[RE-wrenches] Integrating Fortress E-vault maxes into an SI AC-coupled system

[William Miller]

Jay:

Good question. I assumed some kind of FET circuit but that is only my
assumption.

However an open relay exhibits some fairly high impedance.

The symptoms indicate the SI shuts down but the batteries remain connected.
Something allows 69 volts on the battery terminals…

William Miller
Miller Solar.com
805-438-5600
www.millersolar.com


On Sun, Nov 12, 2023 at 2:22 PM Jay via RE-wrenches <
re-wrenches at lists.re-wrenches.org> wrote:

> Maybe someone else knows differently but it was explained to me that the
> fortress batteries have a relay that disconnects the battery if the voltage
> gets to high or low. There isn’t any electronic  device to change battery
> impedance besides what the actual cells are doing.
>
> Jay
>
> On Nov 12, 2023, at 12:50 PM, Jerry Shafer via RE-wrenches <
> re-wrenches at lists.re-wrenches.org> wrote:
>
> 
> Regarding the SI Inverters,for me it works best to eliminate the bat temp
> sensor and put in a resister set to be 75 degrees, this will prevent the
> charger over under charge issue.
> Fun times
>
> On Sun, Nov 12, 2023, 12:36 PM William Miller via RE-wrenches <
> re-wrenches at lists.re-wrenches.org> wrote:
>
>> Friends:
>>
>>
>>
>> I am still working on getting the E-vaults to play nice with the Sunny
>> Islands and Sunny Boys.
>>
>>
>>
>> With Open loop I was getting significant discrepancies in the reporting
>> of SOC in the e-vaults versus that reported by the SI inverters.  This
>> discrepancy did not diminish over time.  The discrepancy caused
>> unacceptable charging and generator operations.
>>
>>
>>
>> I got Closed loop hooked up, but I found that every few days the SI
>> inverters would shut down due to a battery over-voltage condition.  I
>> believe that when the e-vaults are near 100% SOC the BMS units increase the
>> battery impedance which means any charging current applied will cause the
>> voltage spike I have been seeing.   I was able to measure these conditions
>> myself on site, although they were very fleeting and required recording
>> with the Fluke87 Min-Max function (love this meter!).
>>
>>
>>
>> I was able to extract log files from the Sunny Island primary inverter
>> and perform some analysis.  It appears when I turned on remote BMS on the
>> SI (as part of the Closed loop protocol) it disabled the Frequency-Shift
>> Power Control.  This means the SI inverters have gone from having poor
>> control over battery charging to having no control over battery charging.
>>
>>
>>
>> I have documented my research here
>> <https://millersolar.com/MillerSolar/case_studies/36_SIFortress/36_SunnyIslandFortressIntegration.html#Inhibit>.
>> There is a table of contents to take you to the latest information.  I
>> appreciate pertinent comments any of you might have.
>>
>>
>>
>> By the way, if anyone has called SMA tech support for help on a Sunny
>> Island system, you have likely been asked to extract log files, zip them up
>> and send them off for review (and waited a long time for a reply).  I am
>> the kind of guy who does not like to wait for solutions and who likes to
>> figure out things for himself.  I have taught myself how to evaluate those
>> log files. I will be posting a web page on the subject.  In the meantime,
>> if you are interested, two of my analysis Excel sheets are linked in the
>> case study.  I will be expanding on this and providing resources to any
>> integrator that wants that knowledge.
>>
>>
>>
>> Thanks in advance for any insight.  I hope I am wrong about this and I am
>> just missing something.  I also hope revealing my headaches will help
>> someone someday…
>>
>>
>>
>> William
>>
>>
>>
>> Miller Solar
>>
>> 17395 Oak Road, Atascadero, CA 93422
>>
>> 805-438-5600
>>
>> www.millersolar.com
>>
>> CA Lic. 773985
>>
>>
>>
>>
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