Jeff, This has to do with testing... it takes a lot of time to do real cycle life testing even if you are doing accelerated testing.
Some of the Lithium manufacturers that claim 8000 -10,000+ cycles at 80-100% DOD I think are not being .... well you know... I personally think they are oversizing the cells to ensure that a 100% DOD cycle is just 60-80% DOD... Just to give you an idea, we incorporated some changes into our batteries last year that we had been working on since 2015. By adding carbon to the S4500 and S5000 batteries by June of 2019 we had simulated over 4000 cycles on the Series 5000's. By the time we released the product we had already done 4 years of testing to verify operation with multiple testing partners. We are still testing those batteries today to determine their true failure point and cycle lives... The hard part is what is a cycle, and controlling the depth of discharge for every single cycle. With LFP you have an onboard computer that keeps track of all the power in and out, what discover is doing is a smart thing to do, they are keeping track of the total power in and out and using that for warranty. Battery warranties are much like panel warranties, especially with Lithium... You will lose some capacity right out of the gate, but the warranty is usually 70-80% of capacity for "X" amount of cycles or thruput power. I kind of like the way Discover is doing their warranties, as to how do you prove that someone has over cycled their battery bank? <http://www.rollsbattery.com> <http://www.rollsbattery.com> <http://www.rollsbattery.com> <http://www.rollsbattery.com> <http://www.rollsbattery.com> <http://www.rollsbattery.com> <http://www.rollsbattery.com> <http://www.rollsbattery.com> <http://www.rollsbattery.com> <http://www.rollsbattery.com> <http://www.rollsbattery.com> <http://www.rollsbattery.com> <http://www.rollsbattery.com> <http://www.rollsbattery.com> <http://www.rollsbattery.com> <http://www.rollsbattery.com> Steve Higgins ⋅ Technical Services Manager t +1.902.597.4020 m +1.206.790.5840 f +1.902.597.8447 e st...@surrette.com <#SignatureSanitizer_SafeHtmlFilter_> <http://www.facebook.com/RollsBattery> <http://www.facebook.com/RollsBattery> <http://www.twitter.com/RollsBattery> <https://www.youtube.com/user/RollsBattery> <https://www.linkedin.com/company/rolls-battery-engineering> <http://www.instagram.com/RollsBattery> <http://www.instagram.com/RollsBattery> <http://www.instagram.com/RollsBattery> ------------------------------ *Become a Certified PV Professional. 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If you receive this email in error, please contact the sender and delete or destroy this message and all copies. ------------------------------ On Tue, Aug 11, 2020 at 11:30 AM Jeff Clearwater < je...@villagepowerdesign.com> wrote: > Hey All, > > Great Thread - so does anyone have the missing cycle life information for > the Discover AES and Fortress Eflex below? > > > - Discover AES (42-48-6650) (Spec sheet does not list cycles) (but > does give 38MWh warranty > > see analysis sheet here: > https://aeesolar.com/wp-content/uploads/2019/02/DISCOVER-AES-The-AES-LiFePO-Battery-Solar-Off-grid-Advantage-20190124-AEE.pdf > > that sheet says "With a designed DOD of 50% lead-acid batteries are > expected to last ~1500 cycles or 4 Years of daily cycling. With the > Discover AES 10 Year 38 MWh Warranty, you’ll be half way into your 3rd Set > of lead-acid batteries." > > That would imply 5250 cycles under warranty - but surely it has more in it > than that for an expensive LFP! Can't find a reference anywhere. 38 > MWH/6.65 KWH = 5700 cycles - their own spreadsheet says "Cycle Life (@DOD > rating): NA" Impressive warranty but how much past the warranty they > don't seem to want to venture. It's the most expensive of the options > listed here (well comparable to BI) and comes with highest quality > recommendation and has great closed loop communications - but would love to > know the top end cycle figure. > > > - Fortress EVault (18KWH) (Spec sheet says 6000) > - Fortress EFlex (5.4 KWH) ( Spec sheet does not list cycles) > - Simpliphi 3.8 (spec sheet says 10,000+ @ 80%) > - Blue Ion 2.0 spec sheet says 8000 @ 100% DOD > > Does anyone know why Simpliphi and BI an claim such high cycle life > whereas Fortress says 6000 and AES won't venture it? same chemistry? so > is Fortress underselling or the other folks over selling? > Has anyone even seen a curve of cycle life vs. DOD for LFP? or is that > not so much a curve as a flat line? > > thanks! > > Jeff > > ~~~~~~~~~~~ > Jeff Clearwater > VillageLab > Village Power Design > www.villagelab.net > www.villagepowerdesign.com > cell - 413-559-9763 > ~~~~~~~~~~~~~~~~~~~~~~~ > > > > > Richard Scott wrote on 8/11/20 10:35 AM: > > Also keep in mind that the battery charge/discharge efficiency is much > higher for lithium batteries compared to lead acid. > > Richard > > > On Tue, Aug 11, 2020 at 8:17 AM Jay <jay.pe...@gmail.com> wrote: > >> Hi William, >> >> I dont do the math based on up front kwh cost, but on lifetime kWh based >> on the number of cycles per average DOD that are going to be used. I use >> this same formula to compare all batteries to each other. >> >> Jay >> >> Peltz power. >> >> For example, a Rolls L16 ex has 3500 cycles at 50% DOD, and it’s a 371 >> amp hr at 6v or 2.226 kWh >> Retail is $400 >> >> 3500 cycles x 1.1 kWh At 50 DOD=3850 kWh >> $400 / 3850 kWh = $.10 kWh >> 10 years of 50% cycling daily >> >> Compared to say a mid grade US battery, 1400 cycles to 50%, 400 amp hr. >> 2.4 kWh >> $325/1680 kWh = $.19 kWh. >> 3.8 yrs life >> >> Compare to say BI >> $1000 kWh roughly. >> If you get 10,000 cycles, that works out to same cost. $.10 per kWh. >> 27 yrs, but will the chemistry actually last that long? >> However, you have a massive upfront money cost. >> And for those of us off grid, you can’t really cycle 100%. And many >> lithium in the fine print don’t want you to charge to 100% daily. Let’s >> assume you start the generator at 10% and charge to 95%, now your usable >> amount is actually 85%, not 100%. >> Cost per kWh goes to $.12. >> >> >> >> >> On Aug 11, 2020, at 6:04 AM, William Miller <will...@millersolar.com> >> wrote: >> >> >> >> Friends: >> >> >> >> I am hoping y’all can tell me I am doing something wrong with my >> arithmetic. I have registered to purchase Blue Planet batteries and priced >> the product. I come up with math that indicates that comparing usable >> amp/hours to usable amp/hours, that the Blue Planet is 5 times the cost of >> a flooded L-16 battery array on a cost per kilowatt/hour. Can this be true? >> >> >> >> I am using these parameters: >> >> >> >> 1. DOD for flooded L16s: 50% >> >> 2. DOD for Blue Planet: 100% >> >> >> >> I hope I am wrong. >> >> >> >> Also, we often install battery arrays that are upwards of 4,000 AH. For >> example, we installed 5,668 of East Penn flooded batteries on a couple of >> projects. To acquire the same capacity in Blue Planet would require 9 >> cabinets (again 50% DOD versus 100% DOD). Is this correct design? Is it >> practical to install 9 cabinets? Does the system detect and compensate for >> circulating currents in this many parallel strings? >> >> >> >> Thanks in advance. >> >> >> >> William Miller >> >> >> >> >> >> *From:* RE-wrenches [mailto:re-wrenches-boun...@lists.re-wrenches.org] *On >> Behalf Of *Jerry Shafer >> *Sent:* Sunday, August 9, 2020 12:02 PM >> *To:* RE-wrenches >> *Subject:* Re: [RE-wrenches] Best Battery >> >> >> >> Wrenchel have been very happy with all my Blue Planet battery systems, >> best battery you will install. >> >> Jerry >> >> >> >> On Sun, Aug 9, 2020, 11:19 AM <drake.chamber...@redwoodalliance.org> >> wrote: >> >> Hello Wrenches, >> >> What is the best Li-Ion battery to use with an off grid system? >> >> Thanks, >> >> Drake >> Athens Electric >> >> -- >> _______________________________________________ >> List sponsored by Redwood Alliance >> >> List Address: RE-wrenches@lists.re-wrenches.org >> >> Change listserver email address & 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 or update participant bios: >> www.members.re-wrenches.org >> >> _______________________________________________ >> List sponsored by Redwood Alliance >> >> List Address: RE-wrenches@lists.re-wrenches.org >> >> Change listserver email address & 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 or update participant bios: >> www.members.re-wrenches.org >> >> _______________________________________________ >> List sponsored by Redwood Alliance >> >> List Address: RE-wrenches@lists.re-wrenches.org >> >> Change listserver email address & 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 or update participant bios: >> www.members.re-wrenches.org >> >> > > _______________________________________________ > List sponsored by Redwood Alliance > > List Address: RE-wrenches@lists.re-wrenches.org > > Change listserver email address & > 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 or update participant bios:www.members.re-wrenches.org > > > -- > ~~~~~~~~~~~ > Jeff Clearwater > Village Power Design > linkedin <https://www.linkedin.com/in/jeff-clearwater-0622a312/> > www.villagepowerdesign.com > cell - 413-559-9763 > ~~~~~~~~~~~~~~~~~~~~~~~ > _______________________________________________ > List sponsored by Redwood Alliance > > List Address: RE-wrenches@lists.re-wrenches.org > > Change listserver email address & 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 or update participant bios: > www.members.re-wrenches.org > >
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