Can my Classics be responsible for this? Help!

[Trukinbear]

Hi guys, me again.
We've been dealing with this Sunny Island system as you can probably remember, and SMA has swapped out my Sunny Island - well they sent it and I swapped it out - with almost all the bugs worked out the tech noticed something weird, and so did I. It seems my system will be snoozing right along at night with a light 8-12A load on my end, no generator, grid, or solar active, all of a sudden my Sunny Island will log battery current IN anywhere from 400A to almost 4000A. The tech at SMA suggests it is a communications error with the Classics, MODBUS/Canbus, and the Sunny Island - but for the first time in forever they all seem to be working just as they should, the Sunny Island sees the two Classic 250V's as SIC-40's, just as designed. But then the tech never heard of 'i-loop' which I initiated to solve the chronic W309 problem, so there is that. The other unit never logged anything odd like this, the replacement from SMA actually looks to be a used unit that might have been dropped and glued back together with RTV. I think it is the Sunny Island, please tell me my Classics can't do this. Nowhere in any of my mymidnite2 data do I ever see any impossibly weird numbers.

[boB]

Very strange...

Where does the SMA say that current is coming from ?

[Trukinbear]

They say it doesn't exist.

[boB]

Where are you getting the information exactly ?

[Trukinbear]

From the logs on the memory card that resides in the slot on the Sunny Island. The attached chart was done by SMA support from data from the card.

[Trukinbear]

On the chart - the top line is what is actually happening, all the lines down to ~400 and around ~3500A are of course the aberrant readings.

[Trukinbear]

IF it was a communications issue with the Classics just unplugging the data cable would remove that from the system while still allowing my Classics to count my Ah in the night. Right? I'm going to try to prove or disprove this as numbers that big are scaring the whee out of me... well obviously I'm not putting 175,000 watts to my battery all of a sudden.

[boB]

I don't think it is because of a communications error because error detection would (or should) keep that from happening. Even if you plug in and plug out comms while it is communicating.

[FNG]

I dont see this being likely, The registers that hold output current on the classic are not large enough to hold those size values.

[Trukinbear]

Thank you, I'll pass that along.

[Trukinbear]

I pulled the comm cable from the Classic to the MODBUS/Canbus adaptor at 6:22PM on 11/09 and sent in the data from my memory card the next morning to SMA. Here is their reply:

• Hello Michael,
  The current spikes stopped when the Midnite unit was disconnected. The last spike was recorded at 6:22 PM on 11/9. Based on the data, I see the Midnite device seems to stop communicating at 6:45 PM. See attached battery current graph. In my mind, this confirms that the issue has to do with the communication between the SI and Midnite.

[FNG]

Not sure what to say there. I guess a bad cable could be corrupting packets? I cant see the classics being responsible as they dont hold values that large

[Trukinbear]

The blue cables I bought from you guys that run from the Classics to the MODBUS/Canbus are standard cables of some sort? I've got lots of Cat5E-600 cables and ends leftover from installing the RSS...

[FNG]

They are a standard 4 conductor phone cable.

[Trukinbear]

Thank you!