<html><head><meta http-equiv="Content-Type" content="text/html; charset=utf-8"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;" class="">Mark,<div class=""><br class=""></div><div class="">It is conceivable to use Li-ion without protection. To do so you must ALWAYS guarantee that you will not over charge, over current, over discharge or charge frozen cells\u2026ever. This is a 0 tolerance rule. In a RE system, how can you be 100% sure? <br class=""><div class=""><br class=""></div><div class="">Modest rates is not the issue. It\u2019s already difficult to overcurrent the GBS cells. Over voltage a cell just once and you can cause damage or possibly fire. Similarly, if you over discharge a cell just once you can damage it and may cause a future fire while charging it normally.</div><div class=""><br class=""></div><div class="">Cell balancers only reduce a small amount of current on a single cell that is becoming saturated. It won\u2019t stop over voltage.</div><div class=""><br class=""></div><div class="">To my knowledge there is no safe way to have a Li battery system without BMS/EMS unless you are always in control of charge/discharge events. </div><div class=""><br class=""></div><div class="">Scold\u2026now that you know, yes, consider yourself scolded.<br class=""><div class=""><div style="color: rgb(0, 0, 0); font-family: Helvetica; font-size: 14px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px; word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class=""><div style="color: rgb(0, 0, 0); letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px; word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class=""><div style="color: rgb(0, 0, 0); letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px; word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class=""><br style="orphans: 2; widows: 2;" class=""><span style="orphans: 2; widows: 2;" class="">Larry Crutcher</span><br style="orphans: 2; widows: 2;" class=""><span style="orphans: 2; widows: 2;" class="">Starlight Solar Power Systems</span><br style="orphans: 2; widows: 2;" class=""><br class=""></div></div></div><br class="Apple-interchange-newline">
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<div><br class=""><div class="">On May 26, 2020, at 12:24 PM, Mark Frye <<a href="mailto:markf@berkeleysolar.com" class="">markf@berkeleysolar.com</a>> wrote:</div><br class="Apple-interchange-newline"><div class="">
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<div class=""><p class="">Thanks Larry,</p><p class="">I am familiar with GBS cells. Would you scold me too badly if I
told you my thought that with modest discharge rates and on the
charge side, with cell balancers installed, and limiting the
charge current to 15A, one doesn't really need the BMS for the
60AH pack? <br class="">
</p>
<div class="moz-cite-prefix">On 5/26/2020 10:47 AM,
<a class="moz-txt-link-abbreviated" href="mailto:larry@starlightsolar.com">larry@starlightsolar.com</a> wrote:<br class="">
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Hi Mark,
<div class=""><br class="">
</div>
<div class="">One of the many benefits of Li-ion is the ability to
provide much higher continuous current than any comparable size
LA battery. </div>
<div class=""><br class="">
</div>
<div class="">You don\u2019t need more than 2kWh (40Ah) and want to
know the smallest battery you can use. To directly answer your
question: A 60AH Elite Power Solutions (GBS cells) battery bank
@ 48V has about 3 kWh of energy storage. This is a tiny battery
bank, just 20\u201dL x 11\u201dW and weighs only 80 pounds. However, it
can provide a whopping 9kW (3C) continuous output and up to 31kW
momentarily! Thats much more than you will likely ever use. </div>
<div class=""><br class="">
</div>
<div class="">Though hard to imagine, this will work with your
inverter. We have built several 3kW inverter systems @ 12V with
a single 100AH battery for starting heavy loads like air
compressors and air conditioners. No problem. Whether this is
the \u201cbest practice\u201d will require more discussion. Let me know if
you need more detailed help as we have many years experience
with Li-ion battery systems.</div>
<div class=""><br class="">
</div>
<div class="">Larry Crutcher</div>
<div class="">Starlight Solar Power Systems</div>
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<div class="">From: Mark Frye <<a href="mailto:markf@berkeleysolar.com" class="" moz-do-not-send="true">markf@berkeleysolar.com</a>><br class="">
Subject: [RE-wrenches] How much Li battery?<br class="">
<br class="">
In the way back machine I remember being at a product roll
out meeting <br class="">
for the brand new Outback FX inverter. I asked the
engineer, what was <br class="">
the smallest battery bank that could be connected to the
inverter. He <br class="">
said on the fly that probably you would want the battery
to "weight" at <br class="">
least as much as the inverter. I thought that was a great
answer.<br class="">
<br class="">
Fast forward, with a 4000w Outback Radian, AC coupled with
2000w of PV, <br class="">
what is the smallest Li battery I would want for stable
operation?<br class="">
<br class="">
My loads don't really need more than 40ah of capacity.<br class="">
<br class="">
What is the latest best practice on this?<br class="">
<br class="">
Thanks.</div>
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