[RE-wrenches] Best Battery

Jeff Clearwater jeffc at villagepowerdesign.com
Tue Aug 11 14:30:00 EDT 2020


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 <http://www.villagelab.net>
www.villagepowerdesign.com <http://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.peltz at gmail.com 
> <mailto:jay.peltz at 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
>>     <william at millersolar.com <mailto:william at 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-bounces at lists.re-wrenches.org
>>     <mailto:re-wrenches-bounces at 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.chamberlin at redwoodalliance.org
>>     <mailto:drake.chamberlin at redwoodalliance.org>> wrote:
>>
>>         Hello Wrenches,
>>
>>         What is the best Li-Ion battery to use with an off grid system?
>>
>>         Thanks,
>>
>>         Drake
>>         Athens Electric
>>
>>         -- 
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-- 
~~~~~~~~~~~
Jeff Clearwater
Village Power Design
linkedin <https://www.linkedin.com/in/jeff-clearwater-0622a312/>
www.villagepowerdesign.com <http://www.villagepowerdesign.com>
cell - 413-559-9763
~~~~~~~~~~~~~~~~~~~~~~~
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