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Re: Batteries and mains, going solo.

Cross-posted to 2 groups.

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On 2025-09-11 13:09, c186282 wrote:
> On 9/11/25 4:45 AM, Carlos E.R. wrote:
>> On 2025-09-11 03:12, c186282 wrote:
>>> On 9/10/25 8:10 PM, Carlos E.R. wrote:
>>>> On 2025-09-10 23:11, c186282 wrote:
>>>>> On 9/10/25 3:55 PM, Carlos E.R. wrote:
>>>>>> On 2025-09-10 21:35, c186282 wrote:
>>>>>>> On 9/10/25 9:49 AM, Daniel70 wrote:
>>>>>>
>>>>>>
>>>>>>>> REALLY?? If it has NO references, how does it know WHAT *EXACT* 
>>>>>>>> voltage and frequency to produce??
>>>>>>>
>>>>>>>    It's going to be either 50hz or 60hz ... any
>>>>>>>    generating system bought in your area should
>>>>>>>    default to the local frequency. A few may have
>>>>>>>    selector switches. Get it right. You can run
>>>>>>>    a lot of 60hz stuff from 50hz but it's not wise
>>>>>>>    to run 50hz stuff from 60hz - esp if motors
>>>>>>>    and transformers are involved.
>>>>>>
>>>>>> A lot of electronics nowdays will work, they are designed for 
>>>>>> travelling. Computers, USB chargers, etc. Read their documentation 
>>>>>> before travel.
>>>>>
>>>>>    Don't try to run a 50hz air conditioner or fridge
>>>>>    on 60hz though. The motor windings may overheat.
>>>>
>>>> I won't. They don't fit in the cabin luggage allowance.
>>>>
>>>> Although mine are inverter type, they might work.
>>>
>>>    Explain what you mean by "inverter" here ... do
>>>    you feed the things DC ? Do they change AC to DC
>>>    and then cleverly meter that out ?
>>>
>>>    AC->DC ... there is going to be a rectifier in there
>>>    and those often have a 'C' or 'LC' filter to smooth
>>>    out the DC. 50/60 optimized may use different component
>>>    values.
>>
>> I don't have schematics, but the assumption is that they do an AC-DC 
>> conversion, and then they convert back to AC at the variable frequency 
>> wanted for the motor, ie, adjusting its speed.
> 
>    That's just weird and overly-complex ...
> 
>    Straight-up way is to run the fridge compressor from
>    the main, then run it for as long as needed as often
>    as needed. Variable compressor speed ... not sure of
>    any design where that'd be more efficient. The most
>    common compressors these days are 'scroll' design,
>    looks like a spring within a spring. It relies on
>    the viscosity of the refrigerant to work properly.
>    Run the thing at half speed and the refrigerant is
>    gonna tend to 'slip backwards'. The scroll motion
>    and the refrigerant are a "matched system".

I know for a fact that my AC adjusts the rotating speed of the 
compressor. It is a Mitshubishi. You just need to stand outside the 
house, near the compressor, and notice how the sound from the compressor 
changes volume and pitch. If I demand several degrees of temperature 
change, the motor pitch goes up. When the target temperature is reached, 
it goes down, and conversely, the electric power that I measure goes 
down, slowly, from about 1200W to maybe 150W.

In the end, in stable conditions, the compressor turns at a constant 
speed that keeps the space inside at a constant temperature, the one 
that I asked for, exactly compensating the heat losses trough walls and 
heat sources like the computer inside.



>> My AC might have a trifasic motor, or perhaps a brushless DC motor. 
>> The fridge claims to have a linear motor, which I understand is not 
>> rotating, but some kind of piston and an electromagnet moving it 
>> forward and back, at a variable frequency.
> 
>    Piston compressors are quite rare these days - they are
>    more expensive, more little parts. Even thus you also
>    need a proper pressure differential between the high
>    and low pressure sides of the refrigerant loop in order
>    to get good thermodynamic efficiency. You can't just
>    run even a piston compressor at one-tenth speed because
>    you won't get that optimal pressure differential.
> 
>    Review the owners manual or post a link.

Search "LG Linear Inverter fridge", or ask chatgpt to explain them :-)

> 
>    Peltier chips CAN be run on pulsed DC - but they are
>    seriously low-efficiency power-wise. Require just stupid
>    amperage. Tried to build a micro-fridge using those
>    one time ...

They do exist, commercially. For cars. Plug into the car cigarette plug. 
Can be used to heat the food when you arrive at your picnic site :-D

https://www.amazon.es/dp/B0F4Y52V4D/

https://www.amazon.es/dp/B0BX9Q2MH6/

https://es.aliexpress.com/item/1005008678105686.html

> 
>    Well-made piston compressors are, or were, "better"
>    IMHO - could last 30+ years. Alas the quality went
>    down over time and then everybody switched to the
>    scroll type. Did find an ancient Norge in a country
>    store some years back - piston compressor, radiator
>    coil on top. Still worked.
> 
>> I did not say that they will work with either 50 or 60 Hz, but that 
>> they might. Not going to test it!
>>
>> I am looking at the AC user manual, and amazingly there is no specs page.
> 
>    Uh oh ...  :-)
> 
>    There ARE DC refrigerators and A/C units - generally
>    intended for 'recreational vehicles' (or 'caravans' as
>    the Brits call them). Again though the compressor always
>    runs at full speed for x-minutes. SOME might have DC->AC
>    converters inside, but that's a complication. Basically
>    means they want to use some more common/cheaper AC-motor
>    compressor instead of one with a DC motor.
> 
>    Anyway, what you're describing just doesn't seem,
>    well, 'logical', for those sorts of appliances.


-- 
Cheers, Carlos.
ES🇪🇸, EU🇪🇺;

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Re: Real-time OSs (Re: Microsoft Is Abandoning Windows 11 SE) Daniel70 <daniel47@somewhere.someplaceelse> - 2025-09-06 22:41 +1000
  Re: Real-time OSs (Re: Microsoft Is Abandoning Windows 11 SE) "Carlos E.R." <robin_listas@es.invalid> - 2025-09-06 15:41 +0200
    Re: Real-time OSs (Re: Microsoft Is Abandoning Windows 11 SE) Daniel70 <daniel47@somewhere.someplaceelse> - 2025-09-08 00:00 +1000
      Batteries and mains, going solo. "Carlos E.R." <robin_listas@es.invalid> - 2025-09-08 23:17 +0200
        Re: Batteries and mains, going solo. not@telling.you.invalid (Computer Nerd Kev) - 2025-09-09 08:41 +1000
          Re: Batteries and mains, going solo. "Carlos E.R." <robin_listas@es.invalid> - 2025-09-09 02:56 +0200
            Re: Batteries and mains, going solo. c186282 <c186282@nnada.net> - 2025-09-09 04:49 -0400
        Re: Batteries and mains, going solo. Daniel70 <daniel47@somewhere.someplaceelse> - 2025-09-10 22:14 +1000
          Re: Batteries and mains, going solo. "Carlos E.R." <robin_listas@es.invalid> - 2025-09-10 14:18 +0200
            Re: Batteries and mains, going solo. Daniel70 <daniel47@somewhere.someplaceelse> - 2025-09-10 23:49 +1000
              Re: Batteries and mains, going solo. "Carlos E.R." <robin_listas@es.invalid> - 2025-09-10 20:58 +0200
              Re: Batteries and mains, going solo. c186282 <c186282@nnada.net> - 2025-09-10 15:35 -0400
                Re: Batteries and mains, going solo. "Carlos E.R." <robin_listas@es.invalid> - 2025-09-10 21:55 +0200
                Re: Batteries and mains, going solo. c186282 <c186282@nnada.net> - 2025-09-10 17:11 -0400
                Re: Batteries and mains, going solo. "Carlos E.R." <robin_listas@es.invalid> - 2025-09-11 02:10 +0200
                Re: Batteries and mains, going solo. c186282 <c186282@nnada.net> - 2025-09-10 21:12 -0400
                Re: Batteries and mains, going solo. "Carlos E.R." <robin_listas@es.invalid> - 2025-09-11 10:45 +0200
                Re: Batteries and mains, going solo. c186282 <c186282@nnada.net> - 2025-09-11 07:09 -0400
                Re: Batteries and mains, going solo. "Carlos E.R." <robin_listas@es.invalid> - 2025-09-11 19:28 +0200
                Fridge Freezers (was: Re: Batteries and mains, going solo. "Kerr-Mudd, John" <admin@127.0.0.1> - 2025-09-11 21:20 +0100
                Re: Fridge Freezers "Carlos E.R." <robin_listas@es.invalid> - 2025-09-12 00:51 +0200
                Re: Fridge Freezers (was: Re: Batteries and mains, going solo. c186282 <c186282@nnada.net> - 2025-09-12 02:27 -0400
                Re: Fridge Freezers (was: Re: Batteries and mains, going solo. "Kerr-Mudd, John" <admin@127.0.0.1> - 2025-09-12 09:42 +0100
                Re: Fridge Freezers (was: Re: Batteries and mains, going solo. c186282 <c186282@nnada.net> - 2025-09-12 06:26 -0400
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                Re: Batteries and mains, going solo. c186282 <c186282@nnada.net> - 2025-09-12 01:18 -0400
                Re: Batteries and mains, going solo. "Carlos E.R." <robin_listas@es.invalid> - 2025-09-12 12:36 +0200
                Re: Batteries and mains, going solo. Daniel70 <daniel47@somewhere.someplaceelse> - 2025-09-13 19:53 +1000
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                Re: Batteries and mains, going solo. Farley Flud <fflud@gnu.rocks> - 2025-09-13 13:13 +0000
                Re: Batteries and mains, going solo. The Natural Philosopher <tnp@invalid.invalid> - 2025-09-13 17:21 +0100
                Re: Batteries and mains, going solo. Farley Flud <ff@linux.rocks> - 2025-09-13 18:20 +0000
                Re: Batteries and mains, going solo. Daniel70 <daniel47@nomail.afraid.org> - 2025-09-14 20:06 +1000
                Re: Batteries and mains, going solo. The Natural Philosopher <tnp@invalid.invalid> - 2025-09-14 17:45 +0100
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                Re: Batteries and mains, going solo. The Natural Philosopher <tnp@invalid.invalid> - 2025-09-14 17:42 +0100
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                Re: Batteries and mains, going solo. Mark Lloyd <not.email@all.invalid> - 2025-09-11 18:20 +0000
                Re: Batteries and mains, going solo. c186282 <c186282@nnada.net> - 2025-09-12 02:14 -0400
              Re: Batteries and mains, going solo. The Natural Philosopher <tnp@invalid.invalid> - 2025-09-11 10:45 +0100
                Re: Batteries and mains, going solo. Daniel70 <daniel47@somewhere.someplaceelse> - 2025-09-11 21:15 +1000
                Re: Batteries and mains, going solo. Graham J <nobody@nowhere.co.uk> - 2025-09-11 13:52 +0100
                Re: Batteries and mains, going solo. The Natural Philosopher <tnp@invalid.invalid> - 2025-09-11 15:17 +0100
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                Re: Batteries and mains, going solo. Lars Poulsen <lars@cleo.beagle-ears.com> - 2025-09-13 14:05 +0000
                Re: Batteries and mains, going solo. Daniel70 <daniel47@nomail.afraid.org> - 2025-09-14 20:14 +1000
                Re: Batteries and mains, going solo. "Carlos E.R." <robin_listas@es.invalid> - 2025-09-11 19:31 +0200
                Re: Batteries and mains, going solo. c186282 <c186282@nnada.net> - 2025-09-12 01:31 -0400
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                Re: Batteries and mains, going solo. The Natural Philosopher <tnp@invalid.invalid> - 2025-09-12 07:21 +0100
                Re: Batteries and mains, going solo. "Carlos E.R." <robin_listas@es.invalid> - 2025-09-12 12:40 +0200
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              Re: Batteries and mains, going solo. c186282 <c186282@nnada.net> - 2025-09-12 10:43 -0400
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