SmartSolar 100/50 Erratic charging/voltages

I have 2x 425w Longi panels connected in series to a SmartSolar 100/50, when charging my 300ah Kepworth Lifepo4 battery, if the wattage reading in the Victron app goes over approx 500w the battery voltage in the app starts climbing and the jumps up to as high as 17v very briefly then charging stops, the battery voltage in the app then drops to 13.3v, which is lower than when the battery is tested. The voltage is reading around 70v from the panels with the current being around 9a. I have selected the Smart lifepo4 setting in the app, any ideas what could be causing this?

This could be due to a poor contact somewhere in the wiring between the MPPT and the battery causing high resistance and voltage drop. It could he poor crimp, loose terminal, broken wire, poor isolation switch or breaker and can be on +ve or -ve wiring. When charging, get your multimeter out and check voltage at all connection points looking for voltage drop.

Thanks for the reply, after testing i suspect the issue is with the breaker, i will remove and replace today and test again

Are you using one of the cheap resettable breakers like below, if so these are known for poor reliability unless genuine products from quality manufacturer like Blue Sea. Much better to use a fuse. Ebay and Amazon are full of these cheap unreliable breaker.

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Thank you very much for the help, yes I was using one of those cheap resettable breakers, I have swapped out for a fuse and now everything seems good.

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