enter image description here


I want to charge a 2-Cell Li-ion battery (7.4 V) using CN3722 Solar Charge controller and a SMPS power supply (instead of using solar supply). I have designed my circuit to charge with maximum 1A current. The MPPT voltage is set at 17.5V and the battery float volatage is set at 8.4V.

Thus, through SMPS, I am providing 12V, 1.5A power input to the circuit. In this case, the battery float voltage is found to be 8.4V. but, when i connect my battery to charge it, the circuit is consuming at the rate of 2A by lowering by supply voltage to 10V.

When I increase my SMPS supply current to 2.5A with voltage at 12V and connects the battery to charge it, again my circuit is drawing more than 3A by lowering my supply voltage to 9V.

So, What should be the reason of this problem? Is it due to the fact that I am providing a SMPS supply to CN3722 which is a solar charge controller. Is it possible to charge a battery through a solar charge controller by providing SMPS power supply?

  • \$\begingroup\$ Please help me to solve this problem. \$\endgroup\$ – Aakash Dey Dec 17 '18 at 6:18
  • \$\begingroup\$ Anything wrong in this circuit as for the above problem? \$\endgroup\$ – Aakash Dey Jan 29 at 6:03
  • \$\begingroup\$ Sounds like the MPPT isn’t tracking, but have you tried a weak source? \$\endgroup\$ – winny Jan 29 at 6:53
  • \$\begingroup\$ @winny, I am providing 25V,3A SMPS power supply to the charge controlller. However, This problem is now over, don't know how, only I have replaced the inductor. But, now I am facing a new problem. I have mentioned the new problem in my new question. Please help me to solve that new problem. \$\endgroup\$ – Aakash Dey Jan 29 at 9:30
  • \$\begingroup\$ "This problem is now over, don't know how" Major red alert here! This is how you run in to very costly issues down the line! \$\endgroup\$ – winny Jan 29 at 9:55

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Browse other questions tagged or ask your own question.