MPPT 100|20 battery not charging

DIY
,
1

Hi,

I have a SmartSolar MTTP 100|20 connected to:

  • BIG EFB C100 12V 110Ah battery
  • DAH Solar 500W solar panel

Using the Victron app I set the “Battery preset” to “AGM spiral cell” but the battery is not charging.

The Solar section is showing:

  • 1-2W (sometimes)
  • oscillating 13-30V
  • 0.0 A

The Battery section is showing:

  • 11.9V
  • 0.0-0.1A
  • State: Bulk

Any suggestions?

Thanks

2

Have you test PV with mutimeter? VoC + Isc

3

I am sorry, but I do not have a multimeter.

I will try to get one soon.

Is there something I can test?

The voltage from the app is not reliable?

4

Here is the procedure for testing a photovoltaic (PV) panel with a multimeter:

  1. Clean the Solar Panel
    Ensure the panel surface is clean and free of dust or debris so that sunlight can reach the cells effectively37.
  2. Check the Panel’s Specifications
    Look at the label on the back of the panel to note the open-circuit voltage (Voc) and the short-circuit current (Isc)35.
  3. Place the Panel in Direct Sunlight
    Position the panel so it is fully exposed to direct sunlight, with no shade and oriented toward the sun for best results57.
  4. Prepare the Multimeter
  • Set the multimeter to DC voltage mode (symbol: V with a straight and dashed line).
  • For current measurement, switch to DC current mode (symbol: A with a straight and dashed line), but only after ensuring your multimeter can handle the expected current (usually 10A is safe for most panels)36.
  1. Connect the Multimeter
  • Voltage Measurement:
    • Attach the red probe to the positive terminal of the panel.
    • Attach the black probe to the negative terminal of the panel.
    • Read the voltage on the multimeter. It should be close to the Voc value on the panel’s label135.
  • Current Measurement (Optional):
    • Switch the multimeter to DC current mode.
    • Set the range to a value higher than the expected current (e.g., 10A).
    • Connect the probes directly to the panel’s positive and negative terminals.
    • Read the current on the multimeter. It should be close to the Isc value on the panel’s label46.
  1. Compare the Readings
    Compare the measured voltage and current with the values indicated on the panel’s label. The readings should be within 10% of the rated values for proper functioning15.

Note: Always follow safety precautions when working with electrical equipment. Never short-circuit the panel for extended periods, and use appropriate multimeter settings to avoid damage6.

  1. How to Test Solar Panels for Common Problems | Fluke
  2. https://www.youtube.com/shorts/oV8SnZJextc
  3. How to Properly Test Your Solar Panel Output - Airis Energy
  4. https://www.youtube.com/watch?v=GVjkcJD_krc
  5. Comprehensive Guide on Testing Solar Panels with Multimeter
  6. Comment tester un panneau solaire avec un multimètre​ ? | EcoFlow DE
  7. How to Test Solar Panels: Output, Amps & Watts - Footprint Hero
  8. Comment tester un panneau solaire avec un multimètre​ ? | EcoFlow JP
  9. https://www.oscaro-power.com/blogs/lactu-du-solaire/comment-tester-un-panneau-solaire-avec-un-multimetre?srsltid=AfmBOoqKowC6k6E5Rs4IISX2eMl8qWfxHN_C6ntHftvqYFn4Koofh2AT
5

You probable have a poor high resistance connection between the solar panels and the mppt or a panel with a bad joint in.

The mppt is off, there is no current flow, the mppt sees 30V from the panel so it turns on, current starts to flow so the bad connection causes voltage drop so the mppt sees 12V and stops charging. The cycle repeats.

The solar panel voltage has to be 5V higher than the battery to start charging and if it falls less than 1V (or 0.5V) above the battery it stops charging.

6

Thanks for your suggestions.

I will try and see what happens