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 limiting my BLDC Motor power Output?
I am using a BLDC 3 phase hub motor and recently installed a motor controller rated for 3000watt (I originally had a 1200Watt controller installed).
The motor is rated for 500w nominal 800w peak but ...
6
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3answers
968 views
Why is there such a large difference in efficiency in these two boost converter configurations?
Here is the datasheet
I realize that the converter has to "work harder" to boost a voltage from 2.8V-6V to 48V than it does from 8V-38V to 48V, but I'm curious why there's such a significant drop in ...
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0answers
100 views
How to active limit the current from a DC source
I have a source with variable power output during the time because it is shared with another devices and this source has not enough power to feed my load (a battery charger for a 1 cell 4.2V lipo) so ...
2
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0answers
59 views
Designing MOSFET bridge rectifiers for high voltages
I've been looking into MOSFET bridge rectifiers, also known as "zero IQ" rectifiers, as a replacement for traditional diode-based bridge rectifiers.
Here's a simple example:
The benefit, of course, ...
2
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2answers
37 views
How does efficiency of transformer change with respect to primary voltage?
Suppose we have a non-ideal transformer such that secondary load is fixed and we change the voltage applied to the primary side. How does efficiency change with respect to primary voltage? I know ...
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3answers
1k views
Why do LED headlamp bulbs need active cooling?
I decided to install LED headlamp bulbs in my car in the hope that I can avoid replacing bulbs every year. I was quite surprised to find that I can't fit replacement bulbs in my car due to the bulbs ...
34
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3answers
6k views
Computer power supplies usually have higher efficiency on 230V than on 115V. Why?
As seen here in the example, this particular power supply (and most others too) has higher efficiency when running on 230V. Given that computer power supplies are usually required to output a ...
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1answer
26 views
Efficiency of induced power
This is a very basic question which I can’t quite wrap my head around. Say you have a wire/coil in a magnetic field in such a way that if you apply a current in the wire it will move. So you charge up ...
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1answer
49 views
Boost converter efficiency
I simulated a boost converter on LTspice and have measured the steady-state output power to be 80.49 W and the average power drawn out of the input source during steady-state operation of the ...
0
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1answer
95 views
Are permanent-magnet motors equally (in)efficient as motors vs. as generators?
Given a permanent-magnet motor with an efficiency of 80% that converts 100W electrical input power into 80W mechanical output power, would the motor have the same efficiency if used as a generator?
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1answer
47 views
Coordination of mechanical and electrical power in electric drives
I want to ask a question to respected specialists in electric drives.
It is known that the mechanical power of an electric motor is determined by a simple formula:
\${P_{mech}}= M {\omega}\$;
...
0
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1answer
27 views
Boost Voltage before Regulating or vice versa
I have an input voltage from a 3S battery from 7.4V to 11.1V and I need to regulate / boost it to 5V and 12V. So what is more efficient or what is used in industry
Regulate the voltage to 5V with e.g....
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1answer
22 views
Efficiency Test of Permanent Magnet (PM) Motor With Variac&Fixed Resistance
We have a 3-phase permanent magnet motor and want to test its efficiency in generator mode.
We can give a mechanical input power with an external motor (torque meter and tachometer installed) and we ...
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1answer
39 views
Understanding of torque constant and efficiency of a permanent magnet motor from datasheet
I am trying to understand the efficiency of the following permanent magnet synchronous motor Motor Datasheet (note we are using the medium voltage model), and its relationship with the input voltages ...
0
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3answers
125 views
Running an electric motor beyond its ratings
I ordered a 36V 500W brushed DC motor but unfortunately a 24V one came. I'm faced with the dilemma of returning it and waiting for a month before getting a refund, then ordering a new one and waiting ...
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1answer
49 views
Are there any modern tradeoffs that come with designing more efficient DC-DC switching power converters?
Are there common metrics that usually degrade (ex. ramp time, line/load regulation, low-load efficiency) when pursuing more efficient designs, especially for isolated converters?
If you saw a new ...
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1answer
53 views
Headphone sensitivity/efficiency
Most commercial headphones are advertised to have sensitivity greater than 90 dB/mW. But to my understanding, even with 100% efficiency that's not possible (if we use 10 log (I/I0) where I = 1 mW, we ...
6
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3answers
797 views
Heatsink on underside of PCB
I have prototyped some DC-DC converter modules, and they work well. However due to size, I don't have a huge amount of copper pour for them to dissipate their heat. I have used 2oz copper but the ...
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3answers
91 views
The relationship between power, heat and efficiency
I've been thinking about this conundrum.
Given we use joules to move a metal block over a surface, we do work.
So imagine a motor, that spins and pulls a string, moving said metal block over one ...
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4answers
99 views
Do smaller transistors improve computational efficiency because they decrease the duration of signal transfer?
There has been a massive improvement of computational power of computers per $ over time. As far as I understand, this has been driven almost completely by the massive increase in transistors per ...
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2answers
246 views
How to efficiently read a battery voltage level with ADC
There is a circuit powered by a battery (3V button cell) and another circuit with a microcontroller (Attiny85 in my case) reading perfectly the battery level (through ADC3 pin) each 5 minutes interval....
2
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2answers
285 views
Class A Audio Amp - Improving Efficiency With A Mosfet CCS
I'm designing a class A audio amplifier but am struggling with the efficiency of my circuit.
I know of 'push-pull' Class A designs, but only want to use a single output mosfet.
I would like to hit a ...
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0answers
50 views
Astable multivibrator inverter
I'm new to electronics and trying to make an astable multivibrator oscillator. The PSpice simulation doesn't work (it says netlist error when I place a mosfet or a diode) and I get a really low ...
2
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1answer
177 views
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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2answers
82 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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1answer
109 views
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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2answers
51 views
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
...
4
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2answers
375 views
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 ...
0
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3answers
110 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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2answers
2k 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....
0
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1answer
73 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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2answers
948 views
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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2answers
123 views
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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3answers
164 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 ...
2
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3answers
121 views
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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2answers
135 views
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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0answers
31 views
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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1answer
43 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 ...
0
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3answers
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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2answers
33 views
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 ...
0
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2answers
359 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, ...
2
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3answers
114 views
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 ...
0
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2answers
152 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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1answer
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 ...
6
votes
2answers
314 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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5answers
9k views
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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0answers
79 views
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 ...
0
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1answer
61 views
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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1answer
82 views
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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2answers
86 views
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 - ...
