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hosinfefer asked

Help with 100/50 MPPT

I have a pretty basic setup. 2 panels running thru a 100/50 MPPT to a battery and inverter. I also have a automatic trasfer switch that kicks my load to street power (13.0V) and brings the load back to battery (13.8v). The mppt goes bulk charge until 14.0V then holds absorption and drops off to 13.5v for float. This system has been working perfect happily bouncing between battery and street power when things are not sunny for a few days.


I now notice however, the charge controller tells me its at 14.0V but the inverter and transfer switch never see above 13.3V which causing the load to also be on street power. I even took a multimeter to read the battery voltage when the battery just flipped into 14.0v absoption and sure enough the battery was only 13.3V. Why is the controller reading voltage incorrectly and now not charging fully? Any idea's?

MPPT Controllers
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2 Answers
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svtti123 answered ·

Hi Hosinfefer,

I would check the voltage at the controller terminals if its at the controller display voltage 14v then would expect you have a bad connection in the wiring between control and battery.

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hosinfefer answered ·

so I have double checked all the cables\lugs and everything seems good and tight. The other thing to note is now the sun is down and had been for 4+ hours and all equipment is reading the same 13.16 V. Battery, charge controller, inverter and transfer switch. Its only when the charge controller is charging does its voltage go out of sync. I will check tomorrow when its gets sunny but I suspect 3 items will be in sync with the charge controller being out of sync.

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