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amajor avatar image

LiFePo4 battery voltage variation

Hello,

I have a MPPT SmartSolar 100/50 with a LiFePo4 200ah 12V battery Voltage is constant when sun is covered and there is less sun, but voltage seems to vary more when sun is at its best and MPPT is in absorption mode with voltage sometimes hitting 13V which can turn of my skylight roof vent/ 12V fan at times. Would you know where the issue can come from? I have the base LiFePo4 battery preset configured on my MPPT regulator
Many thanks for your help

Adrien

MPPT - Solar Charge ControllerLithium Batterymppt smart solar
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2 Answers
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RickP answered ·

Fully charged, a LiFeP04 12 volt battery bank should read a touch over 13 volts (13.2 to 13.8, depending on the manufacturer). In absorption mode my battery maker suggests a setting of 14.2 to 14.6 volts, and the BMS will stop anything 14.7 or higher. In other words, I think your SCC is working fine, and is properly charging your bank.

If you have loads that are very sensitive to voltage over 12 volts, you may have to place a limiting device between the battery and load. As an aside, most 12 volt equipment is actually designed to run on voltage higher than 12 volts, as it takes more than 12 volts to charge a battery... your fan shouldn’t be cutting off at 13 volts. In my 24 volt system (12v batteries in series/parallel), I have an Orion 24/12-70 converter that can be set to the output voltage I need. It, for example, is set to 13.3 and everything works perfectly.

I think you’re fine, but might need to see why that fan is cutting out.

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amajor avatar image
amajor answered ·

Hello Rick,

Thanks a tons! I have further analyzed the fans behavior and it seems to turn off when the sun is hitting the roof of the van and voltage actually exceeds 14.6 V (it hits between 14.8-15V generally, then turns off)

Any views on this behavior? I guess the fan has perhaps a problem but I want to make sure that no other stones are left unturned before replacing it !

Important to note that this behavior only happens with the fan but could such voltage increase come from bad wiring, cable size, etc?

Thanks again for the help


best rgds

Adrien

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Your smartsolar actually records battery minimum/maximum voltages.

Look at your history..