Imagine batteries connected to a charge controller and a load at the same time. When the load asks for power, and the charge controller delivers power, there are three possible situations:
- P_in > P_out: there is netto power going into the battery: charging
- P_in < P_out: there is netto power going out of the battery: discharging
- P_in = P_out: battery keeps unchanged
The power that the battery loses/gains is |P_in - P_out|, but in the system as a whole there's flowing a lot more current than that. Does all the current go through the batteries in this system? Or is there no current flow through the battery in situation 3 (such that the current is flowing directly from the charge controller to the load).
Do the batteries wear down in situation 3? Or are they just completely unused then?
EDIT: I think my question is different than the so-called duplicate, since it's more about the physical working of the battery. I made a basic diagram about my question as asked by Olin Lathrop:
So the question boils down to: are the light green and pink currents present (comparable to a dynamic equilibrium state in a PN-junction at rest due to drift and diffusion, when there's also a lot of electrical current flowing throught the component but no net measurable current), which would make the battery wear down? And if they're not, why? Is "path of least resistance" a sufficient reasoning to state this?
Also I am not completely satisfied with the answer given in the other topic, since he tells it depends on the kind of charge controller. If the charge controller delivers e.g. 24W at 24V (so 1A) and the load asks 12W, why wouldn't that current go to the load? Or would the charge controller then deliver only .5A due to the applied resistance (the load), and neglegt the battery? And what will happen with the rest of the energy that the charge controller receives from its source (which is thus 24W-12W=12W)? Will it be dissipated somewhere?
I am talking about a system where charge controller, battery and load are always connected (a stand-alone solar electric system).