Return-Path: Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by klubnl.pl (8.14.4/8.14.4/Debian-8+deb8u2) with ESMTP id x2J9m3MX032242 for ; Tue, 19 Mar 2019 10:48:11 +0100 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1h6B7N-0004FW-Nk for rs_out_1@blacksheep.org; Tue, 19 Mar 2019 09:33:10 +0000 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1h6B4R-0004EZ-3S for rsgb_lf_group@blacksheep.org; Tue, 19 Mar 2019 09:30:07 +0000 Received: from mout02.posteo.de ([185.67.36.66]) by relay1.thorcom.net with esmtps (TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384:256) (Exim 4.91) (envelope-from ) id 1h6B4H-00040c-50 for rsgb_lf_group@blacksheep.org; Tue, 19 Mar 2019 09:29:57 +0000 Received: from submission (posteo.de [89.146.220.130]) by mout02.posteo.de (Postfix) with ESMTPS id 50AD12400FD for ; Tue, 19 Mar 2019 10:29:53 +0100 (CET) X-DKIM-Result: Domain=posteo.de Result=Signature OK DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=posteo.de; s=2017; t=1552987794; bh=uEOX9wjdzr8iNRGi3T/Fa5QgMGuBA/FK9LkILqigrLI=; h=Date:From:To:Subject:From; b=h5I4NjFNzfyg8LiLAkgpat3xEhrlLX9FpEfNk4k2bw9j2SgIGgBurPzSBQZJnyqbU uBwIqsPYWbL44qGELDZW5PrWYwBOyCBKTQzqZJrwjezUHcXwt7MzHvBjHWAf8QT5uW CaLw0i/B77ffg7lafAmBMcw2u8go80A9Sw28VRBJ8v2SxQb3Jw+mMZTz4chMFxVsyO PEPEQbGjIby5A55CUWPN215YdWhpoQXToFJycTB4qt/4V4cIE98mxfjdV7jXLZkdmF aleS/Dww4nz8a/wR83c8nVV/F+gHIAloTkPIUOhVO6/tSoTnJ2LXAm5E16xGHJU0Zk N2whdyTBix9Xg== Received: from customer (localhost [127.0.0.1]) by submission (posteo.de) with ESMTPSA id 44Nnnr46NBz9rxN for ; Tue, 19 Mar 2019 10:29:52 +0100 (CET) Message-ID: <5C90B68E.2090203@posteo.de> Date: Tue, 19 Mar 2019 10:29:50 +0100 From: DK7FC User-Agent: Mozilla/5.0 (Windows; U; Windows NT 6.1; de; rv:1.9.1.8) Gecko/20100227 Thunderbird/3.0.3 MIME-Version: 1.0 To: rsgb_lf_group@blacksheep.org References: <5C8FC539.1080300@posteo.de> <2b920d6f-fed5-c3af-9574-703289c8259f@freenet.de> In-Reply-To: <2b920d6f-fed5-c3af-9574-703289c8259f@freenet.de> X-Spam-Score: -2.3 (--) X-Spam-Report: Spam detection software, running on the system "relay1.thorcom.net", has NOT identified this incoming email as spam. The original message has been attached to this so you can view it or label similar future email. If you have any questions, see the administrator of that system for details. Content preview: Hello Wolfgang, Hmm, where do you find the quote "recycled bicycle" on that site? As far as know, bicycle batteries ore usually Li-ion, not LiFePo4. They write "Vida útil: más de 2000 ciclos". This is not very precis [...] Content analysis details: (-2.3 points, 5.0 required) pts rule name description ---- ---------------------- -------------------------------------------------- -2.3 RCVD_IN_DNSWL_MED RBL: Sender listed at http://www.dnswl.org/, medium trust [185.67.36.66 listed in list.dnswl.org] -0.0 SPF_PASS SPF: sender matches SPF record 0.0 HTML_MESSAGE BODY: HTML included in message X-Scan-Signature: e5f33499c82e559d1cf2f25253946608 Subject: Re: LF/VLF: QRO in portable experiments by using LiFePo4 accus from China? Content-Type: multipart/alternative; boundary="------------000203090009060508020807" X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: * X-Spam-Status: No, hits=1.1 required=5.0 tests=HTML_20_30,HTML_MESSAGE, RISK_FREE autolearn=no version=2.63 X-SA-Exim-Scanned: Yes Sender: owner-rsgb_lf_group@blacksheep.org Precedence: bulk Reply-To: rsgb_lf_group@blacksheep.org X-Listname: rsgb_lf_group X-SA-Exim-Rcpt-To: rs_out_1@blacksheep.org X-SA-Exim-Scanned: No; SAEximRunCond expanded to false This is a multi-part message in MIME format. --------------000203090009060508020807 Content-Type: text/plain; charset=ISO-8859-15; format=flowed Content-Transfer-Encoding: 8bit Hello Wolfgang, Hmm, where do you find the quote "recycled bicycle" on that site? As far as know, bicycle batteries ore usually Li-ion, not LiFePo4. They write "Vida útil: más de 2000 ciclos". This is not very precise. Usually it means that the battery has a remaining capacity of 85% after 2000 cycles of 80% DoD. If the remaining capacity would actually be 40 Ah only, the cells would be extremely old. I would rather expect that "> 40 Ah" means just a search category. Am i naive? :-) Anyway, the offer is so cheap, i'm going to order one and test it in a VLF experiment, then we know! And if it has 100 Ah actually, then i'll buy 3 of these 60V/60Ah versions ;-) 73, Stefan Am 19.03.2019 08:54, schrieb Wolfgang Büscher: > 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 > --------------000203090009060508020807 Content-Type: text/html; charset=ISO-8859-15 Content-Transfer-Encoding: 8bit Hello Wolfgang,

Hmm, where do you find the quote "recycled bicycle" on that site? As far as know, bicycle batteries ore usually Li-ion, not LiFePo4.
They write "Vida útil: más de 2000 ciclos". This is not very precise. Usually it means that the battery has a remaining capacity of 85% after 2000 cycles of 80% DoD. If the remaining capacity would actually be 40 Ah only, the cells would be extremely old. I would rather expect that "> 40 Ah" means just a search category.
Am i naive? :-)
Anyway, the offer is so cheap, i'm going to order one and test it in a VLF experiment, then we know! And if it has 100 Ah actually, then i'll buy 3 of these 60V/60Ah versions ;-)

73, Stefan


Am 19.03.2019 08:54, schrieb Wolfgang Büscher:
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

--------------000203090009060508020807--