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Ray K. asked about a simulation, I think because of current spikes through C3 that were not also through L1 and R1.

Ray, let's think about your circuit.? I(L1) and I(R1) must be the same because they are in series and the only other place for that current to go is into the Sense pin of U1.? That current is small compared to the currents through L1 and R1.

However, that current splits three ways: through C2, C6, and C3.? Now C2 and C6 both have a series resistance (Rser), but C3 in your simulation has none (Rser=0), which means that C3 is the best high-frequency capacitor of the three, and it is the one that tries to absorb the smallest voltage changes dv/dt.? Since the voltage V(OUT) is not constant nor constantly ramping, but has small fast wiggles on it, that translates into narrow (<1 ns wide) current pulses through the ideal capacitor C3.

One way to lessen that in the simulation, is to make C3 not quite ideal.? Add some series resistance to C3.

By adding 0.1 ohm to C3, the sharp impulses are virtually gone.? I do not know what is reasonable.? Maybe a little series inductance would help too, but I did not try.

To answer your question about battery models, I have seen several battery models over the years in this group.? To be honest I did not pay much attention to them, and I don't know how "good" any one is at >1 GHz frequencies.? But I have to wonder if phenomena that happen at such high frequencies have any real meaning in this circuit.? If a 10 Amp current spike lasts for 100 ps, is it real and does it matter?? That corresponds to frequencies near 10 GHz, and I think it is unlikely that it could exist in actuality, with reasonable wires.? It is an artifact, caused by simulating with ideal components that don't match reality.? It's not just C3, it might be everything in the circuit.? The simulation has too much bandwidth for its own good.

That's only my opinion.

Andy