Re: [RE-wrenches] AGM battery charging, more details

[Allan Sindelar]

Hugh, This is good advice from an installer who installs lots of small and 12V systems for mobile applications such as RVs. (Please correct us if I'm wrong, Larry.) I'll add two small pieces to Larry's good advice: - Blue Sky Energy also makes a 3024iX, which I believe is a 24V version of the good unit Larry recommends. - The larger units have had reliability issues for us - the Solar Boost SB50 and especially the Solar Boost SB3048. They were the first good MPPT controllers on the market, starting around 1999. We replaced many C40s with these, beginning about a decade ago. But too many have failed years later, and we stopped installing them several years ago. It's been a real disappointment, too, because Blue Sky is one of those great, responsive companies that we want to support, as they have provided good support to us when we've needed it. The iX/IPN Pro set may be completely free of the reliability issues we have experienced. Allan Allan Sindelar al...@positiveenergysolar.com NABCEP Certified Photovoltaic Installer NABCEP Certified Technical Sales Professional New Mexico EE98J Journeyman Electrician Positive Energy, Inc. 3201 Calle Marie Santa Fe, New Mexico 87507 505 424-1112 www.positiveenergysolar.com On 4/26/2011 11:49 AM, Starlight Solar, Larry Crutcher wrote: Hugh,   The Blue Sky Energy 2512iX, IPN Pro, temp sens. and shunt is about $420 online. This combination provides the very best in fully programmable battery charge control for systems under 40 amps. There is no equal for the IPN Pro battery monitoring that I can find. I have tried them all and put the BSE in the top of the class. We have sold over 1000 Blue Sky controllers and will continue selling until something better is available.   If you are looking for a lower cost solution, make sure you use a 3 stage controller with temp compensation. We sell the Samlex America SCC-30AB (about $200) as a low cost 3-stage charge alternative to the Blue Sky product.   Will your diversion load control charge in multiple stages? Holding high voltage on an VRLA battery will shorten the life or may cause thermal runaway. You must, according to every manufacturer, reduce the voltage once the battery is full. "Who actually follows these guidelines?" I hope everyone as the customer is paying you to do it right. Sure, an AGM can survive alternative charge methods but after recycling more than 70 tons of batteries at our little store, I am a believer in proper battery charging and maintenance.   Larry ----- Original Message ----- From: Hugh To: RE-wrenches Sent: Monday, April 25, 2011 11:06 PM Subject: Re: [RE-wrenches] AGM battery charging, more details .........My questions to the Wrenches List is: "What hardware do wrenches use to regulate the charge on an AGM battery?"  Does everyone use this Blue Sky Energy device?  Is it possible to use AGM batteries with a conventional diversion controller such as the Morningstar Tristar, and if so how do you determine the transition from 2.45 V/cell to 2.3 V/cell?  Morningstar offer a timed transition, but without knowledge of current or of SOC this is rather less precise. Both of the charging methods in the agm-faqs linked below (and in the Fullriver document) require measurement of the charging current to determine the correct transition from one stage to the next.  Measurement of dV/dt is also suggested in the case of constant current charging.  Who actually follows these guidelines, and can AGM batteries operate successfully without? thanks! Hugh _______________________________________________ List sponsored by Home Power magazine List Address: RE-wrenches@lists.re-wrenches.org Options & settings: http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org List-Archive: http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org List rules & etiquette: www.re-wrenches.org/etiquette.htm Check out participant bios: www.members.re-wrenches.org

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