To: rsgb_lf_group@blacksheep.org
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From: =?UTF-8?Q?Wolfgang_B=c3=bcscher?= <dl4yhf@freenet.de>
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Date: Tue, 19 Mar 2019 08:54:22 +0100
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Subject: Re: LF/VLF: QRO in portable experiments by using LiFePo4 accus from
 China?
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Hi Stefan,

As I understand the offer from your last link, they sell "recycled 
bicycle" batteries (?? - with 12 volts - ??) that once had 100 Ah when 
they were, with a remaining capacity of 40 Ah (as shown in one of the 
ads as "item condition") for use as solar power buffer, where the 
degraded performance doesn't matter. But I wouldn't bet on the internal 
cell resistance, i.e. voltage drop under heavy load...

73,
   Wolf .

On 18.03.2019 17:20, DK7FC wrote:
> VLF,
>
> After a few months of using my 12V/120Ah LiFePo4 accu 
> (https://www.robur-akku.de/p/lifepo4-akku-12-volt-120-ah) i am really 
> happy with the performance!
>
> During an experiment at the ground loop i'm tracking the antenna 
> current, see an example in the attachment. Since the feed point 
> resistance is constant, the antenna current is proportional to the 
> accu discharge current and also to the voltage (Power supply running 
> in fully duty cycle, i.e. not regulated). As you can see the 
> experiment took 2.5 hours. The accu has a display (second attachment) 
> showing the state of discharge. At the beginning of the experiment, 
> the accu was charged to 98%, at the end it was at 18%. As you see in 
> the graph, the current and voltage dropped by just 1.6 % after a 50% 
> discharge and by 12 % at the end of the transmission. These are 
> outstanding results!
>
> Well, the distributor is German but the accu cells are from China 
> anyway. So why not buying in China directly?
> There is an online distributor which makes offers that are hard to 
> belive!
> For example: 
> https://www.dhgate.com/product/12-v-100ah-lifepo4-battery-for-solar/439384307.html#ctabBox 
> | 1 kWh/50$
> or even:
> https://www.dhgate.com/product/60-v-60ah-lifepo4-60-v-60ah-lifepo4-de-litio/445395613.html#s1-9-1b;searl 
> | 1 kWh/38.3$
>
> How is this possible? Is it just 'fake'? I'm going to risk to buy one. 
> No risk, no fun, as someone recently said.
>
> 73, Stefan


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    Hi Stefan,<br>
    <br>
    As I understand the offer from your last link, they sell "recycled
    bicycle" batteries (?? - with 12 volts - ??) that once had 100 Ah
    when they were, with a remaining capacity of 40 Ah (as shown in one
    of the ads as "item condition") for use as solar power buffer, where
    the degraded performance doesn't matter. But I wouldn't bet on the
    internal cell resistance, i.e. voltage drop under heavy load...<br>
    <br>
    73,<br>
      Wolf .<br>
    <br>
    <div class="moz-cite-prefix">On 18.03.2019 17:20, DK7FC wrote:<br>
    </div>
    <blockquote type="cite" cite="mid:5C8FC539.1080300@posteo.de">
      <meta http-equiv="content-type" content="text/html;
        charset=ISO-8859-15">
      <div class="moz-text-flowed" style="font-family: -moz-fixed;
        font-size: 13px;" lang="x-western">VLF,
        <br>
        <br>
        After a few months of using my 12V/120Ah LiFePo4 accu (<a
          class="moz-txt-link-freetext"
          href="https://www.robur-akku.de/p/lifepo4-akku-12-volt-120-ah"
          moz-do-not-send="true">https://www.robur-akku.de/p/lifepo4-akku-12-volt-120-ah</a>)
        i am really happy with the performance!
        <br>
        <br>
        During an experiment at the ground loop i'm tracking the antenna
        current, see an example in the attachment. Since the feed point
        resistance is constant, the antenna current is proportional to
        the accu
        discharge current and also to the voltage (Power supply running
        in
        fully duty cycle, i.e. not regulated). As you can see the
        experiment
        took 2.5 hours. The accu has a display (second attachment)
        showing the
        state of discharge. At the beginning of the experiment, the accu
        was
        charged to 98%, at the end it was at 18%. As you see in the
        graph, the
        current and voltage dropped by just 1.6 % after a 50% discharge
        and by
        12 % at the end of the transmission. These are outstanding
        results!
        <br>
        <br>
        Well, the distributor is German but the accu cells are from
        China
        anyway. So why not buying in China directly?
        <br>
        There is an online distributor which makes offers that are hard
        to
        belive!
        <br>
        For example: <a class="moz-txt-link-freetext"
href="https://www.dhgate.com/product/12-v-100ah-lifepo4-battery-for-solar/439384307.html#ctabBox"
          moz-do-not-send="true">https://www.dhgate.com/product/12-v-100ah-lifepo4-battery-for-solar/439384307.html#ctabBox</a> 
        | 1 kWh/50$
        <br>
        or even:
        <br>
        <a class="moz-txt-link-freetext"
href="https://www.dhgate.com/product/60-v-60ah-lifepo4-60-v-60ah-lifepo4-de-litio/445395613.html#s1-9-1b;searl"
          moz-do-not-send="true">https://www.dhgate.com/product/60-v-60ah-lifepo4-60-v-60ah-lifepo4-de-litio/445395613.html#s1-9-1b;searl</a> 
        | 1 kWh/38.3$
        <br>
        <br>
        How is this possible? Is it just 'fake'? I'm going to risk to
        buy one.
        No risk, no fun, as someone recently said.
        <br>
        <br>
        73, Stefan
        <br>
      </div>
    </blockquote>
    <br>
  </body>
</html>

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