Yes Richard is right. When doing these one cycle or lifetime comparisons
we should derate the rated or useful KWH figures by the round trip
efficiency:
Round Trip Efficiencies:
FLA - 82-85%
AGM - 88-92%
AGM-Carbon - 90-94%
LFP - 94%-98%
:)
jc
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 <[email protected]
<mailto:[email protected]>> 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
<[email protected] <mailto:[email protected]>> 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:[email protected]
<mailto:[email protected]>] *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
<[email protected]
<mailto:[email protected]>> 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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