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Post by Jugglerguy on Jan 22, 2022 16:19:36 GMT -5
I'm struggling to understand how to calculate the number of watts an electric motor uses. I have read here and on many other websites that to calculate watts, you simply multiply volts by amps. Here's where I'm confused: If I multiply 115 volts x .57 amps, I get 65.55 watts but the motor says 36 watts. Also, the Lot-O motor says 2.1/2.5 amps and 60/50 Hz. I think I have that one figured out. I should use 2.1 Hz since I live in the USA and we have 60 hz power, right?
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Post by Jugglerguy on Jan 22, 2022 16:33:53 GMT -5
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Post by knave on Jan 22, 2022 16:44:56 GMT -5
The way Lortone labeled that is very confusing. I’m forced to assume that 36w is the nominal load of a new well oiled tumbler and the .6 Amps is the maximum current the motor can use before thermal protection circuit shuts it off.
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Post by knave on Jan 22, 2022 16:52:32 GMT -5
The actual watts used is the delivered voltage (at the motor or outlet) X the actual amps used. The RLA (rated load amps) on the nameplate is the hardest you can safely work that motor. If there is a SF (service factor) rating, such as 1.15, the motor will continue to operate even if it’s loaded to 115% of the RLA.
For example if you measured .3 Amps on the L1 wire with a clamp style amp meter, and 119 volts, Your watts would be 119 x .3 = 35.7 watts.
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Post by Jugglerguy on Jan 22, 2022 17:06:57 GMT -5
The actual watts used is the delivered voltage (at the motor or outlet) X the actual amps used. The RLA (rated load amps) on the nameplate is the hardest you can safely work that motor. If there is a SF (service factor) rating, such as 1.15, the motor will continue to operate even if it’s loaded to 115% of the RLA. For example if you measured .3 Amps on the L1 wire with a clamp style amp meter, and 119 volts, Your watts would be 119 x .3 = 35.7 watts. Thanks for the help. I've had a lot of people ask how much I spend on electricity lately and I'm trying to figure that out. I read a bunch of threads here, but this wasn't brought up. Was I right about the Lot-O motor being 2.1 amps?
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Wooferhound
Cave Dweller
Lortone QT66 and 3A
Member since December 2016
Posts: 1,423
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Post by Wooferhound on Jan 22, 2022 17:09:35 GMT -5
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Post by Jugglerguy on Jan 22, 2022 18:19:17 GMT -5
I just got one of those in the mail. I haven’t opened it yet. I’m planning a video showing the cost to run various tumblers, but I wanted to do the calculations and then compare them to the results from the Kill A Watt. I thought that would show people how to calculate the cost without buying anything and how it compares to a measured result.
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badrock
starting to shine!
Member since January 2022
Posts: 30
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Post by badrock on Jan 22, 2022 18:57:15 GMT -5
Not the answer to the question, but perhaps pertinent. I've a Lortone 3a (same motor). I've measured the actual watts used at 25 (loaded w/ rocks). My Jackery indicated the same. QT6 = 52 watts. QT12 = 53 watts (converted QT66).
Cost to run: 25 (watts) x 24 (Hours a day) x 30 (days in a month) = 1,800 watts Cost of my electricity is $0.10 per 1,000 watts, therefore $1.80 a month cost to run my Lortone 3a.
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Wooferhound
Cave Dweller
Lortone QT66 and 3A
Member since December 2016
Posts: 1,423
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Post by Wooferhound on Jan 22, 2022 19:11:24 GMT -5
Generally the Watts/Amps listed on any electrical device is somewhat higher than you will ever encounter in Real Life.
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Post by parfive on Jan 22, 2022 20:26:46 GMT -5
When it comes to low-level power consumption, the ol’ 100-watt bulb is a handy comparator, and much more relatable to the average Joe than Olympic swimming pools.
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Post by Jugglerguy on Jan 22, 2022 20:55:02 GMT -5
Not the answer to the question, but perhaps pertinent. I've a Lortone 3a (same motor). I've measured the actual watts used at 25 (loaded w/ rocks). My Jackery indicated the same. QT6 = 52 watts. QT12 = 53 watts (converted QT66). Cost to run: 25 (watts) x 24 (Hours a day) x 30 (days in a month) = 1,800 watts Cost of my electricity is $0.10 per 1,000 watts, therefore $1.80 a month cost to run my Lortone 3a. Thanks, that gives me some numbers to compare my numbers to to see if I'm getting correct readings.
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Post by Jugglerguy on Jan 22, 2022 20:58:24 GMT -5
Here's what I'm getting from my Kill A Watt for my Lortone 33B with two full barrels on it.
122.6 volts 0.39 amps 25.2 Watts 60 hz .51 power factor
Volts x Amps x Power Factor = Watts 122.6 x .39 x .51 = 24.4 That's at least close to the watts calculated by the Kill A Watt. The numbers are fluctuating a bit, so I didn't expect my calculation to come out perfect. I'm going to run it overnight.
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waterboysh
spending too much on rocks
Member since April 2021
Posts: 369
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Post by waterboysh on Jan 22, 2022 23:26:14 GMT -5
I can provide you with some numbers of what my tumblers use. I have a Sense energy monitor and here are some screenshots I took recently. Now that 2021 is over this is something I was planning on looking at myself. Here is my 33A running by itself. It draws about 23W. Here is my 33B running. It's pulling about 25W. It's my understanding they use the same motor, so I'm guessing it's because of the increased load on the motor. Here is my QT6 running by itself. It draws about 50W. You can see the small spike when I turn each on. That's from the inrush current. But that settles down very quickly. The numbers will fluctuate a bit too based on the supply voltage. Mine usually hovers around 123v. Now... how much did running these cost me in 2021? The answer is $106 and it was about 5% of all my electricity usage at 573.8 kWh. A small caveat to this is that I didn't start until the end of March with the 33B and added the other two tumblers over the course of the next 2 months. So to estimate, I'd say that 574 kWh was only 2/3 of a year. So my estimate for a whole year is about 860 kWh, which would cost me $159. For a little perspective, my fridge used 795 kWh last year. I'll try to remember to check out the Lot-o's power meter next time it runs. I'm actually using a smart plug for the tumblers that integrates into Sense and have them running all on the same smart plug. So most of the time I see a single entry for about 97W running. Looking back at the power meter, during the time I ran it last weekend I can see the power fluctuating between about 186W and 190W. So that would be a draw of about 90 - 95W for the Lot-o. Next time I run it I'll unplug the rotary tumblers and look at the graph with just the Lot-o going.
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Post by Jugglerguy on Jan 23, 2022 11:00:11 GMT -5
Thanks, Waterboy. That's helpful to see that what I'm measuring seems to match what you're seeing. I'm still a little confused about why the calculations are not more accurate. I guess theoretical doesn't match real world too well in this case.
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waterboysh
spending too much on rocks
Member since April 2021
Posts: 369
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Post by waterboysh on Feb 9, 2022 9:48:07 GMT -5
I know you already made your video, but for completeness sake, here is the meter for the Lot-o. It had an inrush current draw of about 140W and after a moment settled down to 92W.
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