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Green Building Bible, Fourth Edition
Green Building Bible, fourth edition (both books)
These two books are the perfect starting place to help you get to grips with one of the most vitally important aspects of our society - our homes and living environment.

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    • CommentAuthorrevor
    • CommentTimeOct 1st 2024
     
    I have a portable battery "power station" a handy piece of kit and have not really assessed it properly for the claims it makes until this last week or so. This what I wrote to customer service. I have not includes the make.

    "I have got a ????? bought back end of last year.

    I have used it sporadically to use in power cuts and a shed with no
    power and found it very useful.

    However have just started using it for an LED panel to grow cress and
    other micro greens and realise I am not getting the full spec.

    The LED light is 35 W but getting 11/12 hours from it display shows
    12hrs power when unit fully charged and showing 100% when unit is fully
    charged.

    So effectively 420 w not 768w that is claimed."

    This is response I got and do not know what make of it.

    "Thank you for contacting Customer Service Centre.
    You say the problem is caused by a conversion rate issue. When the power station is powering less powerful appliances, the output conversion rate is lower,
    The battery unit provides 35W at about 50-60%, so the usage time will be less. If the appliances used are more powerful, the conversion rate can reach 80%-90%, so the usage time will not be in doubt."

    To me it makes no sense it is akin to saying that you can get more mileage out of an EV battery if you drive it hard but actually having a light foot give you more.
    Anybody understand the response I got.
    •  
      CommentAuthordjh
    • CommentTimeOct 1st 2024
     
    Well, I think I understand what they're saying. The power converter that forms part of the device is most efficient when driven in one particular set of conditions (at full output) and less efficient in other conditons (partial power as you are doing). Without knowing more about the device I couldn't say whether that is plausible or reasonable, nor what their specs and/or warranty have to say about it. It's certainly possible though.

    It all depends on the design of the device. You can't generalise from your experience of an EV to something else.
  1.  
    I agree with djh.
    The unit will have batteries which output DC this will need to be converted to 230AC and that conversion will have a cost (efficiency) and the circuit will be tuned to a certain condition, move way from that condition and the efficiency will suffer. Just IMO

    If the unit has a DC output if you can get LEDs that run at that voltage output then you bypass the conversion and avoid the conversion losses.
    • CommentAuthorrevor
    • CommentTimeOct 2nd 2024
     
    Posted By: djhIt all depends on the design of the device. You can't generalise from your experience of an EV to something else.


    Valid point maybe the solar battery would have been a better example. Or my other power station which is a bigger unit designed and made in Germany (and lot more expensive.) does not exhibit the same characteristics as the cheaper one that I was querying. As usual you get what you pay for.

    Posted By: Peter_in_HungaryIf the unit has a DC output if you can get LEDs that run at that voltage output then you bypass the conversion and avoid the conversion losses.


    Good point except my panels are 40v and designed for growing so could not use them.

    Had further response from manufacturer which confirms what you guys are saying and acknowledging that they should mention the efficiency reduction in thier literature.

    "Ordinary batteries without control management modules are powered directly from DC, they have no need for power consumption themselves and no inverter/rectifier, so self loss is almost negligible and conversion is close to 100%.
    Our power stations have other control modules in addition to the batteries themselves, which consume power for settings and functions during battery operation, which also results in the occurrence of conversion losses.
    We will submit this comment to the web/business team so that they can add this necessary information to the web/user manual.
    Thank you for your support and understanding."
    • CommentAuthorphiledge
    • CommentTimeOct 2nd 2024
     
    You could validate their claims by applying whatever the rated full load is and see how many wh you get out of it.
    •  
      CommentAuthordjh
    • CommentTimeOct 2nd 2024
     
    Posted By: revormaybe the solar battery would have been a better example. Or my other power station
    They would just be other examples, probably equally irrelevant. You can't generalise was my point.
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