# 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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28 votes
6 answers
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### How to Calculate the time of Charging and Discharging of battery?

How do I calculate the approximated time for the Charging and Discharging of the battery? Is there any equation available for the purpose? If yes, then please provide me.
• 1,011
26 votes
4 answers
105k views

### How do I calculate how fast a capacitor will discharge?

Say I have a 1F capacitor that is charged up to 5V. Then say I connect the cap to a circuit that draws 10 mA of current when operating between 3 and 5 V. What equation would I use to calculate the ...
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43 votes
4 answers
114k views

### At what voltage is a NiMH battery empty?

I have a battery pack of NiMH batteries. It is ten cells with 1.2V, 4000mAh each, put together in series. So rated voltage is 12V. After charging, i.e. when the charging device says that it is ...
• 531
4 votes
2 answers
22k views

### Capacitor Discharge through Constant Current Source

I was just thnking of how to model the voltage decay from a fully charged capacitor through a constant current source (CCS). A good approximation to this would be to model the constant current source ...
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10 votes
3 answers
6k views

### How deep should we discharge lithium batteries to maximise their lifetime?

Recently I posted an answer mentioning the very classic "lithium batteries like partial discharges, so design your system for limited depth of discharge". But then I wondered: with partial discharges, ...
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25 votes
4 answers
73k views

### How can I quickly and safely discharge a charged capacitor (small and low voltage; <= 42V)?

I am learning how to use capacitors (ceramic and electrolytic from 1pf - 1000uf) and am trying out various experiments using a breadboard. I am constantly adding/removing things to my layout to see ...
• 439
4 votes
2 answers
5k views

### Smoothing a Full-Wave rectifier voltage

I was reading about full-wave rectifiers and came across the schematics below which the capacitor C can smooth its voltage, but I didn't understand one case: We know that when the rectifier's voltage ...
10 votes
2 answers
38k views

### What is 1C charge/discharge rate in battery instruction manual?

Instruction manuals and discussions mention battery charge and discharge rates in terms of "1C", "2C" and so on, without giving an indication of what "C" is. I presume it is not a Coulomb. What is ...
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13 votes
3 answers
86k views

### What is a safe max. discharge rate for a 12V lead acid battery?

I've got a 12V 2.4Ah lead acid battery which I plan to connect a water pump to. I've looked at various pumps, but the one I'm most interested in draws 2.2A. I'm not so interested in how long the ...
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3 votes
3 answers
2k views

### Difference between battery and capacitor?

Can capacitor acts like power supply, in which situations? How related are charge/discharge time of battery and capacitor? Why battery has longer discharge time compared to capacitor? Why we cannot ...
2 votes
1 answer
583 views

### Emitter Follower Power Stage of an Amplifier with Switch-off capacitor

I know exactly how emitter follower (EF) arrangement of transistors works (when used as power current amplifying stage). But according to my book (G. Randy Slone: High Power Audio Amplifier ...
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2 votes
2 answers
3k views

### How does voltage progress during discharge of a battery?

The build: I'm building a portable bluetooth boombox. It's a very simple build. The components I'm using are: Bluetooth amplifier board (TDA7492P) 2x50W speakers Rechargeable battery The amplifier ...
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2 votes
3 answers
10k views

### Area under voltage vs time discharge curve

Will the area under a voltage vs. time graph of a battery discharge curve (with a constant current load) give the amp-hour capacity rating of the battery?
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3 votes
2 answers
7k views

### How do I determine the maximum amp output of a battery pack?

How can I determine the maximum amp output of a battery pack? Some background: I've got a 5-AA battery pack hooked up to a microcontroller and some continuous rotation servos, but there's current ...
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3 votes
1 answer
951 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 = 47nF, ...
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0 votes
2 answers
277 views

### What happen with cells with different current rating put in parallel?

I don't understand how cells behave when connected in parallel. So what if I have two Li-Ion cells: one ist "rated" at 15 amps (which means that the cell is able to discharge at 15 amps without ...
8 votes
4 answers
17k views

### Circuit to safely power-down Raspberry Pi

I want to use a Raspberry Pi as an XBMC server in the car. The XBMC docs say that you should always use the shutdown command before disconnecting the power. I don't want to have to (tell my wife to) ...
5 votes
3 answers
14k views

### High voltage capacitor discharge tool

I am going to be working with many capacitors that can easily kill me (kV range), and I was wondering if there was any kind of industry recommended method/tool for discharging a capacitor to make sure ...
14 votes
6 answers
2k views

### Understanding voltage and current

While reading "Electronics for dummies" went through the following block and I realised that I have some uncleared concepts about electricity: Electrostatic discharge involves very high voltages at ...
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9 votes
1 answer
2k views

### Constant power discharge of a non-ideal capacitor

My employer sells boost converters to hold up motor drives during power loss. These boost converters are fed from capacitor banks. In order to size these banks correctly, we need to take their voltage,...
7 votes
3 answers
3k views

### What makes a device intrinsically safe?

I work in possibly gas filled environments. As such safety recommendations are that I don't use my cell phone, camera and computer while touring around these areas that explosive gas may be present. ...
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7 votes
7 answers
30k views

### Is it possible to fire a spark plug from batteries

I wanted to create a remote fired trigger for a spud gun so I can trigger it remotely. Ideally I'd like to use a spark plug to fire because it should work well for gas mixtures but the trigger is ...
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5 votes
2 answers
4k views

### Making a lithium polymer circuit

I want to create a circuit that will power my Raspberry Pi using Lithium Polymer. My knowledge of LiPo is rather low and I believe they can get dangerous if used incorrectly so I turn here. THe ...
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4 votes
3 answers
2k views

### How synchronous buck converters continue to operate in light load conditions

simulate this circuit – Schematic created using CircuitLab For all intents and purposes lets assume this basic power stage of a synchronous buck design above. Let's also assume a steady state ...
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3 votes
2 answers
1k views

### Pulse Generator - I (Art of Electronics)

In the Art of Electronics book, I don't understand the following phrase .. because current is flowing down through R3, trying to pull it up. Why does this current try to pull the cap up? ...
4 votes
1 answer
1k views

### How to detect low battery of a lead-acid battery?

I've heard that discharging a lead-acid battery to 0% is bad and wears it out. I have a 10Ah 12v lead-acid battery, is there a circuit to tell me when the battery is low?
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1 vote
3 answers
488 views

### Basic Capacitor Discharge [closed]

I found this illustration from the SparkFun website on how a capacitor charges and discharges, but I have some difficulties with it (and capacitors in general): What initially causes the capacitor to ...
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0 votes
1 answer
1k views

### How to make a discharge curve

I am trying to make a discharge curve for one of my batteries that I have. All I know about it is that it is a 1.5V battery. Now if I have to make a discharge curve for it, how would I make one and ...
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-2 votes
1 answer
1k views

### Capacitor discharge after charge

I have this circuit for charging a capacitor: What I need is a circuit for discharging the capacitor after 'V' (the voltage across the 100 µF capacitor) has reached the maximum value of 2V. I ...
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8 votes
2 answers
8k views

### What's a good estimate on how low an alkaline battery voltage can be to still make the battery useful?

Here's a YT video by Duracell about how many batteries declared dead and sent to recycling still have some usable energy. In the beginning of the video there's a sequence where they have a row of ...
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5 votes
2 answers
868 views

### Quasi-peak detector

This is the circuit of a quasi-peak detector: simulate this circuit – Schematic created using CircuitLab where $V_{\text{sig}}$ is the input signal. When the diode is open-circuited, the ...
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1 vote
4 answers
182 views

### Does a low-enough leakage-level battery discharge cause highly asymmetric cell discharge?

A Tale of Two Batteries This is concerning two different 6-volt lantern batteries that have behaved the same exact way (I believe.) Here is a datasheet for the type of battery, a Rayovac # 941 ...
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1 vote
2 answers
291 views

### Discharging a capacitor with an analog switch

I'm designing an op amp integrator with a 100nF capacitor, and need to include a logic level reset/discharge option. I would like to use the DG467 analog switch due to its low cost and small package, ...
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1 vote
1 answer
88 views

### How to maintain equal discharging on batteries

I am currently building a robot that has one 12V battery for each drive motor. The system was originally setup so that the two motor/motorcontroller/battery systems were completely separate. After ...
1 vote
1 answer
102 views

### Trying to solve a RL circuit by hand but simulator calculates a value I do not understand

I have this circuit. V3 is just a trigger to close the switch, just ignore it. The switch is open for a long time. So, the left part of the circuit is working for a long time and the inductor is ...
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0 votes
2 answers
2k views

### How to calculate time for NiMH batteries to discharge?

I want to use 4 battery cells AA NiMH (or NiCd) 1.2 V, 2600 mAh in order to power up circuit that requires 5 V, 300 mA. I know that fully charged NiMH can provide 1.35 V each, which means 5.4 V in ...
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0 votes
3 answers
452 views

### Can I put Li-ion batteries in series and discharge them at different voltages?

I need to run a pump (drawing 95mA at peak flowrate) at +14V and the rest of my circuit runs on +3.3V. To save on battery costs, I was thinking of purchasing four 18650s at 3.6V 3500mAh per cell and ...
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0 votes
3 answers
2k views

### How to build Li-ion over-discharge protection board

I have an Arduino board with a pump attached to it, and for powering both, I'm using a 18650 battery cell with a DC-DC Boost Converter. I plan to leave it working even when I'm not home, and I know ...
• 511
0 votes
2 answers
207 views

### Ultracapacitor initial voltage drop during discharging

I've been building a test stand for ultracapacitors, with very simple schematic looking like this: simulate this circuit – Schematic created using CircuitLab The resistor on the bottom is to ...
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-1 votes
3 answers
3k views

### Automatically discharging capacitor [closed]

Say I have a capacitor of 100uF connected to 2Volts battery supply (In real circuit, this will be a solar panel exposed in the sun)... After some time, the capacitor will be charged fully with a ...
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-1 votes
1 answer
5k views

### Max discharge rate of Alkaline AA batteries?

I'm in a bit of a tight situation, as I need a new battery pack for an upcoming competition, so I've tried to make my own. I put 7 of these: http://www.amazon.com/Rayovac-Alkaline-AA-Batteries-36-...
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