I have combined five 18650 cells in parallel and i am charging them using a single tp4056 circuit . The problem i am facing is that the module keeps on charging. I had to stop the charging manually at 4.25 volts.

When i am charging a single cell, the over charge protection kicks in at 4.19 volts, which means that circuit is working properly

My question is that why would it keep overcharging when multiple cells are connected in parallel?

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    \$\begingroup\$ Is the device designed to charge multiple parallel cells? \$\endgroup\$ – Andy aka Jul 19 '18 at 15:12
  • \$\begingroup\$ Charging multiple parallel cells shouldn't be a problem as the voltage remains the same. The charging duration definitely increases as the circuit is charging at <0.1C but i think thats good for battery health. Right? \$\endgroup\$ – Saad Muzaffar Jul 20 '18 at 16:20
  • \$\begingroup\$ A great idea but that just doesn't hold water with (say) LiPo or ion cells unfortunately because the battery monitor is getting confused by the excessive current taken at lower voltages due to parallel cells. \$\endgroup\$ – Andy aka Jul 20 '18 at 16:22
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    \$\begingroup\$ You may be right. I thought of the same thing that controller was getting problematic due to high current so i added a 1ohm resistance between the battery pack and controller to limit the current going back into tp4056. And to my surprise the controller started working properly . But when i further increased the value of resistance the controller stopped charging at even lower voltages . With a 5ohm resistance the controller stopped charging at 4volts. \$\endgroup\$ – Saad Muzaffar Jul 21 '18 at 17:03

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