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photovoltaicmidget asked

SmartSolar 100/30 W, V & A constantly fluctuating


I have a SmartSolar 100/30 connected up to a 200W Renogy Panel and a partially charged 200Ah Lithium battery. Using the Victron App the W, V and A of the PV and the battery fluctuate constantly (images for 5mins, but it did same for half hour).
I'm presuming that this is not the behaviour you'd expect to see on the app and it indicates some sort of wiring or connection issue in the system ?
Any hints on a diagnostic procedure and tools for the panel, cabling, connections etc would be appreciated.
NOTE: it was a typical Cloudy/Rainy day in the UK so not much power from the panel.

solar-w.jpgsolar-v-and-a.jpgbattery-v-and-a.jpg


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3 Answers
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markus answered ·

Hi. Maybe your Lithium battery has an internal BMS disconnecting the battery for some safety reason.

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photovoltaicmidget avatar image photovoltaicmidget commented ·

Yes, I have been wondering about the BMS for a while. Will need to get some information on how exactly its designed to behave.

b-m-s.png

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photovoltaicmidget answered ·

Issues with the above turned out to be:
Answer: Loose connection

A 2nd issue then appeared in full sun, which saw very similar behaviour of the graphs fluctuating when the controller was outputting > 15A, with the W cycling from 0 to maximum and back to 0
Answer: The cables inside the battery were underspec'd.
Limiting the "max charge current" to 15A solved the issue. A revised version of the unit can now accept a "max charge current" of 30A.

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Will Tan avatar image
Will Tan answered ·

Discovered my problem of fluctuating charge current was due to a bad circuit breaker. This is a Shortstop heat activated breaker and one of the pins was hot. I bypassed it temporarily and the current fluctuation disappeared! image.jpg


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