I'm trying to charge a power bank of 5V, 5000mAh, using a solar panel 6V, 14W.

I have made the connection from the solar panel to a DC-DC convertor (specification: 3-37V, 3A) which steps down to a fixed voltage of 5V. From there, I fed the output of the DC-DC converter to the power bank input, which requires an input voltage of 5V.

But I can't see any charging indication and charging is not taking place. I'm not able to find why it isn't able to charge the power bank. What is my mistake?

PCB of power bank

  • 1
    \$\begingroup\$ I guess I'd take the 'divide and conquer' approach. For instance, does your power bank work when plugged into a standard USB port or power plug? Are you trying to charge and power a device at the same time (probably won't give good results)? What does the output of your DC-DC convertor look like (voltage, etc.) when powered by a 6V supply? Are you getting 6V out of your panel (solar panels can vary quite a bit from their labeled rating, depending on shade, sun intensity, etc). \$\endgroup\$ – BobT Jun 30 '18 at 17:58
  • \$\begingroup\$ Yes the power bank,work when connected to a standard USB port, \$\endgroup\$ – Shiv Jun 30 '18 at 18:13
  • \$\begingroup\$ No im not charging and drawing the power from the power bank at the same time. The outfit of the Dc-Dc convertor i have set it at files 5V. Yes the solar panel is adequately having enough voltage innfact its Voc is greater than 5V. \$\endgroup\$ – Shiv Jun 30 '18 at 18:17
  • \$\begingroup\$ @Shiv - There sees to be a logical error / contradiction in your question, which makes it difficult to understand your story. You said: "I can't see any Charging indication and charging is taking place". That seems to be saying "I can't see any Charging indication" - so the charger indicates charging is not happening, but "charging is taking place" so somehow (you don't explain how) you know that charging is happening. Perhaps you meant "I can't see any Charging indication and charging is not taking place"? \$\endgroup\$ – SamGibson Jun 30 '18 at 18:21
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    \$\begingroup\$ Then you need to provide more details as others pointed out, because what you have said already is awfully confusing and contradictory. \$\endgroup\$ – Maple Jun 30 '18 at 19:49

It is unlikely a 6V, 14W solar panel has sufficient power to charge your power bank.

14 W is a maximum under ideal conditions and very likely an exaggeration by the vendor. A solar panel will have an IV curve. 6V is a nominal voltage and actual Voc will vary widely depending on irradiance and load.

You need to use a shunt resistor to also measure the solar panel's current while measuring the output voltage.

You do not say how you know whether the battery pack is being charged or not.

With your solar panel, if it has sufficient power to charge at all, it may take days of bright sunshine to charge the battery pack. Do not assume the solar panel is providing 14 watts of power, measure it.

A solar source is typically connected to an MPPT rather than a DC-DC converter.

A solar panel is used for practical purposes only where there is no utility power available. It takes many (e.g. 20) years of use to recoup the cost in electricity savings if ever. The cost analysis is not simply electricity cost ÷ (panel watts x time). Usually the cost of the batteries that need to be replaced every few years prohibits any cost savings.


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