I do have a Megatron battery tester that does test internal resistance whit voltage present. The battery Manu usually has that information. When I get my Unigy II battery banks they supply the sheet w/ those #. Did you say what the battery charge settings were? Not much use at this point as it is tough to clean up AGM cells. > On Jul 14, 2021, at 5:43 PM, Jeff Clearwater <[email protected] > <mailto:[email protected]>> wrote: > > 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. > > 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? > > jc > >> Chris Worcester <mailto:[email protected]> July 14, 2021 at 2:14 PM >> 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... >> >> >> >> Chris Worcester >> [email protected] <mailto:[email protected]> >> 530-448-9692 >> >> Sent from my Samsung Galaxy s9. >> >> >> -------- Original message -------- >> From: Jeff Clearwater <[email protected]> >> <mailto:[email protected]> >> Date: 7/14/21 1:42 PM (GMT-08:00) >> To: RE-wrenches <[email protected]> >> <mailto:[email protected]> >> Subject: Re: [RE-wrenches] How Best to Load Test 2 V Cells >> >> Hey Jay, >> >> 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. >> >> 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. >> >> 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. >> >> Thoughts? >> >> Best, >> >> Jeff >> >> >> >> >> Jeff Clearwater <mailto:[email protected]> July 14, 2021 at 1:42 >> PM >> Hey Jay, >> >> 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. >> >> 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. >> >> 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. >> >> Thoughts? >> >> Best, >> >> Jeff >> >> >> >> >> >> >> _______________________________________________ >> List sponsored by Redwood Alliance >> >> Pay optional member dues here: http://re-wrenches.org >> <http://re-wrenches.org/> >> >> List Address: [email protected] >> <mailto:[email protected]> >> >> Change listserver email address & settings: >> http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org >> <http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org> >> >> There are two list archives for searching. When one doesn't work, try the >> other: >> https://www.mail-archive.com/[email protected]/ >> <https://www.mail-archive.com/[email protected]/> >> http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org >> <http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org> >> >> List rules & etiquette: >> http://www.re-wrenches.org/etiquette.htm >> <http://www.re-wrenches.org/etiquette.htm> >> >> Check out or update participant bios: >> http://www.members.re-wrenches.org <http://www.members.re-wrenches.org/> >> > > _______________________________________________ > List sponsored by Redwood Alliance > > Pay optional member dues here: http://re-wrenches.org > <http://re-wrenches.org/> > > List Address: [email protected] > <mailto:[email protected]> > > Change listserver email address & settings: > http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org > <http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org> > > There are two list archives for searching. 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> Tump > <blocked::mailto:[email protected]%22%20%5Co%20%22blocked::mailto:[email protected]>[email protected] > www.SWNL.net > <blocked::http://www.swnl.net/%22%20%5Co%20%22blocked::http://www.swnl.net/> > Solarwinds Northernlights > Serving Mid Coast Maine & Northern California > 207-832-7574 Cl. 610-517-8401 > > Blair "TUMP" May > ******** MAINE'S CHARTER ******** > NABCEP "Certified PV Installer" > > ******** MAINE'S CHARTER ******** > Trace Xantrex "Certified" Dealer / Installer" >
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