William,
      I have often installed an iota DLS charger on systems with Fortress
batteries to jump start the battery if it shuts down due to low voltage
when the generator has failed. A small generator such as a Honda 2000 can
get the system running.  We even managed to keep an off grid rental ski
house with 8 people there for a Holiday weekend running
With a Honda 2000 regularly refueled by the renter.  The system is an 8000
watt Radian and 1 eVault, 5Kw of solar and 12 Kw generator which had failed
brushes. If the battery shuts itself off due to low voltage solar becomes
worthless as well.

John Blittersdorf




On Wed, May 8, 2024 at 1:17 AM William Miller via RE-wrenches <
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
>
> CA Lic. 773985
>
>
>
>
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