2018 malibu battery light on mpg

In response to Ed92626 That sounds reasonable but as I am coasting al my electrical units are running full blast, radio, fan ac, lights. so in all things considered I would still say I am pulling the same amperage as nothing turns off. The only that happens is the engine rpm drops down which in fact I believe would slow down your charging rate. ??????

Most cars, while the engine is running, have a charging system that will generally produce a voltage between 13.5 and 14.4 volts. The charging system needs to produce more voltage than the battery rated voltage in order to overcome the internal resistance of the battery [5]. This is due to the fact that the current needed to recharge the battery would not flow at all if the charging system's output voltage was on par with the battery voltage. The charging rate will be faster if there is a greater difference of potential (voltage) between the battery's voltage and the alternator's output voltage [6]. For battery charging to occur, the alternator’s voltage must exceed the battery’s voltage. Alternator may not generate sufficient charging voltage until alternator speed is greater than about 2000 RPM. Typically, alternators have their full output rated at 6000 RPM but can continue to spin up to 12,000 RPM or more without any additional increase in output. The speed of an alternator is different for different type of car. The speed of an alternator depends on the speed of the engine. For a racing car, the ratio speed between engine and alternator is usually 1:1. For a drag car, the ratio is usually 1:2. And for street use, the ratio is usually 1:3. When voltage causes current to flow, energy is converted. This is described as power. The unit of power is the watt [7]. As with Ohm’s law, any one value can be calculated if the other two are known. Power = Voltage X Current (1) P = VI or I = P/V or V = P/I A vehicle charging system has been represented in Figure 2 as three blocks, i.e. the alternator, battery, and vehicle loads. When engine is not running, the alternator voltage is less than the battery voltage so current flows from the battery to the vehicle loads and the alternator diodes prevent current flowing into the alternator. When engine is running, the alternator output is greater than the battery voltage, so current flows from the alternator to the vehicle loads as well as the battery. This implies that alternator output voltage must always be above the battery voltage during operation of the engine. However, the actual voltage used is critical and depends on a number of factors [8]. Fig. 2. Block diagram representing the vehicle charging system. The relationship between alternator speed and alternator current is shown in Figure 3. The current output of the alternator is speed-dependent. The speed of the alternator depends

Hey Ed I do appreciate the input you sound like the first person who might have a clue. I did slip up forgetting the rpm would remain the same. But the way I am seeing it the electrical load is also going to remain the same. So the only thing when I lift my foot off the gas that is going to change would be fuel consumption thus the 99 mpg in the pic but I still don't understand the green battery light as like I had said your electrical load has not changed all of the accessories that you are using would still be drawing amperage. The only thing and maybe I am misunderstanding you is are you saying that the dam light thinks I am not using current because the fuel economy is 99 mpg which would make it total B.S.?

Hey Ed so this morning I did a little test. At 80 mph and about 2500 rpms I let the car coast the green battery light came on, now the odd thing I thru it in neutral the engine rpm had not dropped off yet but the green battery light immediatly went from green to gray. So I would assume the alternator was still charging at that point. Your thoughts???