# Tagged Questions

Devices to store chemical energy and convert it to electrical energy.

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### Charging of a battery

A battery has an Emf 6 Volts. It is completely discharged. It is charged by maintaining a potential difference of 9 Volts across it. If the internal resistance of the discharged battery is 10 ohms, ...
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### RC circuit discharging capacitor, trouble understanding

If we apply loop rule while charging the circuit we get: $$\varepsilon -iR-\frac{q}{C}=0$$ The way I understand, we follow trough the circuit just before the battery, as we move trough the circuit ...
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### Question regarding Kirchoff's loop rule

My problem is that there are n cells connected in parallel which are connected to an external resistor. Now can we use Kirchoff's loop rule to evaluate the current through the resistor by considering ...
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### If a battery is open on one end but connected on the other, does it raise the potential on the connected end?

If a battery has one end open and other end connected to a circuit will the battery increase the potential at the point of connection?
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### Adding two same DC voltage source in parallel

In a parallel circuit(imagine two branches),with one DC voltage in a branch and another DC voltage in a branch, what is the method of computing the total DC voltage? The voltage through each component ...
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### Short circuit in superposition

I'm really confused about the concept of short circuits. I don't understand, why when you short those two voltage sources, 20 and 10 ohm resistors become parallel? What happens with 4, 12, 15 ohm ...
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### Li-ion Battery charging

Why are constant current mode and constant voltage mode needed when charging Li-ion batteries? Why do we apply saturation charge even after the cell voltage reaches 4.2V? What exactly is 'I-sense' in ...
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### What is the equivalent of the “amount of fuel” for a battery?

I am trying to make a performance diagram of an electrical powered device vs range, speed, etc. I want to compare it using the equivalent of fuel for a battery? I am not sure if it is just voltage... ...
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### What happens in the RC circuit when being charged?

Say I have this RC circuit and at the start, the switch is off (current going from left to right and the starting point is just above the battery). I understand that then the capacitor acts just like ...
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### Estimating the battery capacity using current power consumption and battery percentage

I want to estimate the current maximum capacity (in kWh) having the current power consumption (in kWh) and the state of charge of the battery (in %) available in a time series. I do not have a full ...
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### What are the physical limitations on energy density for a useful, safe battery, and are we anywhere near them?

Energy storage seems to be a fairly major bottle neck in technological development at the moment, especially for important things like clean-energy powered transport, but also for consumer goods. Are ...
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### What is causing a Li-Ion Battery to catch fire when it's not charging or powering anything?

I was just reading about UPS Airlines Flight 6, which crashed because of a fire in the cargo from Lithium Ion batteries. This is a case where the batteries were not powering anything and not charging. ...
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### How to measure resistance of gel electrolyte using multimeter

How can I measure the resistance of a gel electrolyte using a multimeter? I know the formula to measure the conductivity of a gel electrolyte is k = (1/R) * (d/a) where k is the conductivity (S/cm), ...
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### What is the theoretical reasoning behind calculating emfs in series or parallel?

First off, I did some research on my own but the answers weren't satisfactory. The analogy of the water pump makes zero sense as I see no way how "Potential" is even comparable with "Dynamic Pressure"....