What are you really measuring as a battery discharges?

In summary, the conversation discusses the measurement of battery power on devices such as phones. The measurement may be shown as a graphic or as a percentage, but what does it actually indicate? It could be measuring voltage or the remaining capacity in amp hours, and this is often monitored by an internal circuit in LI-ion batteries. This is beneficial as it is dependent on the specific battery being used. More information on this can be found in the provided link.
  • #1
ptownbro
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Think for example a phone or any devices that shows the amount of battery power is left. It shows it as a graphic where you can deem whether it's full, 3/4 full, 1/2 full, 1/4 etc... or shows the actual percentage. What is that measure really showing you? Voltage? Amp hours left (which is the capacity I think)? And, how is it calculated?
 
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  • #2
As a battery discharges the voltage drops under load. This is mostly due to internal resistance increase.
http://www.mpoweruk.com/soc.htm discusses it. It's possible to monitor this externally.

But. most LI-ion batteries have an internal monitoring circuit that reports charge and discharge data back to the operating system. This is best because the data is so battery dependent.
 

What are you really measuring as a battery discharges?

As a scientist, I understand that this is a common question when it comes to batteries. The five most frequently asked questions about what we are measuring as a battery discharges are:

1. What is the voltage of the battery?

The voltage of a battery is the amount of electrical potential difference between the positive and negative terminals. As a battery discharges, the voltage decreases due to the depletion of its chemical energy.

2. How much current is being produced by the battery?

The current of a battery is the rate at which electric charge flows through it. As a battery discharges, the current decreases due to the reduction of its chemical reactions.

3. What is the state of charge of the battery?

The state of charge is the amount of remaining energy in a battery, expressed as a percentage of its total capacity. As a battery discharges, the state of charge decreases.

4. How much energy is being delivered by the battery?

The energy delivered by a battery is calculated by multiplying the voltage and current over a specific period of time. As a battery discharges, the energy delivered decreases due to the decrease in voltage and current.

5. What is the internal resistance of the battery?

The internal resistance of a battery is the opposition to the flow of electric current within the battery itself. As a battery discharges, the internal resistance increases due to the depletion of its chemical energy.

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