Epever Tracer8420AN MPPT Solar Charge Controller Strange behavior

[doschhar]

I have 4x 195 Watt 12 Volt Monocrystalline PV (780W total) connected to a Epever Tracer8420AN that feeds into 4x Lifeline GPL 31-T 12V 105AH (2 years old) parallel 12V battery bank on my Beneteau sailing yacht.
Everything works fine until the charging current exceeds about 20 amps. Then the display of the controller first shows almost no battery voltage and therefore detects over discharge (?!) and then goes up to about 14.5V even so the battery bank meter of the boat itself shows around 12 V at all times and stops charging until I reset the charger just to get the same problem again after about 5 minutes.

No load is connected to the Epever.
The solar panels show 22.2V all the time at the display.
Strange thing is that I can charge the battery bank via a 220V shorepower Cristec charger with 40 amps - no problems.

What could cause this strange behavior?

Thanks for reading.
Harald

[noelex 77]

Harald, I have never used that particular controller, but as no one else has chimed in I will add my 2c worth.

Most of these types of problems are due to high resistance in one of the connections. Check the voltage drop over both the positive and negative cables, measuring from the solar panels to the input on the controller and then from the output of the controller to the battery bank. This needs to be done while the solar panels are producing significant power. A quick and crude, but often effective technique for high current devices is to feel the temperature at each of the connections. It will be warm if there is significant resistance.

While the above is certainly worth checking, your symptoms are not typical of this type of fault. I suspect your controller is simply defective. Unfortunately, MPPT controllers are not the most reliable of electronic devices, and the failure rate is reasonably high. It is possible your unit is simply overheating when the solar panels are putting out a higher current. Solar controllers need plenty of ventilation. As a test try mounting a temporary fan blowing over the controller and see if that fixes the problem. This will also show if the internal fan (if one is fitted to this controller) has stopped functioning.

If not, you can test if the solar controller is defective by simply bypassing the connections and wiring the panels directly to the batteries. As you have low voltage "12 v" solar panels the output should be close to same output achieved when the controller was working normally. If you do decide to do this you need to keep a careful eye on the battery voltage. If you let this climb significantly above the normal absorption voltage, your batteries and even other electronics could be permanently damaged.

Finally, you can disconnect and test the solar panels individually looking at the maximum voltage and then the maximum current each panel can produce.

These tests should narrow down the defective component.

[doschhar]

I will check the wiring and connection to and from the controller today.

[doschhar]

Found the problem.
80 amps mechanical fuse from mppt controller to battery bank was malfunctioning.

Thanks for the help noelex_77*