<html><head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
</head><body text="#000000" bgcolor="#FFFFFF">Yes good thought Chris -I
doubt if there is an IR tester anywhere on the island - but when I go I
will for sure look at that - thanks for that.<br>
<br>
How would one measure battery resistance with voltage present? I guess
with a known voltage applied and current held constant one could
calculate? but then how do you know you are measuring resistance vs
storing energy? I don't think that's possible - others?<br>
<br>
jc<br>
<span>
</span><br>
<blockquote type="cite"
cite="mid:B8.BB.08058.3D35FE06@smtp34.gate.iad3a.rsapps.net"
style="border: 0px none ! important;">
<div xmlns="http://www.w3.org/1999/xhtml" class="__pbConvHr"
style="margin:30px 25px 10px 25px;"><div
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style="display:inline-block;white-space:nowrap;vertical-align:middle;width:49%;">
<a style="color:#485664
!important;padding-right:6px;font-weight:500;text-decoration:none
!important;" href="mailto:chris@solarwindworks.com"
moz-do-not-send="true">Chris Worcester</a></div> <div
style="display:inline-block;white-space:nowrap;vertical-align:middle;width:48%;text-align:
right;"> <font color="#909AA4"><span style="padding-left:6px">July
14, 2021 at 2:14 PM</span></font></div> </div></div>
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__pbrmquotes="true"
style="color:#909AA4;margin-left:24px;margin-right:24px;"><meta
http-equiv="Content-Type" content="text/html; charset=utf-8"><div
dir="auto">Has an infra-red thermometer been used on every battery's
terminals to check for resistance? I recall, although this might be my
own thoughts, that internal resistance of each cell can be measured with
an ohm meter...</div><div dir="auto"><br></div><div dir="auto"><br></div><div
dir="auto"><br></div><div id="composer_signature" dir="auto"><meta
http-equiv="Content-Type" content="text/html; charset=utf-8"><div
style="font-size:85%;color:#575757" dir="auto">Chris Worcester </div><div
style="font-size:85%;color:#575757" dir="auto"><a class="moz-txt-link-abbreviated" href="mailto:chris@solarwindworks.com">chris@solarwindworks.com</a></div><div
style="font-size:85%;color:#575757" dir="auto">530-448-9692</div><div
style="font-size:85%;color:#575757" dir="auto"><br></div><div
style="font-size:85%;color:#575757" dir="auto">Sent from my Samsung
Galaxy s9.</div></div><div dir="auto"><br></div><div><br></div><div
dir="auto" style="font-size:100%;color:#000000" align="left"><div>--------
Original message --------</div><div>From: Jeff Clearwater
<a class="moz-txt-link-rfc2396E" href="mailto:jeffc@villagepowerdesign.com"><jeffc@villagepowerdesign.com></a> </div><div>Date: 7/14/21 1:42 PM
(GMT-08:00) </div><div>To: RE-wrenches
<a class="moz-txt-link-rfc2396E" href="mailto:re-wrenches@lists.re-wrenches.org"><re-wrenches@lists.re-wrenches.org></a> </div><div>Subject: Re:
[RE-wrenches] How Best to Load Test 2 V Cells </div><div><br></div></div>Hey
Jay,<br>
<br>
Yes the Sunny island Master of this Quad SI AC-coupled off-grid system
has been giving automatic Eq and Full charge charges perodically as
appropriate to this 48 V EnergyCell RE2700 pack.<br>
<br>
We are getting whole pack volt drops way before we should at 600 well-
maintained cycles. When we do whole pack testing - when the voltage
drops off there are 5 of the 24 cells lagging - their voltage drops
faster than the rest - but they operate well between 50%-100% - all
busbars have been triple checked for corrosion and tourque. <br>
<br>
So it looks like they just aged prematurely - so I'm in the process of
collating data from EnnexOS to get exact numbers on how they've been
treated. But even with a few hard cycles they should held up better
than they have. So perhaps a warranty claim - I've gone through charge
settings with SMA etc. I did have the AHrs programmed slightly below
rated AHrs due to confusion of whether the SI uses the 20 hr or 10 hr
rate (in Europe they use 10 but apparently - unbeknowst to me - the US
SI uses the 20 Hr - I swear SMA tech support years ago told me 10
hours) but now they are claiming that might be the culprit - I have a
hard time believing that setting the Ahour rating in the SI to 2100
instead of 2288 as rated would lead to pack failure - but they are
claiming that could have contributed.<br>
<br>
Thoughts?<br>
<br>
Best,<br>
<br>
Jeff<br>
<br>
<br>
<span>
</span><br>
<br>
</div>
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style="margin:30px 25px 10px 25px;"><div
style="width:100%;border-top:2px solid #EDF1F4;padding-top:10px;"> <div
style="display:inline-block;white-space:nowrap;vertical-align:middle;width:49%;">
<a style="color:#485664
!important;padding-right:6px;font-weight:500;text-decoration:none
!important;" href="mailto:jeffc@villagepowerdesign.com"
moz-do-not-send="true">Jeff Clearwater</a></div> <div
style="display:inline-block;white-space:nowrap;vertical-align:middle;width:48%;text-align:
right;"> <font color="#909AA4"><span style="padding-left:6px">July
14, 2021 at 1:42 PM</span></font></div> </div></div>
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__pbrmquotes="true"
style="color:#909AA4;margin-left:24px;margin-right:24px;">
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
Hey Jay,<br>
<br>
Yes the Sunny island Master of this Quad SI AC-coupled off-grid system
has been giving automatic Eq and Full charge charges perodically as
appropriate to this 48 V EnergyCell RE2700 pack.<br>
<br>
We are getting whole pack volt drops way before we should at 600 well-
maintained cycles. When we do whole pack testing - when the voltage
drops off there are 5 of the 24 cells lagging - their voltage drops
faster than the rest - but they operate well between 50%-100% - all
busbars have been triple checked for corrosion and tourque. <br>
<br>
So it looks like they just aged prematurely - so I'm in the process of
collating data from EnnexOS to get exact numbers on how they've been
treated. But even with a few hard cycles they should held up better
than they have. So perhaps a warranty claim - I've gone through charge
settings with SMA etc. I did have the AHrs programmed slightly below
rated AHrs due to confusion of whether the SI uses the 20 hr or 10 hr
rate (in Europe they use 10 but apparently - unbeknowst to me - the US
SI uses the 20 Hr - I swear SMA tech support years ago told me 10
hours) but now they are claiming that might be the culprit - I have a
hard time believing that setting the Ahour rating in the SI to 2100
instead of 2288 as rated would lead to pack failure - but they are
claiming that could have contributed.<br>
<br>
Thoughts?<br>
<br>
Best,<br>
<br>
Jeff<br>
<br>
<br>
<span>
</span><br>
<br>
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