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Questions tagged [efficiency]

A measure of the overall effectiveness of a system. For example, in power conversion, it would be the ratio of output power to input power.

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What is the equation for mechanical efficiency of a 3 phase induction motor?

I know that mechanical efficiency is n= power output/power input, but I don't know how to find each of those. I have to find the efficiency at full load running speed. I was only given mechanical ...
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59 views

Energy lost in in Peltier device?

Suppose I power a Peltier device to heat up/cool down some water. Then I later use the same Peltier device, in reverse, to convert the separated heat energy back into electricity. I have read ...
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Aluminum Electrolytic Capacitor - current, power, efficiency

How to find out the efficiency of an aluminum electrolytic capacitor like this one. How to find out resistance of such a cap in order to calculate the time it takes for it to charge up or discharge? ...
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Determine efficiency, voltage, current from motor characteristic curves

I would to identify efficiency, voltage, current for a particular Brush less DC motor in our lab given characteristic curves. Electrical specifications are The operating conditions are ...
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How to measure DC motor (used as generator) efficiency using homebrew methods?

Background I'll be making a "micro thermal power station" in the single-digit watt range at home (one-off, educational project. Bear with me). A heat source, likely ethanol, will cause a stirling ...
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93 views

Which is more efficient: A much larger than needed step-down voltage converter, or one rated closer to the actual load?

I'm designing a custom audio system for my electric motorized pedicab. The motor of my cab runs on a 48 V 33 Ah battery, and I have planned to use a 48 V to 12 V step-down converter to simultaneously ...
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184 views

5V vs 12V addressable LED efficiency

Despite hours of googling, I could not come to clear understanding how efficiency of 5V addressable LEDs compare to their 12V counterparts. If 5V is supplied to WS2812, and the red LED only needs 2....
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35 views

PWM phase voltage and current measurement for power consumption calculation for a BLDC MOTOR

I have been trying to log both voltage and current from the battery of an electric two wheeler for finding out efficiency at inverter, battery level.
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Relationship Between Number of Coil Turns in DC Motor and the Efficiency of Energy Retrieval From Regenerative Braking

When learning about regenerative braking, I began to ponder as to what the relationship between the number of turns in the coil of a DC motor is to the efficiency of kinetic energy retrieval from the ...
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electronically efficient breadboard wiring

I have checked stachexhange for my answer, but no luck. I hope I can be helped here. I am building ben eater's 8-bit, and have a general question about wiring: Is it better (less impedance/resistance)...
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93 views

Are activated open-collector and open-drain circuits wasting energy?

Consider the following reference circuit for a 6N137 optocoupler. My understanding is that this circuit uses a pull-up resistor on the output node so when the optocoupler led is activated, the ...
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Why is power factor such a meaningful quantity?

In my current electrical engineering course the concept of power factor has been a large topic, defined as the ratio of real power to apparent power. It is a measure of resistive power consumption in ...
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How does the power efficiency of an appliance compare using 12V DC or 240V AC with an inverter?

With an off-grid system, if an appliance supports powering via both 12V DC and 240V AC, is there any difference with the power efficiency of either method excluding the draw of an inverter used to ...
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Display Design - would combining OLED with a white source be more efficient?

To be clear, I'm not an electrical engineer, nor do I claim complete knowledge of how displays work. However, I have done research into displays (televisions, computer monitors, AMOLED phone screens)...
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32 views

led SMPS converter

Which type of converter is best for an LED light for getting better efficiency and high colour rendering index? We want to design a converter up to 80 Watts which gives indirect lighting and less ...
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72 views

Portable electronic musical instrument: energy from pressing keys, no batteries: feasible? [closed]

on one hand electronic musical instruments are very nice (lot of features: change tonality, change timbre, small number of mechanically breakable parts ), on the other hand they need external power ...
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Pros and cons of centralised vs decentralised power deliver for small devices

How does compare using one power supply for multiple devices vs each device having its own - regarding efficiency eg. power consumption? Model situation: Home automation using low power devices such ...
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184 views

Capacitor charging efficiency with a constant power source

I have a question. It is easy to derive the efficiency for loading a capacitor from a constant voltage or a constant current source, basically because exponential functions and constants are very, ...
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Would I get a better lumen output and improved thermal characteristics for the same wattage if I get a higher rated LED? [closed]

I'm planning on building a bright DIY high CRI LED video/photo floodlight out of the following components and considerations: High-power Neutral White (4000K?) LED rated at 95 CRI No add-on lens so I ...
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149 views

Ohms law and LED driver efficiency? How can this possible be true?

I am having a meltdown with a Chinese supplier at the moment and hope dearly that someone can help. I have an LED driver that is in my mind 28.8W. The output of the driver is 48 V @ 600 mA (48 V x 0....
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27 views

High energy efficiency through transformers

We are about to build a large facility, using lots of electricity. The facility is being built in module form, which are copies of one another. We are unsure of whether the energy efficiency will be ...
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146 views

Do electric motors have the same efficiency when operating as generators?

Its in the title. I'm just curious and it turns out that either this is such a stupid question that no one has bothered to answer it, or i'm just not good at googling today. I guess I'm thinking ...
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How could have Banksy kept an RF receiver running for 12 years? [closed]

I'm talking about Banksy's "Girl with balloon" painting that shredded itself at auction. I think the general consensus is that he didn't, and that it was set up before the auction (or a couple years ...
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Capacitive discharge excess being used for battery recharging

I am currently designing a circuit similar to a cattle prod that is intended to be attached to a drone. The cattle prod is powered by a lithium-ion battery, charging up a capacitor and then quickly ...
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1answer
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Spice model search with advanced sorting functionality

Does anyone know of a search engine like Mouser/Digikey where you can narrow down parts based on voltage/package type/etc., but exclude all results without PSpice models? Unless I'm doing it all wrong,...
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Would it be energy efficient for phones to include actual GPS chip? [closed]

None of the smartphones today have dedicated GPS chips in them, they only have a GPS capability that stems from byproduct features of the modem chips. Because of that, the GPS capability is very ...
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Waste heat in battery pack - large pack vs small pack?

Are larger battery packs more efficient than smaller battery packs due to "resistance in parallel" rule, assuming eveything else being the same? As an example let's consider two 48V battery packs - ...
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75 views

Dell power adapter does not get warm? [closed]

Usually I notice that power adapters get warm whether they are being used to power a device or not. The rectangular Dell computer power adapters, however, do not seem to get warm unless they are ...
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396 views

MOSFET vs. relay power efficiency

Newbie question here. I am putting together a remote switching box for power circuits aboard a yacht. The design is for a central Raspberry pi to send orders to a few boxes, each controlling a number ...
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211 views

Confusing peltier efficiency COP/Volts and COP/Amps graphs question

Is peltier efficiency (COP) based on current and not voltage and could I have any voltage I want and get a high COP if I limit current? Whats confusing is that one graph shows efficiency based on ...
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109 views

Smartphone internal charging circuit type and efficiency

USB usually provides 5V (or even more, for example 9V with Qualcomm Quickcharge) and the phones contain a single li-ion cell with 3.5-4.3V, so there must be some dc-dc converter in between. I wonder ...
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Is there a Semisynchronous Buck Topology which mixes the advantages & disadvantages of both?

I was looking at "What is the purpose of using MOSFET instead of free-wheeling diode in Buck topology?" and the referenced PDF which discusses the trade-offs between a traditional asynchronous Buck ...
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Rated vs. actual power usage of a linear fluorescent lamp

After having some power issues, I've decided to investigate the largest power drains in our company, and I've arrived at a realization that 128 lights adds up to a lot of power (and that's not even ...
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Efficient electronics components [closed]

Imagine budget is not an issue and you are asked to design the most efficient circuit. With efficient, I mean that the power used to perform the functions is used solely for that and is not dissipated ...
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116 views

Will battery last longer with larger capacity but lower efficiency (high V through LDO) or vice versa?

Given a simple circuit of a draw around 28mA (when supplied 3.3v). I'm trying to maximize run time on a battery, but working with what I've got on hand... I have the following batteries: 5000mAh 3S ...
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824 views

Square wave to DC voltage with passive components

Good day, I have a design challenge that I have been thinking about. Is there a passive and inexpensive system that I can get a square wave (frequency not decided yet, but less than 8MHz) that will ...
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107 views

power efficiency's definition

Power Efficiency is defined as output power/input power, right? And there are a little bit different definition of power efficiency ...output power/(output power+power loss). Is these mean same ...
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75 views

Wireless power transfer efficiency calculation

So I'm looking into retrofitting a Qi transmit eval and receive eval kit with coils of a larger diameter than the stock ones, then looking at what playing with the separation will afford me for my ...
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3answers
257 views

How to estimate Li Ion Battery SOC?

In a simple model of a renewable energy system, I have a residential inverer and Lithium ion battery system with a round-trip efficiency (for inverter and battery, i.e. ac to ac) of 89% (at 25 degrees ...
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1answer
208 views

What is the most efficient 3-phase to single-phase AC transformer for a home grid

So a friend of mine is getting electrical power installed for an urban site he bought, and I'm just trying to be a good friend by looking into this. The company doing the installation recommended he ...
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1answer
2k views

Laptop battery and adapter voltage ratings

Considering a 4-cell (laptop) lithium-ion battery, the cell voltages add (since they are in series) to 3.7 V * 4 = 14.8 V. However, the adapter says that it has a 19.5 V DC output. I want to know why ...
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1answer
42 views

Star rating of electrical appliances like AC / fridge

What distinguishes a 2-star rated AC/fridge from the one rated 5-star? What exactly is the technical reason for the difference in their efficiencies? Is it the compressor technology / the wiring / ...
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526 views

Use MOSFET series resistor instead of shunt for current measurement

If I have a setup where a N MOSFET drives a heavy inductive load (say, 25A peak), can I use the MOSFET's internal resistance to measure said current the same way I would use a shunt resistor? The ...
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43 views

How to manage solar panel as backup power source

I have a 12V PC cooling fan (Evercool PWR-1225H12B) that will run on a 12V regulated supply. Said supply is on a 12 hour daily timer. In addition to the timed supply, I want to have a solar panel as a ...
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4answers
308 views

Is it possible to use a heatsink without a peltier plate?

At the moment I am working on a project which implies LEDs for street lighting. I need to dissipate around 24 W of heat. In order to do so, I calculated how much heat is dissipated into the air, and ...
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1k views

How can a low efficiency antenna be used for receiving but not for transmitting?

For the reciprocity theorem, if an antenna has a low efficiency in transmission, it has the same efficiency when receiving. In literature, it is usually said that one shouldn't use a low-efficiency ...
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280 views

Does the source impedance of DC-AC converter always represent losses?

This is a fundamental theoretical question about power and efficiency of AC voltage source with very low output impedance, for example, a DC-AC converter; H-bridge converter or class E amplifier. MY ...
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113 views

What value to use to find complex impedance of a motor?

Output of motor is 3000 W with efficiency of 0.8, so The input power is 3750 W. when I want to find the complex impedance of the motor Z = X + jY i get fail answer when I use P = 3750 W to calculate ...
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The relation about FOM and power extraction improvement

I saw some paper,their comparison is FOM or Power Extraction Improvement(called PEI here),and they are related,PEI=FOM*100,when FOM*100,the PEI value will usually bigger than 100%,take 126% or 425% ...
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The explanation of MPPT and its main function

I think the main function of MPPT is to find the max output power for us to let the power efficiency become the MAX. However,i am still not quite understand MPPT.Is MPPT a schematic or an algorithm?...