MPPT output reading 2.9V

herbnhoneyvan · December 2020

Hi, I have 2 250 watt panels connected in parallel producing an average of 35 V. I've hooked them up to a 40 amp Epever MPPT and it says the output voltage is 2.9V. It says that my batteries aren't charged enough but they're LiFePO4 batteries and my multimeter test of the batteries (2 100 Amp connected in parallel) says 13.1V.

Any advice is welcome. I'm not sure what is going wrong. I've double checked the connections and they're all good.

BB. · December 2020

Use your multimeter to measure the voltage at the Epever terminals (solar array and battery terminals) directly and see what you read. Also, retorque the electrical connections too.

It is possible to "confuse" (or even damage) a solar charge controller if you connect the power in the "wrong order"... Always connect the battery bank first, and disconnect last.

If you have the solar array connected first (or without) the battery bank connected first--The charge controller can boot to the wrong battery voltage (i.e., 24 volt vs 12 volt auto configure) or even be damaged.

Did the system ever work and then fail? Or is this a new install?

For the array wring, you can connect a 20-100 Watt 120 VAC filament lamp (normal house bulb) to the array and then measure the array voltage (under full sun). The light bulb provides some loading to the array to make sure there is a "solid electrical connection" from the array to the controller (a standard voltmeter takes almost zero current--And you can have a loose/corroded electrical connection that will read good voltage but is a high resistance connection--And will a load will read near zero ).

That is where I would start...

-Bill

BB. · December 2020

Herb,

I would also ask that you keep your debugging questions in this one thread... Then we can see the previous history and things you have tried (such as you did try rebooting the controller from the battery bank in a previous discussion).

-Bill

MPPT output reading 2.9V

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