Temperature compensated battery voltages are only be used for charging regulation settings. The charging setpoints need to be reduced when the batteries are warm because they are more easily caused to gas (produce hydrogen) at lower voltage levels as the electrolyte temperatures increase. The opposite occurs with colder temperatures - the gassing voltage point rises as the electrolyte gets cold. Generator start setpoints should use actual battery voltages and not the temperature compensated voltage as the discharge setpoints do not have any relationship with the gassing voltage. If anything, the generator start and LBCO settings would need to be reverse compensated - reduced when the battey gets colder instead of increased when the battery gets colder as with the charging setpoints. This could result in excessive levels of discharge however if not done correctly - and I have never seen any battery manufacturers provide a discharge temperature coefficient to use... Christopher
------------------------------------ Christopher Freitas Director of Research and Development OutBack Power Systems, Inc. [EMAIL PROTECTED] Tel 360 435 6030 cell 360 202 4239 ________________________________ From: [EMAIL PROTECTED] on behalf of Phil Schneider Sent: Tue 8/19/2008 7:43 PM To: re-wrenches@lists.re-wrenches.org Subject: Re: [RE-wrenches] offgrid system question Max, I agree with the previous comments regarding likely issues to pursue with this system. Mr. Undercuffler mentioned temperature compensation as a piece to the puzzle. I was recently troubleshooting a system where there was a large difference between actual and compensated voltages with a SW Plus. The SW Plus uses actual voltage to make decisions regarding generator starting (Xantrex tech support didn¹t have a known reason for this), which led to premature generator starting (and LBCO shutoff) when the batteries were warm. It may be worth checking on which voltage (compensated or not) the XW uses to make these types of decisions. P. Phil Schneider Creative Energies --- On Mon, 8/18/08, Max Balchowsky <[EMAIL PROTECTED]> wrote: > From: Max Balchowsky <[EMAIL PROTECTED]> > Subject: Re: [RE-wrenches] offgrid system question > To: "RE-wrenches" <re-wrenches@lists.re-wrenches.org> > Date: Monday, August 18, 2008, 3:00 PM > Dear wrenches, going to look at a system installed by others > and would like some input from some of you with more off > grid experience than I have ( 4 systems over the years). the > system was put on a new home - off grid 20 sharp ND123UJF > panels 4 modules in series - 5 parrallel strings, 2460 total > array dc voltage. mppt 60-150 charge controller, 12 sun > extender sealed AGM batteries, 305 AH at 12 vdc, wired for > 915 AH at 48 volt DC. The system is tripping off when the AC > unit trys to start - AC is comfortmaker 3.5 ton 13 seer. > They say start up inrush is 104 amps (sounds high to me) and > they put a DST 10 soft start on the unit (I think that's > just a big capacitor). I haven't been on site yet but it > sounds to me that they just didn't design enough > inverter capacity into the system...... What are your > thoughts? > > Max Balchowsky > SEE Systems > > _______________________________________________ > List sponsored by Home Power magazine > > RE-wrenches@lists.re-wrenches.org > > http://lists.re-wrenches.org/listinfo.cgi/re-wrenches-re-wrenches.org > > List rules & etiquette: > http://www.re-wrenches.org/etiquette.htm > > Check out participant bios: > www.members.re-wrenches.org _______________________________________________ List sponsored by Home Power magazine RE-wrenches@lists.re-wrenches.org http://lists.re-wrenches.org/listinfo.cgi/re-wrenches-re-wrenches.org List rules & etiquette: http://www.re-wrenches.org/etiquette.htm Check out participant bios: www.members.re-wrenches.org _______________________________________________ List sponsored by Home Power magazine RE-wrenches@lists.re-wrenches.org http://lists.re-wrenches.org/listinfo.cgi/re-wrenches-re-wrenches.org List rules & etiquette: http://www.re-wrenches.org/etiquette.htm Check out participant bios: www.members.re-wrenches.org EMAIL CONFIDENTIALITY NOTICE: The preceding message (including attachments) is covered by the Electronic Communication Privacy Act, 18 U.S.C. sections 2510-2521, is confidential, and may also be protected by attorney-client or other privilege. If you believe that it has been sent to you in error, please do not read it. If you are not the intended recipient,you are hereby notified that any retention, dissemination, distribution, or copying of this communication is strictly prohibited. Please reply to the sender that you have received the message in error, then delete it. Thank you.
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