Hi William,
I think you are smart to taking your time going to Lithium Ion. I will let others work the math as each application/client is really different. I have a few clients offgrid who are early adopters and there have been a few failures I have observed. For grid based Apps I really do not concern myself because the grid is there for back-up. I will just say the LFP battery management system is a new set of ways to lose power offgrid. I am backing up my clients and have always done that at my offgrid home. Here is a link to the testing I have been watching since I started testing advanced battery technology in the field for Schneider in 2016. A 61% failure rate is not good news to me. Blue Ion And Discover is not in the testing and the Muarta battery they use is doing very well. https://www.solarquotes.com.au/blog/6th-canberra-battery-test/ [1] Dave Angelini Offgrid Solar "we go where powerlines don't" http://members.sti.net/offgridsolar/ [2] e-mail offgridso...@sti.net [3] text 209 813 0060 On Tue, 23 Jul 2019 15:08:49 -0700, William Miller wrote: Friends: I am a complete newbie to any lithium technologies, so please forgive some newbie questions: I am used to working in amp hours. If we are looking for a battery bank in the range of 100 kWh, this converts to about 2,083 amp/hours at 48 VDC. Is my arithmetic correct? An on-line calculator seems to confirm this. The biggest Blue Ion 2 battery is 16 kwh. At 48 VDC this is about 333 amp/hours. This is like an L16. To get 100 kwh you would need to parallel 6 strings of the 16 kWh batteries. I would never do this with L-16s. Is anyone worried about circulating currents in this type of installation? Is there technology to prevent one string from cannibalizing another? Here is another, more academic question below: In case I am using a term I made up (which is often the case), I define circulating currents as currents flowing between parallel strings without any outside influence. For example, if you disconnected all charging and loads from an array with two parallel strings, unless the strings were absolutely identical in electrical characteristics, there would be some current flowing between the two strings. In my opinion this is the Achilles heel in parallel strings. Also my opinions: 2. The more strings you have the more chance there will be debilitating circulating currents. 3. The older the batteries, the more the electrical characteristics will vary and the more likely you will get higher circulating currents. It is my theory that if you can measure the circulating currents, or the difference between parallel battery strings at any point in the operation of same, you can get a read on the health of the strings. The more the operating or idle currents diverge, the more one string will discharge the other string. I guess this is some part of a battery management system. I am guessing for the Blue Ion 2 to work in 6 parallel strings, they need to monitor and control this difference in currents. We just installed a flooded battery array (2 strings of 4 Deka M6100-33 batteries). My plan is to retrofit the installation with a 1000A/100mv shunt in the negative leads of both strings. With a DVM I can spot check the circulating currents to learn about the battery health. In fact I have a remote monitoring system [4] with some spare ports that can log these values. Might be an interesting experiment. I appreciate any input on the viability of the Blue Ion 2 or other small battery systems in multi-string installations. My customers are asking for new technology, but I instinctively avoid parallel battery strings. William Miller Miller Solar 17395 Oak Road, Atascadero, CA 93422 805-438-5600 www.millersolar.com [5] CA Lic. 773985 Quote of the month: "As they age, batteries transition from energy storage devices to energy consuming devices." W. Miller FROM: RE-wrenches [mailto:re-wrenches-boun...@lists.re-wrenches.org [6]] ON BEHALF OF Lou Russo SENT: Saturday, July 20, 2019 1:50 PM TO: RE-wrenches SUBJECT: Re: [RE-wrenches] Large Off-Grid Residential System Blue Ion 2.0 with Outback or SMA. Works every time. Blue Planet's tech support is great, the warranty is even better. Aloha, Lou Russo l...@spreesolarsystems.com [7] 808 345 6762 Spree Solar Systems LLC CT-34322 On Sat, Jul 20, 2019 at 10:36 AM Jay wrote: Hi Marco, Is the max surge 7kw, which is what is listed on line? Jay Peltz Power On Jul 19, 2019, at 3:10 PM, Marco Mangelsdorf wrote: Seven to eight Tesla Powerwalls will get you that assuming that the service entrance is no bigger than 200A. marco On Friday, July 19, 2019, Jason Szumlanski wrote: What are current popular options for battery based systems in the 100kWh range? Preferably Lithium. Also, what inverter pairing is suggested with total stacked capacity of 36kW, 120/240V? This is slightly larger than some of the systems I have worked with recently. I'm a bit out of the loop, particularly on the battery side of things. Jason Szumlanski Florida Solar Design Group _______________________________________________ List sponsored by Redwood Alliance List Address: RE-wrenches@lists.re-wrenches.org [11] Change listserver email address & settings: http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org [12] List-Archive: http://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/maillist.html [13] List rules & etiquette: www.re-wrenches.org/etiquette.htm [14] Check out or update participant bios: www.members.re-wrenches.org [15] _______________________________________________ List sponsored by Redwood Alliance List Address: RE-wrenches@lists.re-wrenches.org [16] Change listserver email address & settings: http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org [17] List-Archive: http://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/maillist.html [18] List rules & etiquette: www.re-wrenches.org/etiquette.htm [19] Check out or update participant bios: www.members.re-wrenches.org [20] -- Links: ------ [1] https://www.solarquotes.com.au/blog/6th-canberra-battery-test/ [2] http://members.sti.net/offgridsolar/ [3] mailto:offgridso...@sti.net [4] https://millersolar.com/MillerSolar/Portfolio/Commercial/Cal_Trans/Remote/Remote_Control.html [5] http://www.millersolar.com/ [6] mailto:re-wrenches-boun...@lists.re-wrenches.org [7] mailto:l...@spreesolarsystems.com [8] mailto:jay.pe...@gmail.com [9] mailto:ma...@pvthawaii.com [10] mailto:ja...@floridasolardesigngroup.com [11] mailto:RE-wrenches@lists.re-wrenches.org [12] http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org [13] http://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/maillist.html [14] http://www.re-wrenches.org/etiquette.htm [15] http://www.members.re-wrenches.org [16] mailto:RE-wrenches@lists.re-wrenches.org [17] http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org [18] http://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/maillist.html [19] http://www.re-wrenches.org/etiquette.htm [20] http://www.members.re-wrenches.org
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