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The battery cables being close together, twisted too if possible,
help reduce cable inductance<br>
which can cause voltage drop across those cables at higher currents
with 120 Hz ripple.<br>
Mainly with low frequency transformer inverter/chargers. <br>
<br>
It's better to have them closer together than far apart, especially
for longer battery cables.<br>
<br>
🌜boB🌛<br>
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<div class="moz-cite-prefix">On 6/29/2023 9:24 AM, Starlight via
RE-wrenches wrote:<br>
</div>
<blockquote type="cite"
cite="mid:94A30F84-A675-42E7-A973-A73A6F90753B@starlightsolar.com">
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
You may already know but… Are your DC cables bonded together and
twisted where possible to reduce magnetic fields? Higher the
current and greater the loop area, the stronger the fields are.
More parallel loops, the greater the combined flux = loud Hums.
<div class="">
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auto; -webkit-text-stroke-width: 0px; text-decoration: none;">Larry
Crutcher</div>
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class=""><br class="">
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<br class="Apple-interchange-newline">
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<div><br class="">
<div class="">On Jun 29, 2023, at 8:19 AM, Kirk Herander via
RE-wrenches <<a
href="mailto:re-wrenches@lists.re-wrenches.org"
class="moz-txt-link-freetext" moz-do-not-send="true">re-wrenches@lists.re-wrenches.org</a>>
wrote:</div>
<br class="Apple-interchange-newline">
<div class="">All,
<div dir="auto" class=""><br class="">
</div>
<div dir="auto" class="">I am in the middle of commissioning a
480kwh BP LFP battery bank, connected to -10- OB Radian 8kw
inverter/chargers.</div>
<div dir="auto" class=""><br class="">
</div>
<div dir="auto" class="">For the DC combiner I am using
midnite 2000 amp combiner boxes, modified to mount class T
fuses on the positive bus, for both battery inputs and
inverter outputs.</div>
<div dir="auto" class=""><br class="">
</div>
<div dir="auto" class="">For starters, I set the master
inverter at a max charge rate of 20 AC amps, which equates
to a DC charge of about 74 A. All the other inverters are
automatically set to this charge rate as well.</div>
<div dir="auto" class=""><br class="">
</div>
<div dir="auto" class="">Turning the chargers on one by one, I
started to get quite an audible vibration from the combiner
box at a combined charge of about 400 to 500 A. </div>
<div dir="auto" class=""><br class="">
</div>
<div dir="auto" class="">So I took the cover off of the
combiner, which was vibrating noticabllly by feel. Most of
the noise was from the cover not fitting tight. But the The
box itself is also vibrating by feel.</div>
<div dir="auto" class=""><br class="">
</div>
<div dir="auto" class="">I took the combined charge up to 640A
dc. This level of vibration definitely increases with an
increased charge rate. And I am surprised because after all,
we’re not talking AC here we’re talking DC. It almost
reminds me of a large AC transformer in its behavior. The
vibration did not seem to be originating at the inverters,
then resonating to the combiner.</div>
<div dir="auto" class=""><br class="">
</div>
<div dir="auto" class="">I can dampen the vibration by adding
a few things, but I’m surprised that this is happening. All
connections in the combiner are tightened properly. Ideas?</div>
<div dir="auto" class=""><br class="">
</div>
<div dir="auto" class=""><br class="">
</div>
<div dir="auto" class=""><br class="">
</div>
<div dir="auto" class=""><br class="">
</div>
<div dir="auto" class=""><br class="">
</div>
<div dir="auto" class=""><br class="">
</div>
<div dir="auto" class=""><br class="">
</div>
<div dir="auto" class=""><br class="">
</div>
<div dir="auto" class=""><br class="">
</div>
<div dir="auto" class=""><br class="">
</div>
<span class="gmail_signature_prefix">-- </span><br class="">
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<div style="font-family: Arial; font-size: 16px; margin:
0in 0in 0.0001pt;" class=""><span style="font-size:10pt"
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class="" moz-do-not-send="true"><b class="">Kirk
Herander / </b></a><b class=""><a
href="mailto:kirkh@vermont.solar" title="Send an
email to kirkh@vermont.solar; Send an email to
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