I have spoken with a li battery researcher. Do not charge over 85% of battery full charge voltage and they will last over 25 years. But go above or below bottom and trouble
On Sun, May 24, 2020, 10:27 AM Jay <jay.pe...@gmail.com> wrote: > One question I have for those more versed than me in lithium is, I’m under > the impression that having a lithium battery in float for years isn’t good > for it. Or at the very least it has to be cycled with some regularity. > > I’d like to hear data on that > > Thx > Jay > > Peltz power. > > > > > > On May 23, 2020, at 10:08 PM, Ray <r...@solarray.com> wrote: > > > > I suggest starting with a very simple look at the continuous output rating > of the battery and match that to the inverter continuous rating. This ends > up with quite a bit more battery than you might think at first. However, > if the customer paid the big bucks for a battery backup system, they should > at least get enough battery to operate the inverter at its rated power. > Anything less, I would consider poor design. The same goes for lead acid > batteries, they just don't work well, even on grid, when the battery is > undersized. Even lead acid batteries have maximum current output ratings > that should at least be matched to the inverter rating. > > If you WERE going to under size the battery, then you should keep it safe > by reducing the size of the inverter battery breaker as well. I know this > "micro battery for GTB" is becoming a trend, but it doesn't mean its right. > > Ray Walters > Remote Solar > 303 505-8760 > > On 5/23/20 5:48 PM, Mick Abraham wrote: > > Greetings, All~ Mark Frye had asked: "...with a 4000w Outback Radian, AC > coupled with 2000w of PV, what is the smallest Li battery I would want for > stable operation?" > > Mick's reply: In the lithium arena, one often finds the ratings in > kilowatt-hours rather than in amp-hours. This is an easy conversion for us > energy nerds to make, so below I'm mainly using watts & watt-hours with > occasional conversions to amp-hours. > > I suggest that you start with the spec sheet (of whichever brand lithium > battery is on your radar), & see what the manufacturer says about > "allowable rate of recharge". You may find that C/2 is an acceptable rate > with several manufacturers, Mark--much faster than what we're accustomed to > with typical lead-acid batteries. Let's assume: > > * ...that your AC coupled PV array crests around 1800 watts to the battery > when there are no loads > * ...that the battery is below 100% state of charge, and > * ...that the solar conditions are optimal. > > Let's further assume that those conditions represent your battery's > highest energy rate in either direction. > > 1800w X two hours = 3,600 watt-hours dividing by 48v nominal = 75 > amp-hours in the above hypothetical situation. > > ++++++++++++++++++++++++++++++ > > The rate at which a battery can receive energy is (usually) also the rate > at which it can comfortably deplete, so let's briefly look at the flip > side: Assuming the battery mfr. wants the watt-hours to be no less than two > times the maximum wattage, a 3600 watt-hour (C/2) battery should not be > depleted faster than 1800 watts. Your 4kW Radian, Mark, could exceed that > if the loads demand it--& maybe your loads don't. Motor starting surges > should probably be part of the thinking & it wouldn't hurt to ask the > mfr.'s opinion about short term surges which briefly deplete the battery > faster than the hypothetical two hour rate. > > By approaching this question based on the battery manufacturer do's & > don'ts, one improves the chance of getting warranty coverage should it > later be needed. "What the large print giveth, the fine print taketh away." > > The Wrench List is the Bomb! > > Mick Abraham, Proprietor > www.abrahamsolar.com > > Landline: 970-731-4675 > Cell phone or for text messaging: 970-946-6584 > ᐧ > > _______________________________________________ > 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://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/maillist.html > > 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://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/maillist.html > > 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://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/maillist.html > > List rules & etiquette: > www.re-wrenches.org/etiquette.htm > > Check out or update participant bios: > www.members.re-wrenches.org > >
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