Hi William, Since the SOC isn’t being reliable maybe due to not charging correctly?
I would recommend going to volts for the relay driver. Thats why I suggested the tristar with RD-1. Because really volts at full is the most accurate. Not knowing how many PV inputs you could do a cascade. jay > On May 8, 2024, at 9:00 AM, William Miller <will...@millersolar.com> wrote: > > Jay: > > Thank you for taking the time. > > We are doing just what you suggest as an interim solution. > > The shortcoming of this work-around is that the highest setting for this > relay function is 90% SOC. This may not be high enough to recalibrate the BMS > units. And again, relying on SOC to drive operational decisions becomes > problematic when one can’t rely on the accuracy of the SOC value. > > > William Miller > Miller Solar.com > 805-438-5600 > www.millersolar.com <http://www.millersolar.com/> > > > On Wed, May 8, 2024 at 7:16 AM jay <jay.pe...@gmail.com > <mailto:jay.pe...@gmail.com>> wrote: > A possible fix. > > You could run a DC relay on the SB PV input that would be voltage triggered > to prevent the battery volts from getting higher than you want. > > The SI has 2 aux relays I think? Or could do a tristar with RD-1 relay that > has 4 channels. > > Just a thought > > jay > >> On May 7, 2024, at 11:11 PM, William Miller via RE-wrenches >> <re-wrenches@lists.re-wrenches.org >> <mailto:re-wrenches@lists.re-wrenches.org>> wrote: >> >> Friends: >> >> I am still wrestling with problems integrating a Sunny Island / Sunny Boy AC >> coupled system to a set of 5 E-vault Max battery cabinets. >> >> As a refresher, with closed loop comms, the Frequency Shift Power Control >> system is not working, or not working quickly enough, and when nearing full >> charge, the voltage can spike up to 66 volts and the SI system shuts down. >> Fortress has told me in a roundabout way that they agree this is a real >> problem and they are working on a solution. >> >> Another problem has reared its head: If the E-Vaults do not get charged >> fully every 5 to 7 days, the BMS units SOC value becomes radically out of >> calibration. The E-vault will report a higher SOC than is realistic. The >> SI system starts the generator based on SOC and if the SOC is reported as >> high the generator don’t start. Sooner rather than later the battery >> voltage gets too low and the system shuts down. >> >> I have been tweaking on the settings like days-since-full-charge to attempt >> to get this cycle to stop. No definitive answer yet. >> >> Here is the reason I am writing: Yesterday I could not get the Sunny >> Islands to start. The battery voltage was 46 which should have been enough >> but for some reason they just would not start. Because of this I could not >> charge the batteries from generator or from AC coupled solar. I called SMA >> but they told me they could not advise because of the non-compatible >> batteries. I asked about the emergency charging procedure in the manual but >> I was told this does not work with lithium batteries. The process is pretty >> scary anyway so I was not inclined to try. >> >> SMA told me I may need an external 48 volt charging system. I have heard of >> this being required in certain scenarios by wrenches. This would be a huge >> pain in the ass: ordering one, waiting for it, hooking it up, etc. >> >> Here is what I did: I initiated the Quick Start Configuration mode and told >> the SI system there was a new battery bank. I told it the bank was a very >> small VRLA battery. The SI system accepted the 46 volts, started up and >> allowed a generator charge. After an hour or so we reprogrammed the system >> for lithium and problem resolved, at least for now. >> >> Hopefully this trick may help one of you some day. If it does, it was worth >> my time typing it out. >> >> William >> >> Miller Solar >> 17395 Oak Road, Atascadero, CA 93422 >> 805-438-5600 >> www.millersolar.com <http://www.millersolar.com/> >> CA Lic. 773985 >> >> >> _______________________________________________ >> List sponsored by Redwood Alliance >> >> Pay optional member dues here: http://re-wrenches.org >> <http://re-wrenches.org/> >> >> List Address: RE-wrenches@lists.re-wrenches.org >> <mailto:RE-wrenches@lists.re-wrenches.org> >> >> Change listserver email address & settings: >> http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org >> <http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org> >> >> There are two list archives for searching. When one doesn't work, try the >> other: >> https://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/ >> <https://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/> >> http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org >> <http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org> >> >> List rules & etiquette: >> http://www.re-wrenches.org/etiquette.htm >> <http://www.re-wrenches.org/etiquette.htm> >> >> Check out or update participant bios: >> http://www.members.re-wrenches.org <http://www.members.re-wrenches.org/>
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