How to design a solar power based power supply for charging a Li-ion Battery of 3.7v 3500mAh, using TP4056 ?

Specs about Tp4056 based charger using are it is programed for 1.2A current max, and 4.2v constant voltage charging,

A 6v 14watt solar panel to 4056 based charger to charge the Li-ion battey could be feeded?

Will it damage the 4056 based charger?

As the max current produced can reach above 2A.

Our Intention is to provide maximum current available to charge the battery enough and rapidly.

How does the Open circuit voltage of the solar panel affects the 4056 charger? whose operating voltage is 5v to 6v.


The maximum input voltage is 8 V (acc. to p. 2 of the datasheet), so the open circuit voltage of your solar panel has to be lower.

The current will be limited by the charger. The maximum current you could achieve is 1 A (for \$R_\mathrm{prog} = 1.2k\$).

As far as I can see, there won't be any problem with connecting the solar panel to the charger as you don't exceed its limits.

But i see another problem in your use case. If the output power of the solar panel is dropping due to lower solar radiation (e.g., clouds), the charger's input voltage may drop rapidly if it tries to draw too much current. It has an under voltage lockout which should terminate the charging process in this case. As soon as the charging process is terminated, the input voltage of the charger will rise again as the current is around 0 A (open circuit voltage of the solar panel). This means the charger will start charging again, which leads to an oscillation of charging/not charging.

  • \$\begingroup\$ The open circuit voltage of the solar panel is 10-11 volts, will this damage the charge controller? How to reduce the open circuit voltage? \$\endgroup\$ – Shiv Jun 2 '18 at 16:41

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