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Questions tagged [watts]

The unit of measurement and SI unit for power, named after James Watt. It is equivalent to energy flow per second or Joules/Second. In electrical terms \$ W = IR = I^2 * R = V^2/R \$

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45 views

LiPo vs NiMh time to failure [duplicate]

If I have (numbers for NiMh are estimates not exact values): LiPo 12.8V, 19.2Ah, and 245.8Whr NiMh 12V, 30Ah, and 360Whr (Freedom DF300 Stationary Battery has a capacity of 30Ah for discharge in ...
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2answers
41 views

Wireless fast charging in car

For my phone I want to wirelessly charge my devices as fast as possible using the cigaret socket (Automobile auxiliary power outlet). I bought a wireless charging pad which on the back states. ...
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0answers
57 views

Why crypto ASIC miners have high wattage rating? [closed]

I was going through the specification of few crypto ASIC miner having 55 Th/s and noticed that the wattage above 3500W . The power supply is converting 230V AC to 12VDC to 3 chip boards.And the chip ...
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1answer
43 views

Accuracy on wattage measurement: multimeter+formula or wattmeter [closed]

Which tool that have more accuracy on measurement of a resistive load ac sinusoidal wave?
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3answers
88 views

How will I know the power [dissipation] of resistor when buying resistors?

It is very basic question for many people. It is very easy to predict the resistance of a resistor with multimeter, but sometimes it comes with resistors which are slightly larger in size, such as, ...
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2answers
77 views

why volt is needed for calculate watt? [closed]

hello i dont sure what is the difference between voltage ampere and watts. voltage is only the potential difference between points high voltage will not cause to the electrons to move faster so why ...
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1answer
100 views

How to find how many Amperes does a equipment use? [closed]

In the specification of this miner https://www.asicminervalue.com/miners/bitmain/antminer-s9j-14-5th it says it uses 1350W power with ...
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1answer
72 views

At what point a battery becomes a load

This has probably been asked before but I don't know how to search for it. In a circuit where there are a battery and a variable power supply, what conditions have to be met in order for the battery ...
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2answers
85 views

calculating Power

I wanted to ask, if I have a electrical component with a power rating of let's say 5W does this mean it would dissapate 10W after 2 hours and 15 W after 3 hours?? or is it correct to say it dissapates ...
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1answer
45 views

Wheelchair battery life calculation

Apologies because I'm sure this is an incredibly basic question and I've tried to work out the answer myself but I'm getting nowhere with it! I'm looking to get a powered trike attachment from my ...
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2answers
57 views

Why can a charger handle more watts at a higher voltage?

Why is it that my charger that has a rating of 100-240 volts and 1.3 amps can handle/input more watts at a higher voltage when doing the formula watts=volts x amps? In addition, why can't it, at a ...
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34 views

24V LED Strip Circuit - Switch, Breaker & Wiring Size Requirement

I am running a long LED strip (24V, 21 meter, 0.6A per meter, so technically 13A). The 24V PSU supplying power to the strips is to be connected to a switch that is rated 240V, 10A & 2400W. ...
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1answer
392 views

An overseas company is making a machine for me and they need to know whether I want 1,2 or 3 phase and what voltage

I'm in Quebec and the company making the machine is in China. The machine is an industrial sized T-Shirt sublimation machine that does two sided printing. So there's a large heated plate that is ...
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3answers
557 views

What does the power rating of 10W mean?

When hair clippers or similar appliances are rated at, for example, 10W, does that mean 10W per hour or second? I'm trying to determine power of various hair clippers.
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70 views

BLDC Motor max load

Hi i have a BLDC moter https://www.banggood.com/350W-48V-DC-Brushless-Motor-Geared-Ebike-Tricycle-Kit-Engine-Electric-Scooter-p-1419702.html?akmClientCountry=NL&rmmds=cart_middle_products&...
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1answer
51 views

Wattage in US vs AU/EU household appliances

This oven is listed in both the US and Australia. You can see that it's the exact same model (BOV845). Yet if you open the specifications, the only difference is that the US model uses 1800 Watts ...
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1answer
40 views

Batteries Spike in Watts and Amps Pulled with less than 50% Life

To give a background on this, I have been running tests to determine the actual lifespan of a 3 cell pack of some Samsung 18650s and Tesla 2170s at just above freezing. The Samsungs are INR18650-35E ...
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2answers
78 views

If a 110 volt motor asks for 4W does that mean I will have to change the wall power? [closed]

I am new to electronics like motors so help on how to set this up would be awesome.
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1answer
88 views

Ammeter scale, not sure what my amp reading is

I have a basic multi-meter that I am using to measure amp on a load. I am trying to figure out how much amps my small entertainment system draws. (LCD TV, PC, speakers.) I want to build a small DC ...
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1answer
75 views

How to replace push buttons on an intercom?

This is the intercom panel in my apartment, it's 30+ years old and I want to give it a face lift. The push-buttons are momentary, and I want to replace them using modern ones like these, but I'm not ...
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1answer
80 views

built in charge controllers take amps they need?

Many devices have built in charge controllers that stop charging when battery is at 100%. I read several places that you can charge devices with the manufacturers recommended voltage and that higher ...
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3answers
622 views

heat dissipation in watts of equipment in a box

Here is the situation, some electrical equipment will be in low ambient temperatures and I need to make it warmer so that there is no damage to it. I want to calculate how much power in watts is ...
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5answers
78 views

When charging rechargable battery, should we care about watts and ignore voltage and current?

I know this might be a silly question, but it's from a beginner. Let's say I want to charge a rechargable lithium-ion battery, so when I charge it should I only check the watts and ignore voltage and ...
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1answer
74 views

How can a 12V 80Ah Battery be 1800W? Shouldn't it be 960W?

How can a 12V 80Ah Battery be 1800W? Shouldn't it be 960W? I was looking for 12V 80Ah Deep Cycle Batteries on Amazon and most of them were 1800W. Like this one: https://www.amazon.com/Cycle-Battery-...
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1answer
59 views

Transistor Inverter - when does excessive small wattage become a problem?

I'm trying to choose the best values of resistors given the stock I have so that I can deliver sufficient power and current to an HM-TRP radio module. In this circuit, I used the 100K resistor ...
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1answer
168 views

What defines Volts, Amps, Watts and mAh?

My current understanding is as follows: Volts: Speed of electron flowing. Amps : Number of electrons flowing. Watts: Amps x Volts measured for "some" time. mAh: Very confused to come up with ...
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1answer
192 views

How does a Hall-based wattmeter work?

I read about the Hall effect and understand its usage in sensors like speedometers, but I also read it can be used as a wattmeter. How can it happen? In order to calculate power (P) we need to ...
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2answers
70 views

Soldering station: power confusion

i wanted to ask what the different power/watt indictors for a soldering station actually mean in terms of the performance of the station or whether the number is just some marketing term. Some ...
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5answers
140 views

A basic question about amps, watts, and charging batteries

Why do we speak of watts (and not amps) when we refer, for example, to the "7.5W Wireless Charger for iPhones," but when we talk about cord-based USB charging, the specs typically refer to amps (and ...
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2answers
34 views

Lower wattage of IR bulbs permanently

I have two 90w/12v infrared IR bulbs which is put into a r7s sockets. From thes socket goes in total four wires which is connected to our power supply. We have set two of the wires in serial so they ...
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2answers
95 views

Why does curling a wire decrease its amperage/wattage? [duplicate]

I picked up an extension cord today, and I noticed that it had a different value for its wattage and its ampage, based on whether the cord is wound around its base or not. (I apologize that the ...
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1answer
61 views

how do LED controllers work

I’m trying to find out if a device only draws the watts it needs to run or if it takes all available For example I have led light that’s says max 0,75 watts and the led controller says output 144 ...
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2answers
68 views

Electrical Power Question

I am trying to compare watts exiting the battery vs watts being consumed by the bulb. I have set up a test circuit shown below. Should not A-B watts match C-D watts?? Sorry for such a basic ...
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1answer
61 views

Are watts consumed in wireless electricity? [closed]

If I put a transistor on a coil of wire connected to a 120v AC circuit, and made it so my toaster was now wirelessly powered, if I turned the toaster on would it consume watts that are able to be ...
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2answers
166 views

Why does my phone charger consume more electricity (watts) when delivering less amps (slower charging)? [closed]

As far as I could understand, the charging speed is measured in amps. Like, if I use Ampere, it will tell that it charges in 2.5 amps, or 1.5 amps. I hope I got this right. Amps is the only ...
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2answers
127 views

How can I measure an induction cooker’s power with an oscilloscope?

I have to measure the current and voltage of a coil with an oscilloscope. In this case, does P Watt = Irms*Vrms? The induction cooker writes that the maximum Watts is 1.2K, but I measure it over 1.2 ...
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1answer
68 views

Is it okay to run a Mercury Vapor Lamp of lower wattage (100/150/175W) on a 400W MHL/MVL ballast? Also can a 60Hz ballast be used in 50Hz?

So, I have this RAB BMHH400PSQ Metal Halide Pulse Start Ballast 400W ,M135/M155 MULTI TAP 120-277V with me. Since the MVL are being phased out it has become quite difficult to get a ballast for one of ...
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2answers
755 views

Alternatives to High Wattage Resistors? (Do multiple low-wattage resistors equal a single higher wattage resistor?)

I am a beginner, so I may have made a horrible mistake in my diagram, but I am trying to learn. According as I have figured it, I am having an issue wherein I need a resistor rated for a minimum of ...
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1answer
60 views

How can I interpret the readings of a USB voltage tester considering the input voltage is 5V and I am charging a 3.7V battery?

I have this USB voltage tester that I place between my usb wall charger and a USB charging cable. This device gives me the total current that went through over a period of time. Let's say after 2.5h ...
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1answer
2k views

Motor current consumption and power do not match

I am working on a design and need to calculate the energy consumption of this motor: https://www.maxonmotor.com/medias/sys_master/root/8825428410398/17-EN-256.pdf. (Part No. 339252) The ...
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1answer
102 views

How to properly read Watt of a bulb power?

I'm confused about reading the terms Watt, Wh, and Ws of bulbs. Here is the quoted text taken from an electrical book that I'm currently reading on : Now I'm take out some points from the remarks ...
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1answer
60 views

A question about my refrigerator [closed]

it's written on my refrigerator 500watts.. I want to know how much it consume watts per month. let's consider that the compressor of the refrigerator works 10 hrs per day.
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1answer
731 views

12 Volt vs a 24 Volt Motor

I have read that using a higher voltage motor would need less current to get the same power. I understand that P = IV and how that works. My question is if the 24 V motor would get half of the current,...
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1answer
37 views

why does a potencial coil in wattmetter influences the pointer rotation

can somebody tell me, why does a potential coil in wattmetter influences the pointer rotation. if the ideal potential coil doesn't have current, it would not generate a magnetic field and it would not ...
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2answers
756 views

12 v watt heater with nichrome coil [closed]

i am new here. First of all I am sorry for my bad english. I want a help from those who know about nichrome heater coil. I want to make a 12v dc incubator using nichrome wire as heating element, all ...
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1answer
32 views

What wattage should I use for a switching adapter?

I have a bad switching adapter. It has a DC output of 14.5V 2.48A Max. I can't find a match anywhere. I think a 3.0 Max will work, but I don't know the wattage. The replacements I've found are 29W, ...
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1answer
100 views

Step up voltage Transformer for more watt?

Using generator in mountain or underground tunnel location, construction workers from portable generator gets maximum: AC Output: 220volt as 200 to 250watt Now, they need to use a machine for ...
0
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1answer
109 views

Does a 5w LED lamp require 5w/per hour to run ?

Does a 5w LED lamp require 5w/per hour to run ? eg. would 200 x 5w LED lamps running for 1 hour would require 1kwhr of electricity. Or is the 5w related to some other time scale ?
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1answer
2k views

How many watts does tweeter needs

I have a speaker with the following specs: Max. power - 600W Impedance - 4~8 Ohm Freq. response - 45Hz-20KHz Sensitivity - 98dB/W/M The tweeter of the right speaker is not working so i want to ...
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0answers
191 views

How can I measure the power given to a USB WiFi adapter's antenna in dBm or mW?

I have an Alfa AWUS036ACH USB WiFi adapter, and would like to know how much power is being given to the antennas (in dBm or mW). The Amazon link to it is here: https://www.amazon.com/Long-Range-Dual-...