER=6]@AudioShockwav[/USER] - that is the event.
When you run an accessory like A/C - it's the Climate control - places quite a load on the electrical - mostly a Hair dryer to small toaster and refrigerator at the same time.
The Clutch is solenoid driven and runs off the main Harmonic pulley - so it too tells te engine it's got a load, so both Idle up for Engine and Idle up for Battery Demand takes place - tops off the battery and keeps the system from cycling the battery too harshly.
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Life cycling of a car battery...
It's easier to think that a dead car batteries electrolyte is pure water...
When it's fully Charged, is highly corrosive Sulfuric Acid...
One of the main reasons for shortened battery life is not from overcharging - it's the lack of sensitivity to the drain to charge
- - for the Battery is always seeking a charge,
- when it has to deliver,
- a chemical reaction takes place, mostly it's reversible
- - but not without reduction
- - you lose water; Hydrogen, Oxygen and Sulfur Ions
- then "calcification" occurs when the sulfur binds to the lead
- - forms a sulfate.
- - molecule by molecule you lose plates this way from the internal resistance and the draw of power - even in micro amps
- - that chemical reaction takes it's toll on batteries.
So when he runs the engine in a condition (off Park) Parking Brake On - yet A/C can run (runs even while parked) but in this case you may want to put it out of park and set Brake so you can put the ECM in a Drive condition - even though it's in Neutral - not in Park.
A secondary note inclusive:
The nature of long idle parking is not conducive to long engine life, so they tend to place the "Park" condition as a Closed-Loop Idle control condition - meaning that the engine will not cycle repeatedly in Idle up condition unless a specific condition in this Closed loop is demanded, it then puts itself out of closed loop (an emissions control condition of low-emission little / light load) and into an open loop condition so the Idle speed can be controlled without regards to long term idle emission issues - even though you idle for long periods of time - you're putting the ECM in a Open loop condition of power demands. (This varies amongst the makers but the premise is the same - reduce long term idle emissions as a part of reductions to Greenhouse Gasses and Toxic emissions CO - CO2 - NO2 control)
When the engine senses load, the Idle engages because again, the ECM/PCM monitors the battery condition more closely by using the Differential condition that Block ground to Frame Ground changes under loading.
And as said earlier - Battery Capacity is changing; todays technology is different from just a few years ago, and isn't going to revert back any time soon. They're too far into the battery technology to do so, the older vehicle charging systems with need upgrades soon enough because of the now different demand the battery will appear as to the charging system. The battery internal resistance is changed, and older systems relied on a large voltage drop to excite the Rotor to obtain more energy from it's field into the Stator coil winds and the field it generates from it - to generates enough change in the STATOR to push current into the battery - on top of the fact that the Battery becomes the largest Power Filter in the system - a big Capacitor taking in and smoothing out charge all the time the engine runs and tries to top off that battery - the STATOR winds itself generates the pulsed DC current - so it's never smooth even at driving speeds.
Sidebar:
So you know, most newer Diode Trios are Full-Wave - older systems were "half wave" single ended - so now use 6 diodes instead of the three.
On top of, they are mostly Schottky types allowing for more current and voltage presence upon demand. (Less power drop/losses per rotation of Rotor)
