I'm trying to design a parallel charger for 4 18650 batteries using 4 TP4056. The main idea is to isolate each battery when the "External Power" is connected, so each charging circuit can charge its battery and the load can remain powered. Then, when the "External Power" is removed, the TP4056s are disconnected via an N-channel Mosfets and all the batteries are connected in parallel via P-channel Mosfets. If I'm able to make it work, the next stage will be to try connect the "Battery pack" to a BQ27441.

In the schematic, I'm including protection for each battery, and I use the suggestion of this for preventing reverse polarity.

This is the first time I'm trying to make something like this, so I'm not sure if my approach is the correct one. Do you guys have any suggestion/comment?

Here I attach the first attempt, this circuit will be replicated 3 more times, so the final design will have 4 TP4056 + protection + ptcs + N/P-channel Mosfets.

enter image description here

Thanks in advance!

  • \$\begingroup\$ What if one cell is at fault? Leaky or shorted \$\endgroup\$ – Sunnyskyguy EE75 Dec 17 '17 at 8:05
  • \$\begingroup\$ There's generally no need to thye cells in parallel batteries of lithium cells during charging, is only series batteries that need balance charging. \$\endgroup\$ – Jasen Dec 17 '17 at 9:32
  • \$\begingroup\$ Hello @Jasen, the idea of putting the batteries in parallel when the "External Power" is removed is to sum the currents of all the batteries and isolated them during charging so each TP4056 can charge its battery alone. I'm not sure if I explained better. Regards! \$\endgroup\$ – Felipe Navarro Dec 17 '17 at 18:40
  • \$\begingroup\$ I don't know how I managed to post such an unclear comment, I mean why not have the batteries in parallel all the time? if you want to charge faster use a faster charger. \$\endgroup\$ – Jasen Dec 18 '17 at 22:38

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