Questions tagged [discharge]

The process of removing energy from a store, such as a capacitor or battery. Stores may be parasitic, resulting in rapid spontaneous accidental discharge, as in a static shock.

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48 views

Time interval quantized?

We have a capacitor fully charged with some voltage. At t=0 we can find the current. This current will change the voltage of the capacitor. However the information of the change of the voltage of the ...
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64 views

Finding practical solutions for discharging and charging a capacitor

I am wondering can I charge and discharge a supercapacitor at the same time like a battery. I have 1.3V going into a 10F 2.7V capacitor in series with a 0.5 ohm resistor. I calculated it will take ...
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max Discharge current of li-ion battery (temporary)

Is my assumption correct that the main limiting factor of maximum discharge current of a Li-ion battery is that the cell heats up too much due to its internal resistance/the current flowing through ...
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3answers
58 views

Pull away voltage (energy) from a DC motor driver board when it does regenerative braking

I have 200 BLDC motor (six-step) driver boards. They work fairly well but, when I tested them on a heavy load (2500 kg), I discovered that they struggle when braking the motor. The PID algorithm can ...
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How do I conduct an experiment to find the discharge curve of a lithium ion battery?

I want to conduct this experiment with a multimeter only. What sort of load do I put? I used a Sony Li-ion Np-BPL battery model and after full charge, I put the battery across a load of 1k Ohm; ...
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battery discharger/charger

I'm working on ebike battery's and I'm looking for something. I have a li-ion discharger (36V 5A) and the batteries are in blocks of 3 cells (in parallel) I want to sort them and remake batteries ...
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1answer
95 views

What is the purpose of this coil in a medical defibrillator?

Please can someone explain the function of L coil in this circuit? This schematic is just medical defibrillator, but almost every capacitor discharge circuit has some series coil. Is it some kind ...
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54 views

Calculating capacitor discharge time constant with dc source and constant current source

I have a 1.8V dc source with 40 ohms series resistance, which models a battery. In parallel, there is a 10uF capacitor. At t<0, the mosfet is off and there is no load delivered to the output, so ...
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25 views

Voltage monitor when discharging

I am trying to make a discharge system that use 2R2 resistors and relay to engage the system, until here everything is fine, I can trigger the system and discharge the battery. I thought, that I ...
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2answers
110 views

How to fully discharge supercapacitor?

My biggest problem is when I discharge a supercapacitor, let's say 100F 2.7V, I use a boost converter, but all boost converters have a minimum input voltage of about 0.9V. But the capacitor still has ...
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40 views

Deep Discharged Primary Battery Pack Voltages

I deep discharged two 4 cell (2S2P) 7.2 V Lithium Thionyl Chloride battery packs each connected to a GPS tracker. I ran the two packs until each GPS tracker stopped communicating. (can't be certain ...
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47 views

swapping the ground reference on a transformer's secondary winding

I'm looking to build a [simple] high voltage power supply in order to make electrets via corona discharge. I'd like to be able to fabricate both positively and negatively charged electrets using this ...
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1answer
42 views

What is the best general purpose variable resistor in a battery discharge circuit (10V < Vbat < 50V)?

this is a very specific question and i'm unsure if this is the right place to ask. I am constructing a battery discharge circuit. The discharge circuit specifications: To be able to discharge ...
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1answer
42 views

How can this high-side IGBT drive work without exceeding maximum Vg-e

I was reading an article that creates a device that model the I-V curve using on capacitive loads. In the article they using IGBTs to charge and discharge the capacitor. This is the circtuit that ...
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2answers
71 views

Calculate time it takes for a capacitor to discharge, when it is applied to VGS of a transitor

I want to usea 1uF capacitor to create an electric field between Gate and Source (VGS applied to dielectric) of a transitor. simulate this circuit – Schematic created using CircuitLab Since ...
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1answer
62 views

Calculate Capacitance Value and Voltage Rating in the event of ESD Pulses

I have a input power filter circuit. It has ESD Protection capacitors which help to protect the downstream circuit from ESD Pulses. ESD Capacitors Specifications : C0001, C0002, C0003, C0004 = ...
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59 views

555 Timer astable mode, capacitor discharges only through R2, why?

I'm pretty new to electonics so please bear with me... I'm looking at a standard 555 timer astable circuit. When the capacitor is discharing, I am having trouble understanding why it discharges only ...
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Battery fast discharging

It is my first question on this forum. I have a problem with my arduino project. I am working on a mobile robot. I use L298P Motor Shield for controlling the two 5v gearbox motors. The power supply is ...
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44 views

Practical estimate for a capacitor discharge through a resistor and an LED in series

This question was asked before, but I am struggling with the same question and I can't figure out "how to deal with it in the real world" as someone put it at the time. Olin's approximation is the ...
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1answer
47 views

MOSFET start up

The schematic is an approximation of my circuit. I am trying to know when SW2 is closed. So I have a voltage divider there to detect it. But what happens is when V1 is activated both FETs conduct ...
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1answer
25 views

RC Calculation With Charge Already On Capacitor

Is there a formula for charging/discharging a capacitor which is already charged to a certain voltage? For example, if I charge a capacitor to 3v, then switch to a 1v power source, how can V(t) be ...
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2answers
40 views

Simultaneously Charge and Discharge a LiPo

I have what seems to be a rather common problem, a circuit in which i wish to be able to simultaneously charge and discharge (use) a LiPo battery. The "charge" going "into" the ...
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1answer
48 views

Help - Battery discharge protection circuit

I am working on a LED (3 V/20 mA) torch circuit powered by 3.7 V/1000 mAh Lithium battery. Am planning to add discharge protection feature to this circuit. If battery voltage go down to 3.3 V the ...
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1answer
47 views

Calculate power on time of a buzzer

I would like to use a 5v active piezo buzzer to beep for a second or two. When the relay is on NO the capacitor will charge from the dc source and when the relay is on NC the capacitor will discharge ...
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Lithium coin cell battery showing randomness in voltage - Do batteries build up potential difference like a capacitor?

I've experienced Lithium coin cell batteries giving an initial spike in voltage discharge and then quickly dying down to very little voltage. This previous question (Lithium coin cell battery showing ...
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2answers
67 views

Help understanding secondary cells discharge curve

This is what I've understood about the process of discharging of a secondary cell. If I have a rechargeable cell, full charged, and I make it discharge at a certain constant current, let's say 1A, I ...
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Jeita compliance for discharge?

I know there is a Jeita compliance charging scheme for charging batteries. But is there such certification for discharging them in the function of temperature? The following is an image of the Jeita ...
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1answer
84 views

How to discharge batteries using bench PSU?

I've heard that if you can have negative current in PSU, you can use that to discharge batteries. Is this true? If yes, how to design/modify a linear bench PSU (which have transformer with several ...
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1answer
108 views

How to use a (cheap) BMS for discharge only

I'm building a small robot (for the context, with a pi zero, a PCA9685 motor controller, 8 small servo motors a regulator and an Ubec) fully powered from a 2S 18650 battery. I've inserted a (cheap) ...
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176 views

Discharging a capacitor without a resistor

Is the following circuit considered un-safe? That is, can a capacitor be discharged with a bare wire connecting the two terminals, or should some resistance be applied? Why or why not? Additionally, ...
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67 views

Why is actual SOC of a battery actually higher than what is displayed

So I read a document today which said that a higher SOC level (around 20%) is displayed as 0% to the user in vehicles, thus reducing the total capacity of the battery. My question is that why is that ...
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139 views

When do we need a bleeder resistor?

In the power supply design that I have, I used a NPN transistor to pull constant ~10mA from the linear regulator: simulate this circuit – Schematic created using CircuitLab Before the ...
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1answer
67 views

Custom spot welder design for very small scale

This is an R&D project to test feasibility. I need to try and weld a fine tungsten wire (50 micron) to a small piece of copper. The obvious solution (to me) is to place the wire on the copper and ...
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1answer
85 views

Is it possible to get a continous power with a constant current demand from a battery

So lets suppose I have to design a battery which has a continous power rating , if my load draws constant current ofcourse the battery will discharge and the SOC drops and so does the voltage. How in ...
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2answers
71 views

How to design a switched mode battery discharger

I have a very basic understanding of switched mode power supplies and know that this is a simple buck converter suitable to e.g. charge a 12 V car battery from an input of, say, 24 V, with a dc ...
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2answers
62 views

Decrease electromagnet discharge time

I have a conveyor belt under which there are electromagnets to hold a piece of steel during movement. At the end of the belt the pieces must be unloaded with suction cups. Over a certain speed the ...
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0answers
374 views

Supercapacitor spot welder - which capacitors to use?

I built a spot welder using a big transformer (approximately 4kW from an old welding machine) but I now need to build a spot welder with more power (more current.) The current spot welder works great ...
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2answers
34 views

Energising Electrostatic Charge Into Nylon Ribbons? Is it possible?

Forgive me for how high level this is but this is the goal I'm trying to achieve here: I want to build a device that has dangling ribbons of a material (lets say nylon for now) that can be actuated ...
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1answer
40 views

In an open circuit, are capacitors still in “series”

In the picture below, there are two capacitors right next to each other in an open circuit (ie the wire with V2 written above it does not go to ground). Assume that each capacitor had been previously '...
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Question about charge and discharge of a capacitor

Let's consider the following amplifier: and suppose that a capacitor is connected between the output node and ground. Let's suppose that the inverting terminal becomes much larger than the non-...
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1answer
82 views

Cascade of 555 timer with Control Voltage not triggering

Hi I'm currently working on a cascade 555 circuit, both operating in the monostable mode. I also want to be able to control the pulse width with a voltage so am using applying 0-5v to the ctrl pin (...
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1answer
71 views

How should I drain a capacitor in a rectifier circuit?

I am trying to learn how to drain a capacitor after disconnecting power from a rectifier circuit. Specifically what I have is a step down transformer from an old wall wart charger that I have modified....
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2answers
202 views

How to calculate a lithium-ion battery's discharge time at a specific load?

How do i calculate the discharge time for an lithium-ion battery at a specific load? Let's say i have a lithium-ion battery with a nominal voltage of 3.7 V, a cut off voltage of 3.0 V and a nominal ...
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1answer
59 views

What voltage do we use for battery cut off voltage?

I have a battery that states a 2.75v battery discharge cut-off voltage. Is that voltage measured at the poles of the battery while it is connected to the load or they are talking about the ...
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1answer
413 views

Why do the polarities of the capacitor change while discharging?

I was going through the working of class D commutation and the article said: As soon as the capacitor completely discharges, its polarities will be reversed but due to the presence of diode the ...
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2answers
1k views

What difference between two discharge resistors in two circuits?

When I search for 220VAC led indicator, I found two circuits one from here circuit 1 another here circuit 2 The purpose of R1 from two circuits for discharge C1 when main AC off, but is there any ...
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When to monitor battery capacity

While other good answers have stated why discharging a 12V lead acid battery is hurtful to it, I seem to be unable to find how you should monitor it. Assuming I want to stop drawing current from the ...
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172 views

Why does a capacitor charge and discharge?

I know that a capacitor would resist a change in the voltage across its two ends. Assume that the capacitor in the diagram is a fully discharged capacitor( 0v across its ends). Now if I connect this ...
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1answer
394 views

How to operate a 12V/5V NE555 timer relay from 12V DC supply and Capacitor

Problem: I need to switch ON a NE555 timer relay from 12V DC supply When the DC supply is switched ON. Also, when I switch OFF the 12v DC supply, the relay should switch ON again as it is a timer ...
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6answers
221 views

True or false: A capacitor stores energy for ½ a cycle and gives it up on the other half, the net energy is zero

I'm hoping someone can give me some more information so that I can confidently answer this question. . . True or false: A capacitor stores energy for ½ a cycle and gives it up on the other half, the ...

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