Actually, the situation is quite different that what people are describing here. We do not have charger connected directly to the load (phone) and the battery as shown in @Tonyr1084's diagram. There is active electronics in between which attempt to supply a constant charge current in one phase and a constant voltage in another phase of the charge cycle. The voltage at the battery terminal is controlled to do this. I do not know if the load is directly connected to the battery terminal or not, but if it is, the charger is presumably measuring the current between the battery and ground.

Bob

 

Actually, the situation is quite different that what people are describing here. We do not have charger connected directly to the load (phone) and the battery as shown in @Tonyr1084's diagram. There is active electronics in between which attempt to supply a constant charge current in one phase and a constant voltage in another phase of the charge cycle. The voltage at the battery terminal is controlled to do this. I do not know if the load is directly connected to the battery terminal or not, but if it is, the charger is presumably measuring the current between the battery and ground.

Bob

Isn't that what the TI charger I cited above claims to do? Of course, you need your VR after the battery and charger.

 

@BobTPH For sure there are different systems out there. Such might be the case with Li-Ion batteries and their charger circuits. The battery monitor circuitry will charge the batteries when needed and will isolate the batteries when the voltage drops below a specific voltage. As I said earlier, there are exceptions to every rule. But the fact remains, current doesn't flow in both directions at the same time. When two currents oppose each other, the net result is current flowing from the higher source to the lower source. Physics 101. And I'm not a physics major. Not even a minor. Not even a hobbiest. Just someone who heard something and is repeating it.

 

@BobTPH For sure there are different systems out there. Such might be the case with Li-Ion batteries and their charger circuits. The battery monitor circuitry will charge the batteries when needed and will isolate the batteries when the voltage drops below a specific voltage.

Yes, there are LV shut downs. By "isolate" do you mean isolate while a higher voltage charging source is attached? Can you please provide a link to such a charger? Neither TI nor Microchip devices I have seen do that.

 

@BobTPH For sure there are different systems out there. Such might be the case with Li-Ion batteries and their charger circuits. The battery monitor circuitry will charge the batteries when needed and will isolate the batteries when the voltage drops below a specific voltage. As I said earlier, there are exceptions to every rule. But the fact remains, current doesn't flow in both directions at the same time. When two currents oppose each other, the net result is current flowing from the higher source to the lower source. Physics 101. And I'm not a physics major. Not even a minor. Not even a hobbiest. Just someone who heard something and is repeating it.

Physics 101
Well, current does flow in both directions at the same time inside the battery (a non-electron or "ionic" conductor) and it does sometimes in places where Kirchoff's law doesn't apply like RF land.

Two way flow is pretty common outside of pure electronic circuits.

• batteries
• human bodies
• all living organisms
• acids (mostly protons flow)
• the ground
• the ocean
• the sky (ionosphere)
• electrolytic capacitors
• aluminum smelters
• liquid mercury and solder
• ion-based smoke detectors
• electroplating tanks
• fuel cells' proton conductor and "solid acid" membranes
• electrophoresis gels in research (esp. DNA testing)
• air cleaners, smoke precipitators, air ion flows
• particle beams
• the vertical "sky current" in the atmosphere
• gas discharge, which includes:
  • electric sparks
  • fluorescent tubes
  • sodium and mercury arc streetlights
  • neon signs
  • the Earth's Aurora
  • lightning and corona discharges
  • arc welders
  • Geiger counter tubes
  • thyratron tubes
  • mercury vapor rectifiers
  • etc ...

Single direction electron current in a metal wire is "real," but it's actually a special case in nature.

 

Well. Did say I'm not a physicist.

 

Well. Did say I'm not a physicist.

Please provide a link to that.

 

Well, the section in the All About Circuits e-book on batteries that I revised seems to be hard to find. I will recover my manuscript this coming Wednesday. In brief, all of the chemical equations for a rechargeable battery are reversible at the molecular/atomic level. The real question is, how far to the left or right does that equilibrium lay?

In other words, and considering a rechargeable battery, the question of whether it is charging or discharging is moot. It is always doing both, even if the equilibrium at the conditions of that moment highly favors one or the other. "Same time" is meaningless in that context. Proton and electron transfers are very rapid, on the order of 10^-17 seconds or less, but even a difference of 10^-23 seconds is not "at the same time," so far as we know.

I interpreted the TS's question at the macro level, not molecular/atomic level. That is, can a battery be net charged and discharged at the same time. That answer should be obvious to anyone here. The net has to be charge or discharge. Hence, my earlier response

 

Well, the section in the All About Circuits e-book on batteries that I revised seems to be hard to find. I will recover my manuscript this coming Wednesday. In brief, all of the chemical equations for a rechargeable battery are reversible at the molecular/atomic level. The real question is, how far to the left or right does that equilibrium lay?

In other words, and considering a rechargeable battery, the question of whether it is charging or discharging is moot. It is always doing both, even if the equilibrium at the conditions of that moment highly favors one or the other. "Same time" is meaningless in that context. Proton and electron transfers are very rapid, on the order of 10^-17 seconds or less, but even a difference of 10^-23 seconds is not "at the same time," so far as we know.

I interpreted the TS's question at the macro level, not molecular/atomic level. That is, can a battery be net charged and discharged at the same time. That answer should be obvious to anyone here. The net has to be charge or discharge. Hence, my earlier response

+1

As usual charged means with energy not particle transfers as currents. So as you say, right side, left side or upside down the net is one or the other IRT energy.

 

Please provide a link to that.

You want a link to my butt? I'd be talking out my butt if I tried to talk Physics on a high level. Even low levels could be suspicious of being full of - um - never mind.

 

Hmm interesting post here...

 

Wolframore The basic understanding of current is that it only goes one direction at a time. Even alternating current, which changes direction, never goes both ways at the same time. I mentioned "Physics 101". On a physics level, current may behave differently, but I'm not a physicist as also mentioned. @jpanhalt and I have been goofing on each other. We really should stay on topic.

Current doesn't go both ways at the same time. See post #10.