[RE-wrenches] Sunny Island Failure and various related issues

[Mac Lewis]

Hi William,

One other thing.  Remember to specify the 50mV shunt.  "225.01
BatCurSnsTyp".  I believe that means it will drop 50 mV across the shunt
with 500A current throughput.  It's this proportion that determines the
value for 225.03 BatCurGain.  In your case, that should be 50, but I think
it defaults to that if you select a 50 mV shunt.

On Thu, Feb 12, 2015 at 10:11 AM, Mac Lewis <maclewis1 at gmail.com> wrote:

> Hi William,
>
> Yes the Outback shunt should be fine for this application.  See page 72
> here for the calibration:
> http://files.sma.de/dl/15216/SI4548-6048-US-BE-en-20.pdf
> As far as verifying with your clamp meter, I'd say if you can verify
> within 15% (remember to check polarity) then it is properly calibrated.  It
> should do a better job than your clamp meter, but that will help make sure
> you are close.  Check parameter 120.06 TotBatCur to see what the Sunny
> Island thinks the battery current is (in older versions of firmware it may
> be elsewhere).  I have found that with my fluke DC clamp meter (don't know
> the model off the top of my head), I am easily within 5% when the current
> is around 20ADC.
>
> Good Luck
>
> On Thu, Feb 12, 2015 at 8:58 AM, William Miller <william at millersolar.com>
> wrote:
>
>> Mac:
>>
>> Thanks for the advice. We will install the shunt today. A few more
>> questions:
>>
>> 1.  Will the Outback 50ma shunt be compatible. My research indicates the
>> value is correct.
>>
>> 2.  DC clamps are notoriously inaccurate, particularly at low amperages.
>> Will this be a problem, or is shorting the leads adequate?
>>
>> Thanks again.
>>
>> William Miller
>>
>> PS:  We looked at the Midnite cabinets but they put the OPCD too far from
>> the batteries.
>>
>> William
>>
>>
>>
>> On Feb 12, 2015, at 4:45 AM, Mac Lewis <maclewis1 at gmail.com> wrote:
>>
>> Hi William,
>>
>> I want to talk directly to your problem at hand.  I think installing the
>> shunt and properly calibrating it, will fix this system .  In a DC coupled
>> system with a Sunny Island, it is imperative that you use a shunt, unless
>> you are using the Midnite charge controllers with the communications to
>> accurately report all charging (or the non-UL listed SMA charge
>> controllers).  There are so many functions and calculations that the Sunny
>> Island performs that needs accurate SOC calculations.  All of the shutdowns
>> that you are seeing are resulting from faulty SOC measurements.  I wouldn't
>> believe the reported state of health either, because it is using the faulty
>> SOC measurements.  Don't believe state of health until you have a couple of
>> months of operation with the shunt.
>>
>> *Right now, with the system as is, it isn't accounting for the charge
>> coming from the charge controller(s)*.  It is shutting down because its
>> only accounting for AC power processed through the Sunny Island.  I once
>> had a Sunny Island system with an improperly calibrated shunt and it acted
>> just as you describe, strange shutdowns, bad SOC output etc.  After I got
>> it calibrated, it has worked flawlessly.
>>
>> Take your time when you are calibrating the shunt.  Follow the (odd)
>> directions perfectly and it should work.  Verify Sunny Island readings
>> match your DC clamp meter and you should be good.
>>
>>
>>
>>
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>
>
> --
>
>
>
> Mac Lewis
>
> *"Yo solo sé que no sé nada." -Sócrates*
>



-- 



Mac Lewis

*"Yo solo sé que no sé nada." -Sócrates*
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